Filtration device and method for operating the filtration device

Abstract

To provide a filtration device configured so as to prevent a filter sand washing part which is used to wash filter sand from being blocked.SOLUTION: A filtration device is configured to subject raw water to filtration treatment by flowing the raw water upward over a filtration layer 3 formed by filling filter sand thereinto and to eject, as detergent drain, water pumped up together with the filter sand by air for air-lift supplied to the filtration layer 3 by an airlift pump 10, which comprises a filter sand washing part 20 that washes filter sand lifted up by the air for air-lift and cleaning-air blowing-in means 50 that blows cleaning air into the filter sand washing part 20.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an upward flow moving bed filtration apparatus for continuously washing filter sand, and a method for operating said filtration apparatus. [Background technology]

[0002] For example, filtration equipment used in sewage water treatment includes gravity downflow filtration (fixed bed), gravity upflow filtration (fixed bed), and upflow moving bed filtration. Of these, the upflow moving bed filtration method is a method in which the filtering operation is performed while the filter sand, which is the filter medium, is continuously washed, so there is little increase in head loss in the filter basin, filtered water can be obtained continuously, and maintenance is easy, and it is therefore widely used in water treatment.

[0003] As a filtration device of the upward flow moving bed filtration method, there is known a device that filters raw water (water to be treated that contains suspended solids (SS)) by flowing the raw water upward through a filtration layer formed by filling the filtration sand, and that is configured to discharge water that is raised together with the filtration sand by air lift air supplied to the filtration layer by an air lift pump as washing wastewater (see, for example, Patent Document 1). In this filtration device, the filtration sand raised by the air lift air is washed in a filtration sand washing section. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-166113 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the filtration device described in Patent Document 1, foreign matter and impurities (such as biofilms and larvae of aquatic organisms, hereinafter referred to as "foreign matter, etc.") may adhere to and accumulate as dirt in the filtration sand washing section over the course of operation. For this reason, depending on the amount of accumulated foreign matter, etc., this may lead to clogging of the filtration sand washing section, causing problems in the operation of the filtration device.

[0006] The present invention has been made in consideration of the above problems, and has an object to provide a filtration apparatus capable of preventing clogging of a filtration sand washing section used to wash filtration sand, and a method for operating the filtration apparatus. [Means for solving the problem]

[0007] The characteristic configuration of the filtration device according to the present invention for solving the above problems is as follows: A filtration device configured to filter raw water by flowing the raw water upward through a filtration layer formed by filling filtration sand, and to discharge water that is raised together with the filtration sand by air lift air supplied to the filtration layer by an air lift pump as washing wastewater, A filtration sand washing unit that washes the filtration sand lifted by the air for the air lift; A cleaning air blowing means for blowing cleaning air into the filter sand washing section; The purpose of this project is to provide the following:

[0008] According to the filtration device of this configuration, cleaning air is blown by the cleaning air blowing means into the filtration sand washing section, which washes the filtration sand lifted by the air lift air. As a result, even if foreign matter or the like adheres to or accumulates in the filtration sand washing section as the operation time of the filtration device passes, it is peeled off and removed by the cleaning air blown into the filtration sand washing section. Therefore, clogging of the filtration sand washing section can be prevented.

[0009] In the filtration device according to the present invention, The filtration sand washing section includes: A separator for separating the filter sand; a washer into which the filtration sand separated by the separator and filtrate water that has passed through the filtration layer are introduced and the filtration sand and the filtrate water are brought into countercurrent contact with each other to wash the filtration sand; Including, The cleaning air blowing means preferably includes a cleaning air jetting pipe arranged to jet cleaning air toward a filtered water inlet in the washer into which the filtered water is introduced.

[0010] According to the filtration device of this configuration, when cleaning air is jetted from the cleaning air jet pipe toward the filtered water inlet in the washer, the jetted cleaning air is blown from the filtered water inlet into the washer and also blown through the washer into the separator, thereby making it possible to simultaneously clean the washer and the separator, thereby improving cleaning efficiency.

[0011] In the filtration device according to the present invention, A turbidity meter for measuring the turbidity of the cleaning wastewater; a control device that controls the amount of cleaning air blown by the cleaning air blowing means based on the measurement value of the turbidity meter; It is preferable that the device further comprises:

[0012] With the filtration device of this configuration, the amount of cleaning air blown in by the cleaning air blowing means is controlled by the control device based on the measurement value of the turbidity meter which measures the turbidity of the cleaning wastewater, making it possible to blow in the appropriate amount of cleaning air, neither too much nor too little, depending on the degree of dirt.

[0013] Next, the characteristic configuration of the operating method of the filtration device according to the present invention for solving the above problems is as follows: A method for operating a filtration device configured to filter raw water by flowing the raw water upward through a filtration layer formed by filling filtration sand, and to discharge water that is raised together with the filtration sand by air lift air supplied to the filtration layer by an air lift pump as washing wastewater, A filtration sand washing step in which the filtration sand lifted by the air for airlift is washed in a filtration sand washing section; A cleaning air blowing step of blowing cleaning air into the filter sand washing section; The purpose of this study is to encompass the above.

[0014] According to the operating method of the filtration device having this configuration, a filtration sand washing process is performed in which the filtration sand lifted by the air lift air is washed in the filtration sand washing section, and a cleaning air blowing process is performed in which cleaning air is blown into the filtration sand washing section. As a result, foreign matter and the like that has adhered to and accumulated in the filtration sand washing section as the operation time of the filtration device passes is peeled off and removed by the cleaning air blown into the filtration sand washing section. Therefore, clogging of the filtration sand washing section can be prevented. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing a filtering device according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic configuration diagram showing an enlarged view of a main part of a filtration device according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The present invention will be described below with reference to the drawings. However, the present invention is not intended to be limited to the embodiments described below or the configurations shown in the drawings. In addition, in Fig. 1 and Fig. 2, the various devices constituting the filtration device of the present invention are appropriately exaggerated or simplified for ease of explanation, and do not strictly reflect the size relationship and arrangement of the various devices in the actual filtration device.

[0017] <Overall composition> Fig. 1 is a schematic diagram showing a filter device 1 according to one embodiment of the present invention. As shown in Fig. 1, the filter device 1 includes a filter tank 2 having a cylindrical body 2a and an inverted cone-shaped bottom 2b, a filter layer 3 formed by filling the filter tank 2 with filter sand as a filter medium, an air lift pump 10 for raising the filter sand at the bottom of the filter layer 3 together with water, a filter sand washing section 20 for washing the filter sand raised by the air lift pump 10, and a cleaning air blowing means 50 for blowing cleaning air into the filter sand washing section 20.

[0018] At the bottom of the filtration tank 2, a raw water inlet section 4 is provided, through which raw water containing suspended solids (SS) flows into the filtration layer 3 as treated water. A raw water distribution plate 5 is disposed in the raw water inlet section 4, which is composed of a single or multiple distribution plates having a triangular cross section and an open lower side. A raw water inlet pipe 7 is connected to the raw water distribution plate 5 via a guide pipe 6, and raw water is supplied from the raw water inlet pipe 7 to the raw water distribution plate 5 via the guide pipe 6. Thus, the raw water flows out from the bottom of the raw water distribution plate 5 as shown by the arrow A, and while passing through the filtration layer 3 as an upward flow, the SS components contained in the raw water are filtered by the filtration layer 3. The treated water (filtrate) after filtration overflows from the top of the filtration tank 2 and flows into the water collection trough 8 as shown by the arrows B, C, and D in FIG. 1, and is sent to the next treatment device (not shown) through the filtrate discharge pipe 9.

[0019] <Air lift pump> The air lift pump 10 includes an air lift pipe 11 disposed inside the filtration tank 2 so as to extend from the top to the bottom of the filtration tank 2, and a pressure opening and closing type air compressor 12 disposed outside the filtration tank 2. The air compressor 12 serves both as a supply source of compressed air to be used as air lift air and as a supply source of compressed air to be used as cleaning air.

[0020] A box body 13 is attached to the air lift pipe 11 so as to enclose the lower end of the air lift pipe 11. A suction pipe 14 is connected to the bottom of the box body 13 so as to communicate with the inside of the box body 13. The box body 13 and the air compressor 12 are connected by an air supply pipe 15. A flow control valve 16 and a flow meter 17 are interposed in the air supply pipe 15 from the upstream side to the downstream side of the compressed air flow in this order. The flow control valve 16 has its valve opening controlled in response to a valve opening signal from a control device 70 described later. The flow meter 17 measures the flow rate of compressed air flowing downstream of the flow control valve 16 in the air supply pipe 15. The measurement signal of the flow meter 17 is transmitted to the control device 70 described later. The control device 70 reads the measurement signal of the flow meter 17, calculates the valve opening of the flow control valve 16 so as to bring the current flow rate of compressed air closer to a target value, and transmits a valve opening signal based on the calculated valve opening to the flow control valve 16.

[0021] <Filter sand washing section> The filter sand washing section 20 washes the filter sand lifted by the air lift air of the air lift pump 10, and is mainly composed of a separator 21 and a washer 22.

[0022] <Separator> The separator 21 is disposed on the upper end side of the air lift pipe 11. The separator 21 is made of a lid-like body with an opening at the bottom so as to cover the upper opening of the air lift pipe 11. Water (washing wastewater) is transported together with filter sand through the air lift pipe 11 to the separator 21 by the action of the air lift air. The separator 21 is configured to separate the filter sand from the washing wastewater by causing the filter sand entrained with the washing wastewater to settle together with the air lift air.

[0023] <Cleaning device> The washer 22 is disposed below the separator 21. The washer 22 is made of a cylindrical body extending between the separator 21 and the filtration layer 3. The washer 22 has a filter sand introduction part 22a that opens upward, a filtrate water introduction part 22b that opens downward, and a labyrinth passage 22c formed between the filter sand introduction part 22a and the filtrate water introduction part 22b.

[0024] <Cleaning air blowing means> The cleaning air blowing means 50 mainly includes a flow control valve 51, a flow meter 53, a joint 55, and the required (two in this example) cleaning air injection pipes 57, in addition to the air compressor 12 as a supply source of cleaning air. Note that in this example, two cleaning air injection pipes 57 are used, but this is not limited thereto, and there are also embodiments in which one or three or more cleaning air injection pipes 57 are used. When one cleaning air injection pipe 57 is used, the joint 55 can be omitted. When three or more cleaning air injection pipes 57 are used, for example, a centralized distribution joint may be used to distribute compressed air to each cleaning air injection pipe 57.

[0025] The flow control valve 51 has a valve opening controlled in response to a valve opening signal from a control device 70, which will be described later. The flow control valve 51 is connected to the air compressor 12 via an air supply pipe 61 that extends so as to branch off from a portion of the air supply pipe 15 between the air compressor 12 and the flow control valve 16. The flow control valve 51 and a joint 55 are connected via an air supply pipe 62. A flow meter 53 is provided in the air supply pipe 62. The joint 55 and each cleaning air injection pipe 57 are connected via the air supply pipe 63.

[0026] <Cleaning air jet tube> The cleaning air injection pipe 57 is made of a straight pipe member extending obliquely upward toward the filtered water introduction part 22b in the cleaner 22, and is disposed so as to function as an injection nozzle that injects cleaning air (compressed air) toward the filtered water introduction part 22b. The cleaning air injection pipe 57 is supported in a fixed state to the cleaner 22 by a support means such as a stay (not shown).

[0027] <Turbidity meter> A washing drainage reservoir 25 for temporarily storing washing drainage is formed around the separator 21. A turbidimeter 65 is disposed in the washing drainage reservoir 25 so as to measure the turbidity of the stored washing drainage. Examples of the turbidimeter 65 include a transmitted scattered light type, a surface scattered light type, an integrating sphere type, a transmitted light type, a scattered light type, a particle number measurement type, and the like, and any type may be used.

[0028] <Control device> The filtration device 1 further includes a control device 70 that is mainly composed of a computer capable of controlling the entire device. The flow control valves 16, 51, the flow meters 17, 53, and the turbidity meter 65 are connected to the control device 70 so as to be capable of transmitting signals thereto.

[0029] The control device 70 has a timer control circuit 71 and is configured to send a valve opening operation signal to the flow control valve 51 to open the flow control valve 51 when the timer set time Ts by the timer control circuit 71 is exceeded.

[0030] In the filtration device 1 configured as described above, the control device 70 transmits a valve opening operation signal to the flow control valve 16, reads the measurement signal of the flow meter 17, calculates the valve opening of the flow control valve 16 so as to bring the current flow rate of compressed air (air for air lift) closer to the target value, and transmits a valve opening signal based on the calculated valve opening to the flow control valve 16. As a result, the flow control valve 16 is opened at a valve opening corresponding to the valve opening signal from the control device 70.

[0031] In the air lift pump 10, compressed air (air for air lift) is supplied from the air compressor 12 to the inside of the box 13 through the air supply pipe 15 at a flow rate corresponding to the valve opening of the flow control valve 16. The air for air lift supplied to the inside of the box 13 is blown into the inside of the air lift pipe 11 as shown by the arrow E in Fig. 1. Then, as shown by the arrow F in Fig. 1, the water and filter sand at the bottom of the filter tank 2 are sucked up into the inside of the box 13 through the suction pipe 14. The filter sand sucked up into the inside of the box 13 rises as shown by the arrow G in Fig. 1 due to the upward force generated by the difference in specific gravity between the inside and outside of the air lift pipe 11, and is agitated and washed by the air and water during the upward movement.

[0032] <Filter sand washing process> The filter sand, which is raised together with the water (washing wastewater) by the air for airlift, is transported to the separator 21. In the separator 21, the filter sand is allowed to settle, as shown by the arrow H in FIG. 1, to separate the filter sand from the washing wastewater. The filter sand separated in the separator 21 is introduced into the labyrinth passage 22c through the filter sand introduction section 22a in the washer 22. As shown by the arrow I in FIG. 1, a part of the filtrate water that has passed through the filtration layer 3 is introduced into the labyrinth passage 22c as washing water through the filtrate water introduction section 22b. In the labyrinth passage 22c, the filter sand introduced from the filter sand introduction section 22a and the washing water (filtrate water) introduced from the filtrate water introduction section 22b are brought into countercurrent contact with each other, so that the filter sand and the SS are separated, and the filter sand is regenerated as a filter medium. The regenerated filter sand is returned to the filtration layer 3, as shown by the arrow J in FIG. 1. The SS moves upward inside the washer 22 together with the upward flowing water and is temporarily stored in the wash drain reservoir 25 together with the wash drainage water separated and treated in the separator 21. The wash drainage water containing SS stored in the wash drain reservoir 25 passes through holes in the orifice plate 26 constituting one side wall of the wash drain reservoir 25 and / or overflows the orifice plate 26, and is discharged to the outside of the apparatus via a wash drain pipe 27, as shown by symbol K in Fig. 1. Note that reference symbol 28 in Fig. 1 denotes an air vent pipe.

[0033] <Cleaning air blowing process> When the timer set time Ts by the timer control circuit 71 is exceeded, the control device 70 transmits a valve close operation signal to the flow control valve 16 to close the flow control valve 16, stops the operation of the air lift pump 10, and temporarily suspends the processing operation for regenerating the filter media (the filtration processing in the filtration layer 3 due to the inflow of raw water continues). Shortly thereafter, the control device 70 transmits a valve open operation signal to the flow control valve 51 to open the flow control valve 51. As a result, compressed air from the air compressor 12 is supplied as cleaning air to the cleaning air injection pipe 57 via the air supply pipes 61, 62, and 63, and the cleaning air is injected toward the filtrate water introduction part 22b in the scrubber 22. The injected cleaning air is blown from the filtrate water introduction part 22b into the inside of the scrubber 22, i.e., into the labyrinth passage 22c, and is blown into the inside of the separator 21 through the labyrinth passage 22c. As a result, even if foreign matter or the like adheres to and accumulates as dirt in the filtration sand washing section 20 (separator 21, washer 22) as the operation time of the filtration device 1 progresses, it is blown off by the cleaning air and peeled off and removed. The peeled off and removed foreign matter or the like is temporarily stored in the washing drainage reservoir 25 together with the washing drainage water separated and processed in the separator 21, and then, like the SS, passes through the holes in the orifice plate 26 and / or overflows the orifice plate 26, and is discharged to the outside of the device via the washing drainage pipe 27 as shown by symbol K in FIG. 1. In this way, clogging of the filtration sand washing section 20 can be prevented. In addition, the separator 21 and the washer 22 are simultaneously washed by the cleaning air injected from the cleaning air injection pipe 57, so that the cleaning efficiency can be improved.

[0034] After the predetermined time has elapsed, the control device 70 transmits a valve close signal to the flow control valve 51 to close the flow control valve 51, stop the cleaning operation of the filtration sand washing section 20, reset the timer set time Ts by the timer control circuit 71, and start counting again. In addition, the control device 70 transmits a valve open signal to the flow control valve 16 to open the flow control valve 16 and restart the operation of the air lift pump 10.

[0035] However, for example, depending on the operating conditions of the pretreatment equipment (not shown) installed upstream of the filtration device 1, the SS concentration of the raw water may suddenly rise. In this case, the possibility of foreign matter adhering and accumulating in the filtration sand washing section 20 increases. Therefore, when the measurement value of the turbidity meter 65 reaches or exceeds a predetermined value, even if the timer set time Ts by the timer control circuit 71 has not been exceeded, the control device 70 transmits a valve close operation signal to the flow control valve 16 to close the flow control valve 16 and stop the operation of the air lift pump 10, and transmits a valve open operation signal to the flow control valve 51 to open the flow control valve 51. Then, the control device 70 reads the measurement signal of the flow meter 53 and the measurement signal of the turbidity meter 65, calculates the valve opening degree of the flow control valve 51 so that the current flow rate of the compressed air (cleaning air) approaches a target value, which is a required flow rate according to the turbidity, and transmits a valve opening degree signal based on the calculated valve opening degree to the flow control valve 51. As a result, the flow control valve 51 is opened at a valve opening according to the valve opening signal from the control device 70, and even if the SS concentration of the raw water fluctuates greatly, an appropriate amount of cleaning air can be blown in, neither too much nor too little, depending on the degree of contamination.

[0036] By repeating the above-described filter medium regeneration process and the cleaning operation of the filter sand washing section 20, the filtration device 1 can be operated stably for a long period of time.

[0037] The filtration device and the operating method of the filtration device of the present invention have been described above based on one embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and the configuration can be appropriately changed without departing from the spirit of the present invention.

[0038] (Another embodiment) FIG. 2 is a schematic diagram showing an enlarged view of a main part of the filtration device 1 according to another embodiment of the present invention. In the above embodiment, the cleaning air blowing means 50 includes a straight cleaning air injection pipe 57 arranged to inject cleaning air toward the filtered water introduction part 22b in the cleaner 22, but the present invention is not limited to this. As shown in FIG. 2, the cleaning air injection pipe 57 may be an annular pipe arranged near the filtered water introduction part 22b and having a circular cross section and a circular ring shape in a plan view. The cleaning air injection pipe 57 shown in FIG. 2 is supported in a fixed state on the cleaner 22 by a support means such as a stay (not shown). In the cleaning air injection pipe 57, required injection holes 57a opening toward the filtered water introduction part 22b are drilled at a predetermined pitch in the circumferential direction at the upper part near the inner circumference, and the cleaning air supplied from the air compressor 12 through the air supply pipes 61, 62, and 63 can be injected from the injection holes 57a toward the filtered water introduction part 22b. The cross-sectional shape of the cleaning air injection pipe 57 is not limited to a circle, and may be, for example, an ellipse or a polygon. The planar shape of the cleaning air injection pipe 57 is not limited to a circular ring, and may be, for example, an ellipse or a polygon. The other embodiment shown in Fig. 2 can of course obtain the same effects as the embodiment shown in Fig. 1, and can omit the joint 55 required in the embodiment shown in Fig. 1 and can reduce the number of air supply pipes 63 compared to the embodiment shown in Fig. 1, thereby simplifying the device configuration. [Industrial Applicability]

[0039] The filtration apparatus and the method for operating the filtration apparatus of the present invention can be used in water treatment applications such as sewage, drinking water, and general wastewater. [Explanation of symbols]

[0040] 1. Filtration equipment 3. Filtration layer 10 Air lift pump 20 Filter sand washing section 21 Separator 22 Cleaning machine 50 Cleaning air blowing means 57 Cleaning air jet pipe 65 Turbidity meter 70 Control device

Claims

1. A filtration device configured to filter raw water by flowing the raw water upward through a filtration layer formed by filling filtration sand, and to discharge water that is raised together with the filtration sand by air lift air supplied to the filtration layer by an air lift pump as washing wastewater, A filtration sand washing unit that washes the filtration sand lifted by the air for the air lift; A cleaning air blowing means for blowing cleaning air into the filter sand washing section; Equipped with The filtration sand washing section includes: A separator for separating the filter sand; a washer into which the filtration sand separated by the separator and filtrate water that has passed through the filtration layer are introduced and the filtration sand and the filtrate water are brought into countercurrent contact with each other to wash the filtration sand; Including, The cleaning air blowing means is a filtering device including a cleaning air injection pipe arranged to inject cleaning air toward a filtered water inlet portion of the cleaner into which the filtered water is introduced.

2. A filtration device configured to filter raw water by flowing the raw water upward through a filtration layer formed by filling the filtration sand, and to discharge water that is raised together with the filtration sand by air lift air supplied to the filtration layer by an air lift pump as cleaning wastewater, A filtration sand washing unit that washes the filtration sand lifted by the air for the air lift; A cleaning air blowing means for blowing cleaning air into the filter sand washing section; A turbidity meter for measuring the turbidity of the cleaning wastewater; a control device that controls the amount of cleaning air blown by the cleaning air blowing means based on the measurement value of the turbidity meter; A filtration device comprising:

3. A method for operating a filtration device configured to filter raw water by flowing the raw water upward through a filtration layer formed by filling filtration sand, and to discharge water that is raised together with the filtration sand by air lift air supplied to the filtration layer by an air lift pump as washing wastewater, A filtration sand washing step in which the filtration sand lifted by the air for airlift is washed in a filtration sand washing section; A cleaning air blowing step of blowing cleaning air into the filter sand washing section; Inclusive of A method for operating a filtration device, comprising measuring the turbidity of the cleaning wastewater and controlling the amount of cleaning air blown in based on the turbidity of the cleaning wastewater.

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