JP4650373B2 - Continuous operation method of long fiber filter - Google Patents

Description

  The present invention relates to a continuous operation method of a long fiber filtration device.

  The long fiber filtration device accommodates a filter medium of a long fiber bundle in a tower, supplies raw water in a downward flow format and supplies wash water in an upward flow format, and when the raw water is supplied, the filter media forms a compacted state and It has a structure that can release the compacted state when supplying wash water, is effective in removing turbidity in raw water, and is sometimes called a turbidity removal device (Patent Document 1).

Conventionally, as an operation method of the long fiber filtration device (turbidity removal device), with respect to the washing operation, the washing water is not supplied for a long time by one washing operation, but by the operation of extracting the stored water in the tower. An improved continuous operation method has been proposed in which multiple cleaning operations are performed and air is supplied together with cleaning water to enhance the cleaning effect, and usually three cleaning operations are performed (patent) Reference 1).
Japanese Patent Laid-Open No. 2003-53113

Meanwhile, raw water subjected to the removal of suspended solid (surface water, river water, ground water, a mixture thereof water), as an impurity, containing organic substances such as humic acids, fulvic acids, their salts, they slip in the filter medium It adheres as a component and causes problems such as an increase in pressure loss. And it is difficult to remove the adhering components as described above by ordinary physical cleaning.

  The present invention has been made in view of the above circumstances, and the purpose of the present invention is to provide a continuous continuous fiber filtration device improved so that efficient cleaning can be performed with a relatively small amount of cleaning water by improving the cleaning operation. It is to provide a driving method.

  That is, the gist of the present invention is that the filter medium of the long fiber bundle is accommodated in the tower, the raw water is supplied in the downward flow format and the washing water is supplied in the upward flow format, and the filter media forms a consolidated state when the raw water is supplied. In addition, the operation method of the long fiber filtration device having a structure capable of releasing the compacted state when supplying the cleaning water, and repeatedly performing the raw water treatment operation and the cleaning operation in which the following operations (i) to (v) are sequentially performed. In the continuous operation method of the long fiber filtration apparatus characterized by these.

(I) Supply wash water to release the compacted state of the filter medium.
(Ii) Supply washing water and air to remove 90% by weight or more of the suspended matter trapped in the filter medium.
(Iii) Drain the stored water.
(Iv) Supplying wash water, an alkali component and air, and at least the entire filter medium in the tower is immersed in the alkali component-containing wash water having a concentration of 0.01 to 1% by weight. Leave it to dissolve the organic matter adhering to the filter medium.
(V) Supply washing water and air to remove alkali components.

  According to the continuous operation method of the long fiber filtration device according to the present invention, an increase in pressure loss can be reduced and stable continuous operation can be performed over a long period of time.

  Hereinafter, the present invention will be described in detail. The structure of the long fiber filtration device used in the present invention is that the filter medium of the long fiber bundle is accommodated in the tower, the raw water is supplied in the downward flow format, and the cleaning water is supplied in the upward flow format. Any structure may be used as long as it has a structure capable of forming a consolidated state and releasing the consolidated state when supplying cleaning water.

  FIG.1 and FIG.2 is typical explanatory drawing of an example of the long-fiber filtration apparatus which can be used suitably by this invention, A fraction (a) is explanatory drawing of a raw-water-treatment operation state, Minute (b)-(d) ) Is an explanatory diagram of a cleaning operation state. This long fiber filtration device is basically the same as the turbidity removal device described in the above-mentioned prior art (Japanese Patent Laid-Open No. 2003-53113).

  The above-mentioned long fiber filtration device is configured as follows. That is, a raw water supply pipe with a valve and a cleaning waste water discharge pipe are provided at the top of the tower (1), and a treated water discharge pipe with a valve, a cleaning water supply pipe and a valve are provided at the bottom of the tower (1). Air supply pipe, a drain pipe with a valve and an alkaline water supply pipe with a valve are provided, and an upper support (2) and a lower support (3) are arranged inside the tower, and an upper support (2) A plurality of filter media (4) made of a core string and a turbidity trapping material projecting from the periphery of the core string are provided between the upper support string (7) and the lower support (3). ) And the lower suspension string (8) are fixed in a suspended state, and the core string of the filter medium (4) and the upper suspension string (7) and the lower suspension string (8) are configured to be bent and deformable along the flowing water direction. The distance (LA) between the upper support (2) and the lower support (3), the length of the filter medium (4) ( B), the length of the upper hanging strap (7) (Lb1), the formula (1 relationship between the length of the lower hanging strap (8) (Lb2) are defined below) satisfies to (3).

  The structure of the upper support (2) and the lower support (3) is not particularly limited as long as it is a structure that does not prevent water flow and can fix the filter medium (4) by the hanging strings (7) and (8). For example, a lattice structure, an eye plate structure, a stitch structure, or the like can be appropriately employed.

  The filter medium (4) includes a core string and a turbidity trapping material protruding on the peripheral side of the core string. The core string of the filter medium (4), the upper suspension string (7), and the lower suspension string (8) are configured to be bent and deformed along the flowing water direction. Such a configuration is achieved by selecting the type, form, thickness, etc. of the material.

  Each of the above elements is usually composed of a synthetic resin material such as polypropylene, polyester, nylon, or polyvinylidene chloride. In addition to the various cords obtained by each process of assembling, twisting, knitting, weaving, bundling, rake, or cutting, each of the above-mentioned cords should use a single yarn (monofilament) as long as it has sufficient strength. I can do it. Moreover, the shape of the turbidity trapping material of the filter medium (4) is usually a film piece or a thread. As an example of the filter medium (4), a filter medium in which an innumerable thread-like turbidity trapping material is radially projected on the peripheral side of the twisted core string. Such a filter medium is known as described in JP-A-8-299707. In addition, when the core string of the filter medium (4) is long and protrudes from both ends of the projecting range of the turbidity trapping material, the core strings of the protruding parts at both ends are used as the upper suspension string (7) and the lower suspension string (8). You can also

  In the long fiber filtration device, as shown in the formula (1), the total length (Lb1 + LB + Lb2) of the filter medium (4), the upper support (2), and the lower support (3) is the upper support (2 ) And the lower support (3) is longer than the distance (LA). Accordingly, any of the above elements exists in a relaxed state in the tower (1).

Moreover, as shown in Formula (2), the distance (LA) between the upper support (2) and the lower support (3) is longer than the length (LB) of the filter medium (4). Therefore, a region where the filter medium (4) does not exist is formed along the flowing water direction between the upper support (2) and the lower support (3). Words to lever, the movable range of the filter medium (4) along the flowing water direction is formed. In addition, although the clearance gap exists between filter media (4) in the schematic explanatory drawing of FIG. 1, there is actually no clearance gap between filter media (4), and several filter media (4) will be in a dense state. Suspended. Therefore, the whole of the plurality of filter media (4) moves only along the flowing water direction (vertical direction).

  Furthermore, as shown in Formula (3), the total length (LB + Lb1) of the filter medium (4) and the upper suspension string (7) is the total length (LB + Lb2) of the filter medium (4) and the lower suspension string (8). ) Longer. Accordingly, during raw water treatment operation in which raw water is supplied in a downward flow format, as shown in FIG. 1 (a), the filter medium (4) abuts on the lower support (3) and lower suspension string (8). At the same time, the filter medium (4) is brought into contact with the upper support (2) as shown in FIG. Without it, it will be in the state extended to the upper part in a tower with a lower suspension string (8).

  As a result of the above, in the above-described long fiber filtration device, trapping and discharging of turbidity by the filter medium can be efficiently performed by releasing the compacted state of the filter medium during the raw water treatment operation and releasing the compacted state of the filter medium during the washing operation. Is called. In addition, the numerical value of the magnitude relationship of each element prescribed | regulated by said Formula (1)-(3) is a value determined in consideration of the economical efficiency of the apparatus.

  The dimensions of the above-mentioned elements of the long fiber filtration device are as follows. That is, the distance (LA) between the upper support (2) and the lower support (3) is 100 to 400 cm, the length (LB) of the filter medium (4) is 70 to 300 cm, and the upper suspension string (7) The length (Lb1) is 10 to 250 cm, the length (Lb2) of the lower suspension string (8) is 5 to 20 cm, and the diameter (inner diameter) of the tower (1) is 20 to 360 cm.

  The continuous operation method of the above-mentioned long fiber filtration apparatus consists of repeatedly performing the raw water treatment operation and the washing operation. In the apparatus shown in FIG. 1, a T-shaped pipe (51) provided at the top of the tower (1) and provided with valves (61) and (65) is used as a raw water supply pipe during a raw water treatment operation, and is washed. A T-shaped pipe (52) provided at the bottom of the tower (1) and provided with valves (64) and (62) is a common pipe used as a washing waste water discharge pipe during operation. This is a common pipe used as a treated water discharge pipe during operation and as a wash water supply pipe during cleaning operation, and the direction of water flow is changed by valve operation. An air supply pipe (53), a drain pipe (54), and an alkaline water supply pipe (55) are branched from the pipe (52). In the following description, each of the above pipes is simply referred to as “pipe”.

<Raw water treatment operation: See FIG. 1 (a)>
In the raw water treatment operation, only the valves (61) and (62) are opened. Raw water containing turbidity is supplied into the tower (1) via a valve (61) and a pipe (51). At this time, the filter medium (4) is in a compacted state as described above, and the suspended matter entrained in the raw water is captured by the filter medium (4). The treated water containing no turbidity is discharged from the tower (1) via the pipe (52) and the valve (62). In the raw water treatment operation, for example, the raw water treatment operation is stopped when the performance of the long fiber filtration device is lowered by means such as pressure measurement of a raw water supply pump (not shown) and water quality analysis of the treated water. The stop of the raw water treatment operation may be automatically performed every certain time.

<Washing operation>
The washing operation according to the present invention comprises sequentially performing the following operations (i) to (v). The cleaning water used for the cleaning operation may be either raw water or treated water. In addition, the raw water and the treated water are properly used for each operation. For example, the treated water may be used only for the final operation (v).

[Operation (i): See FIG. 1 (b))]
This operation is an operation for releasing the compacted state of the filter medium by supplying cleaning water. In this operation, the valves (61) and (62) that were open during the raw water treatment operation are closed, and only the valves (64) and (65) are opened. The washing water is supplied into the tower (1) via the valve (64) and the pipe (52). The filter medium (4) is released from the compacted state as described above, and a part of the suspended matter captured by the filter medium (4) is removed. Washing wastewater containing turbidity is discharged from the tower (1) via the pipe (51) and the valve (65). The operation (i) needs to be performed at least until the lower suspension strap (8) and the filter medium (4) extend upward in the tower. However, the operation for a long time until the turbidity concentrated on the upper part of the filter medium (4) is removed is uneconomical because it uses a large amount of washing water, so it is not necessary to perform it. The washing water supply rate (LV) is usually 25 to 80 m / h, and the washing water supply time is usually 0.5 to 2 minutes.

[Operation (ii): See FIG. 1 (b)]
This operation is an operation for removing 90% by weight or more of the suspended matter trapped in the filter medium by supplying washing water and air. That is, in addition to the state of the above operation (i), the valve (63) is opened to start supplying air. Air is supplied into the tower (1) via a valve (63) and a pipe (53). Of course, after the operation (i) has been completed, the supply of cleaning water and air may be started. In this case, the supply of air may be started simultaneously with the supply of the cleaning water, or may be started later than the supply of the cleaning water. The bubbling action of the air causes the filter medium (4) to vibrate, and the separation of turbidity adhering to the filter medium (4) is promoted. The washing waste water is discharged from the tower (1) via the pipe (51) and the valve (65).

  In operation (ii), the washing water supply speed (LV) is usually 25 to 80 m / h, the washing water supply time is usually 2 to 10 minutes, the air supply speed (LV) is usually 200 to 500 m / h, air The supply time is usually 0.5 to 2 minutes.

  Since the removal of turbidity trapped in the filter medium depends on the supply amount (supply time) of washing water and air, the removal of 90% by weight or more of the turbidity trapped in the filter medium is the washing water obtained by preliminary experiments. And can be achieved by supplying the required supply of air.

  However, it is convenient to employ a method of supplying cleaning water and air until the turbidity of the cleaning wastewater reaches the same level as that of the raw water. The turbidity can be measured, for example, by installing a turbidimeter (not shown) downstream of the valve (65). As the turbidity to be measured, it is preferable to adopt the turbidity specified in JIS K 0101. This index defines the turbidity of a solution of 1 mg / l kaolin as 1 degree. There are transmitted light turbidity, scattered light turbidity, and integrated light turbidity due to the difference in measurement principle. do it.

[Operation (iii): See FIG. 2 (c)]
This operation is an operation for extracting the stored water in the tower (1). That is, with the completion of the operation (ii), the valves (63) and (64) are closed, and then the valve (66) is opened. The stored water is discharged from the tower (1) via the pipe (54) and the valve (66). By this operation, the filter medium (4) forms a consolidated state by its own weight. Air leaks into the tower (1) via the pipe (51) and the valve (65), and the inside of the tower (1) is maintained at atmospheric pressure.

[Operation (iv): See FIG. 2 (d)]
This operation supplies washing water, an alkali component and air, and supplies the above after at least the entire filter medium (4) in the tower (1) is immersed in the alkali component-containing washing water having a concentration of 0.01 to 1% by weight. Is stopped and left for 1 minute or longer to dissolve the organic matter adhering to the filter medium (4). In this operation, the valve (66) that was open during the above operation (iii) is closed, and then the valves (63), (64), and (67) are opened. The washing water is supplied via the valve (64) and the pipe (52), the alkaline component (high concentration aqueous solution) is supplied via the valve (67) and the pipe (55), and the air is supplied to the valve ( 63) and the pipe (53). Examples of the alkali component include aqueous solutions of sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, ammonium hydroxide, and the like. In the following description, the standing time after the supply is stopped is described as “filter material immersion time”.

In operation (iv), the washing water supply speed (LV) is usually 20 to 80 m / h, the washing water supply time is usually 0.5 to 2 minutes, and the air supply speed (LV) is usually 200 to 500 m / h. The air supply time is usually 0.5 to 2 minutes. The supply amount of the alkali component (high concentration aqueous solution) is adjusted so that the concentration of the alkali component in the tower (1) is in the range of 0.01 to 1% by weight.
When the concentration of the alkali component is too low, it takes a long time to dissolve the organic matter adhering to the filter medium (4), and when the concentration of the alkali component is too high, the alkali component is wasted, and in either case, it is economical. Not right.

  By the operation (iv), the filter medium (4) is released from the compacted state, and organic substances attached to the filter medium (4) are dissolved and removed. The supply of air may be started simultaneously with the supply of cleaning water, or may be started later than the supply of cleaning water. By the bubbling action of air, the filter medium (4) is vibrated, and the dissolution of the organic matter attached to the filter medium (4) is promoted. In operation (iv), it is economical and preferable to stop the supply of washing water and alkali components and air after the inside of the tower (1) is filled with washing water containing alkali components.

  The upper limit of the filter medium soaking time in operation (iv) depends on the amount of organic matter (slip component) attached to the filter medium (4), but is usually one day. In addition, when immersion time is long, in order to prevent the non-uniform | heterogenous density | concentration of the alkali component in a tower (1), it is preferable to restart supply of air and to mix the inside of a tower (1).

[Operation (v)]
This operation is an operation of supplying washing water and air to remove alkali components. That is, the valve (67) opened by the above operation (iv) is closed. Of course, the supply of cleaning water and air may be started after the operation (iv) has been completed. In this case, the supply of air may be started simultaneously with the supply of the cleaning water, or may be started later than the supply of the cleaning water. The filter medium (4) is vibrated by the bubbling action of air, and the removal of the alkali component adhering to the filter medium (4) is promoted. The washing waste water is discharged from the tower (1) via the pipe (51) and the valve (65). The operation (v) is preferably performed, for example, by installing an alkali concentration meter (not shown) downstream of the valve (65) until no alkali component is detected in the washing waste water.

  In operation (v), the washing water supply speed (LV) is usually 20 to 80 m / h, the washing water supply time is usually 2 to 10 minutes, the air supply speed (LV) is usually 200 to 500 m / h, air Is usually 2 to 10 minutes.

  In the present invention, the raw water treatment operation described above is repeated after the cleaning operation in which the above operations (i) to (v) are sequentially performed is terminated. According to the present invention, the slip component adhering to the filter medium can be efficiently removed, and by removing the slip component, an increase in pressure loss can be reduced and stable operation can be performed over a long period of time.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example, unless the summary is exceeded.

Example 1:
A continuous operation of a long fiber filtration apparatus having the illustrated structure and having the specifications shown in Table 1 below was performed. River water was used as raw water and treated water was used as washing water.

<Raw water treatment operation>
Only valves (61) and (62) were opened. The raw water containing turbidity is supplied into the tower (1) via the valve (61) and the pipe (51), and the treated water not containing turbidity is sent via the pipe (52) and the valve (62). Was discharged from the tower (1). Raw water treatment operation was performed at a water flow rate of 4.24 m ³ / h. Then, the pressure of the raw water supply pump (not shown) is measured, the time when the differential pressure reaches 0.1 MPa is set as the water end point, the water flow is stopped, and the cleaning comprising the following (i) to (v) After the operation, the same raw water treatment operation as described above was performed.

<Washing operation>
[Operation (i): See FIG. 1 (b))]
The valves (61) and (62) that were open during the raw water treatment operation were closed, and only the valves (64) and (65) were opened. The wash water is supplied into the tower (1) via the valve (64) and the pipe (52), and the washing waste water containing turbidity is supplied to the tower (1) via the pipe (51) and the valve (65). ). The supply rate (LV) of the cleaning water was 50 m / h, the supply time of the cleaning water was 0.5 minutes, and the supply amount of the cleaning water was 3.5 m ³ / h.

[Operation (ii): See FIG. 1 (b)]
In addition to the state of the operation (i), the valve (63) was opened to start supplying air. Air was supplied into the tower (1) via the valve (63) and the pipe (53), and the washing wastewater was discharged from the tower (1) via the pipe (51) and the valve (65). . The cleaning water supply rate (LV) was 50 m / h, the cleaning water supply time was 7 minutes, and the cleaning water supply amount was 3.5 m ³ / h. The air supply rate (LV) was 500 m / h, the air supply time was 7 minutes, and the air supply amount was 35 m ³ / h. Then, it was confirmed by a turbidimeter downstream of the valve (65) that the turbidity of the washing wastewater reached the same level as the turbidity of the raw water. The turbidity was measured by integral light turbidity according to JIS K 0101.

[Operation (iii): See FIG. 2 (c)]
Upon completion of the operation (ii), the valves (63) and (64) were closed, and then the valve (66) was opened. The stored water was discharged from the tower (1) via the pipe (54) and the valve (66).

[Operation (iv): See FIG. 2 (d)]
After the valve (66) that was open during the operation (iii) was closed, the valves (63), (64), and (67) were opened. The washing water is supplied via the valve (64) and the pipe (52), the alkaline component (high concentration aqueous solution) is supplied via the valve (67) and the pipe (55), and the air is supplied to the valve ( 63) and piping (53). As the alkali component (high concentration aqueous solution), a sodium hydroxide aqueous solution (48% by weight) was used. The cleaning water supply rate (LV) was 50 m / h, the cleaning water supply time was 2 minutes, and the cleaning water supply amount was 3.5 m ³ / h. The air supply speed (LV) was 500 m / h, and the air supply time was 2 minutes. The supply amount of the alkali component (high concentration aqueous solution) was adjusted so that the concentration of the alkali component in the tower (1) was 0.02% by weight. The filter medium immersion time was 4 minutes. In addition, the supply of air was resumed for 1 minute in the middle of the above-mentioned filter medium immersion time.

[Operation (v)]
The valve (67) opened in the above operation (iv) was closed. The cleaning water supply rate (LV) was 50 m / h, the cleaning water supply time was 5 minutes, and the cleaning water supply was 3.5 m ³ / h. The air supply rate (LV) was 500 m / h, the air supply time was 5 minutes, and the air supply amount was 35 m ³ / h. Then, it was confirmed that an alkali component in the cleaning wastewater was not detected by an alkali concentration meter (not shown) installed downstream of the valve (65).

  The raw water treatment operation and the washing operation were repeated, and the turbidity (NTU turbidity) of the treated water was continuously measured, and the results are shown in FIG.

Comparative Example 1:
In Example 1, the raw water treatment operation and the washing operation were repeated in the same manner as in Example 1 except that the supply of the alkaline component (high-concentration aqueous solution) was stopped in the operation (iv) of the washing operation. Turbidity (NTU turbidity) was measured continuously, and the results are shown in FIG.

Schematic explanatory diagram of an example of a long fiber filtration device that can be suitably used in the present invention Schematic explanatory diagram of an example of a long fiber filtration device that can be suitably used in the present invention The graph which shows the measurement result of the turbidity of the treated water obtained in Example 1 The graph which shows the measurement result of the turbidity of the treated water obtained in Comparative Example 1

Explanation of symbols

1: Tower 2: Upper support 3: Lower support 4: Filter medium 7: Upper suspension string 8: Lower suspension string 51-55: Piping 61-67: Valve

Claims (3)

The filter medium of the long fiber bundle is accommodated in the tower, the raw water is supplied in the downward flow format, and the cleaning water is supplied in the upward flow format. When the raw water is supplied, the filter media forms a consolidated state and when the cleaning water is supplied, it is in the consolidated state. Is a method for operating a long-fiber filtration device having a structure capable of releasing the raw water, wherein the raw water treatment operation and a washing operation in which the following operations (i) to (v) are sequentially performed are repeated. Continuous operation method.
(I) Supply wash water to release the compacted state of the filter medium.
(Ii) Supply washing water and air to remove 90% by weight or more of the suspended matter trapped in the filter medium.
(Iii) Drain the stored water.
(Iv) Supplying wash water, an alkali component and air, and at least the entire filter medium in the tower is immersed in the alkali component-containing wash water having a concentration of 0.01 to 1% by weight. Leave it to dissolve the organic matter adhering to the filter medium.
(V) Supply washing water and air to remove alkali components.   The continuous operation method according to claim 1, wherein in the operation (ii) of the cleaning operation, the cleaning water and the air are supplied until the turbidity of the cleaning wastewater reaches the same level as the turbidity of the raw water.   The continuous operation method according to claim 1 or 2, wherein in the operation (v) of the cleaning operation, the cleaning water and air are supplied until no alkaline component is detected in the cleaning wastewater.