JP5145384B2 - Operation method of filtration facility - Google Patents

Description

  The present invention relates to a method for operating a water treatment facility including a gravity filtration device using a particulate filler such as an activated carbon filtration device (activated carbon adsorption device) or a sand filtration device.

  In water purification treatment at a water purification plant, raw water to be treated is temporarily stored in a raw water tank, a certain amount of raw water is taken out from the raw water tank, and solid-liquid separation treatment, biological treatment or adsorption treatment is performed by a treatment device such as a filtration device. To do. These treated waters are further sterilized to produce drinking water. In order to send raw water from the raw water tank to the filtration device, a pump may be used, but there is also a gravity filtration device that is a water supply method that does not use power.

  In many cases, the gravity type filtration device is a filtration device filled with granular activated carbon, anthracite, ceramic or sand as a filler. In such a filtration device, depending on the type or specification of the filler used, solid matter contained in the raw water is filtered, soluble substances are removed by adsorption, or microorganisms propagated around the granular filler. It is purified by being biologically decomposed.

  Here, in patent document 1, in the filtration processing equipment provided with a plurality of filtration ponds, by reusing the waste water after washing the filtration pond, the water recovery rate of the water purification plant is improved, and from the waste water operation. A filter basin operation method for smoothly switching to the filtration operation is disclosed.

JP 11-47511 A

  Unlike the case of supplying raw water with a pump, a gravity filtration device using granular or spherical activated carbon, anthracite, ceramic, or sand as a filler is different from the original method in order to keep the filtration rate (treatment rate) within a certain range. It is necessary to keep the amount of raw water in the tank within a certain range. In particular, in the case of an upward flow type gravity filtration device, if the filtration rate is lowered, the development of the filler particles becomes insufficient, and the treatment capacity of the raw water may be greatly reduced. If for some reason the amount of raw water in the raw water tank decreases, if you want to keep the filtration speed within a certain range, you need to prepare multiple gravity filtration devices and reduce the number of gravity filtration devices to be operated. .

However, it is difficult to continuously adjust the filtration rate per gravity filtration device within a certain range because the amount of treated water per unit is determined only by reducing the number of gravity filtration devices. is there. Moreover, although the operation method currently disclosed by patent document 1 collect | recovers the waste water after back washing operation of a filter basin to a raw water tank with a waste water pump, this operation method is the filtration speed | rate of a filter basin (filter apparatus). Cannot be adjusted.

  The present invention is directed to a filtration facility for filtering raw water using a gravity filtration device. Even if the amount of raw water is changed to a water amount other than an integral multiple of the treated water amount per filtration device, gravity filtration An object of the present invention is to provide an operation method capable of adjusting the change in filtration rate per apparatus within a substantially constant range.

  The inventor has intensively studied to solve the above problems. As a result, in a filtration facility equipped with a plurality of gravity filtration devices, in addition to adjusting the number of gravity filtration devices to be operated, the treated water in the treatment water tank is appropriately sent to the raw water tank by a pump. It has been found that the change in filtration rate per filtration device can be adjusted within a certain range, and the present invention has been completed.

Specifically, the present invention
Raw water tank,
A plurality of gravity filtration devices for filtering raw water stored in the raw water tank;
A treated water tank for storing treated water of the plurality of gravity filtration devices;
A method for operating a filtration facility comprising:
The gravity filtration device is a gravity filtration device filled with a particulate filler,
A circulation pump is provided for feeding the treated water stored in the treated water tank to the raw water tank,
When the amount of raw water in the raw water tank decreases, the number of operating gravity filtration devices is reduced and / or a part of the treated water in the treated water tank is sent to the raw water tank by the circulation pump. Keep the filtration rate of the gravity filtration device constant by increasing the amount of water to
Thereafter, when the amount of raw water in the raw water tank increases, the number of operating gravity filtration devices is increased and / or a part of the treated water in the treated water tank is transferred to the raw water tank by the circulation pump. And reducing the amount of water to be sent to keep the filtration rate of the gravity filtration device constant.

  The gravitational filtration device is more advantageous when it is an upward flow gravity filtration device. In the case of the downward flow type gravity filtration device, the filler does not flow out even if the filtration rate is excessive, but in the case of the upward flow type gravity filtration device, the filtration rate is excessive. Then, there is a possibility that the filler flows out from the upper part of the filtration device. For this reason, the operation method of the filtration treatment facility of the present invention that can adjust the filtration rate within a substantially constant range is particularly effective when an upward flow type gravity filtration apparatus is used.

  The particulate filler is preferably granular or spherical activated carbon, anthracite, ceramic or sand.

  It is preferable that a plurality of the circulation pumps are provided, and the number of the circulation pumps to be operated and the output thereof are adjusted according to the amount of water supplied to the raw water tank. Regardless of the amount of raw water inflow, in order to adjust the filtration speed within a certain range, the raw water tank is arbitrarily selected according to the deviation between the filtration speed when the treated water is not sent to the raw water tank and the filtration speed when the treated water is sent. This is because it is necessary to change the amount of treated water delivered to the water.

  According to the operation method of the filtration treatment facility of the present invention, in a filtration treatment facility equipped with a gravity filtration device that needs to adjust the filtration speed to a certain range, even if the amount of raw water changes, the filtration of the gravity filtration device The speed can be easily adjusted.

It is a schematic block diagram showing an example of the filtration treatment facility suitable for implementation of the operating method of the present invention. It is a graph showing an example of the driving | running method of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. In addition, this invention is not limited to the following description.

  FIG. 1 is a schematic configuration diagram showing an example of a filtration treatment facility suitable for carrying out the operation method of the present invention. In this filtration treatment facility, raw water (treated water) is taken into the raw water tank 1 through the raw water intake route 21. The raw water 2 stored in the raw water tank is supplied to the lower part of the gravity filtration devices 6a to 6c via the raw water paths 5a to 5c by the water pressure. The raw water paths 5a to 5c are provided with flow control valves 3a to 3c and flow meters 4a to 4c, respectively. In addition, the gravity type filtration apparatuses 6a-6c are demonstrated as an upward flow type gravity filtration apparatus in FIG.

  The gravitational filtration devices 6a to 6c are filled with a particulate filler. The particulate filler is, for example, granular or spherical activated carbon, sand, anthracite, or ceramic particles. Depending on the type or specification of the filler used, solids contained in the raw water are filtered, soluble substances are removed by adsorption, or biologically degraded by microorganisms that have propagated around the particulate filler. The raw water is purified.

  The raw water supplied from the lower part of the gravity filtration devices 6a to 6c is purified by a filter or the like provided according to the particulate filler and the quality of the raw water. The treated water of the gravity filtration devices 6 a to 6 c is taken out from the treated water paths 7 a to 7 c connected to the upper portions of the gravity filtration devices 6 a to 6 c and stored in the treated water tank 8. If the treated water stored in the treated water tank 8 reaches a certain amount, the treated water is sent to the outside of the filtration treatment facility via the treated water supply path 22.

  Here, if the raw water is a river, lake water, groundwater or seawater, the amount of raw water taken from the raw water intake path 21 can be easily adjusted. For example, in the case of factory wastewater, the amount of wastewater is determined by the operational status of the factory, etc. . For this reason, when the amount of drainage changes, the amount of water intake of the raw water tank 1 must be changed according to the amount of drainage. In the case of water supply facilities, it is often difficult to change the amount of raw water from the viewpoint of securing the amount of water supply. If the raw water 2 in the raw water tank 1 increases, the flow rate of the raw water paths 5a to 5c increases, so that an increase in the flow rate can be detected by the flow meters 4a to 4c. And according to the measured value of the flowmeters 4a-4c, the filtration speed (processing speed) of the gravity-type filtration apparatus 6a-6c can be decreased by restrict | squeezing the flow regulating valves 3a-3c.

  Conversely, if the raw water 2 in the raw water tank 1 is reduced, the flow rates of the raw water paths 5a to 5c are also reduced. However, in this case, the flow rates of the raw water paths 5a to 5c cannot be increased even if the flow rate adjustment valves 3a to 3c are opened, except when the flow rate adjustment valves 3a to 3c are originally throttled. That is, the filtration rate of the gravity filtration devices 6a to 6c cannot be increased.

  When the filtration rate of the gravity type filtration devices 6a to 6c is lower than a certain range, the development of the internal filler becomes insufficient, and the treatment capacity of the raw water is lowered. In addition, since the filler is difficult to expand, solids and the like are easily clogged in the vicinity of the bottom surface of the filler.

  In such a case, the water filtration to one or two of the gravity filtration devices 6a to 6c is stopped, and the number of operations is reduced, so that the filtration rate of the gravity filtration devices 6a to 6c being operated is constant. It is conceivable to keep within the range. However, it is difficult to adjust the filtration speed per gravity filtration device only by reducing the number of operating gravity filtration devices 6a to 6c. That is, when the water supply to some of the gravity filtration devices 6a to 6c is stopped when the filtration rate is close to the lower limit value, the filtration rate of the remaining gravity filtration device increases to a target value or more. There is.

  Therefore, in the operation method of the present invention, a part of the treated water 9 stored in the treated water tank 8 is returned to the raw water tank 1 through the water return path 11 by the circulation pump 10 provided in the treated water tank 8. Water (feed water). Even when the number of operating gravity filtration devices 6a to 6c is reduced by returning the treated water 9 to the raw water tank 1, the change in filtration rate per gravity filtration device is within a certain range. It becomes possible to adjust.

  In addition, if there is little decrease amount of the raw | natural water 2 in the raw | natural water tank 1, even when it does not reduce the number of operation of gravity type filtration apparatus 6a-6c, by adjusting the return amount of the treated water 9 to the raw | natural water tank 1, gravity is adjusted. It is possible to adjust the change in the filtration rate per one type of filtration device within a certain range. The amount of water returned to the raw water tank 1 of the treated water 9 is preferably adjusted by controlling the output of the water return pump 10 based on the measurement of the flow meter 12 provided in the water return path 11.

  If the amount of raw water 2 in the raw water tank 1 is recovered, gravity filtration is performed by reducing the amount of water returned to the raw water tank 1 of the treated water 9 and / or increasing the number of operating gravity filtration devices 6a to 6c. It becomes possible to adjust the change of the filtration rate per apparatus within a certain range. On the other hand, if the amount of the raw water 2 in the raw water tank 1 is further reduced, the amount of water returned to the raw water tank 1 of the treated water 9 is increased and / or the operation number of the gravity filtration devices 6a to 6c is further reduced. It becomes possible to suppress the change in the filtration rate per gravity filtration device within a certain range.

  If the raw water 2 in the raw water tank 1 becomes excessive, a part of the raw water 2 is discharged from the raw water tank 1 to the treated water tank 8 through the bypass path 13 as an urgent means. Even in such a case, deterioration of the quality of the treated water can be suppressed while securing the amount of water supplied to the subsequent process. After the amount of the raw water 2 is reduced, if the treated water 9 mixed with a part of the raw water 2 is returned to the raw water tank 1, the raw water 2 including the returned water is treated by the gravity filtration devices 6a to 6c and treated. It is possible to bring the water quality of the water 9 close to the original state.

[Example]
Raw water tank volume of about 200 m ³ , treated water tank of about 330 m ³ , gravity filtration device 4 units (upward flow type, filtration area: 18.2 m ² / unit, permissible filtration rate: 13.3-18 m / hour, normal filtration In a filtration treatment facility under conditions of speed: 15 m / hour, filler: granular activated carbon), rated inflow rate of raw water 26050 m ³ / day), three circulation pumps (discharge amount 0.27 to 2.7 m ³ / min), An operation method when the amount of raw water is reduced will be described with reference to FIG.

This filtration facility assumes that raw water is filtered by four gravity filtration devices when the raw water inflow amount is 26050 m ³ / day, which is the rated flow rate. The filtration speed per gravity filtration device is usually 15 m / hour (point A). In addition, the filtration rate per gravity filtration apparatus set 14-15 m / hour to the optimal range, and made 15 m / hour the optimal value.

As the raw water inflow rate decreases, the filtration rate per gravity filtration device also decreases accordingly. When the raw water inflow rate is 24461 m ³ / day and the filtration rate begins to drop below 14 m / hour (point B), if the first circulating pump is started, the increase in the raw water amount will increase the The filtration speed can be maintained at 14 m / hour, and further 15 m / hour, which is the optimum value (point C). If the output of the first circulation pump is gradually increased while the raw water inflow rate decreases from 24461 m ³ / day to 22320 m ³ / day, the filtration speed per gravity filtration unit is set to the optimum value of 15 m / hour. It can be stabilized (between point C and point D).

At point D, the output of the first circulation pump is maximum, so when the raw water inflow rate is reduced to 20573 m ³ / day, the filtration speed per gravity filtration device is 14 m / hour (E point). At this time, when the circulation pump is stopped, the flow of raw water to one gravity filtration device is stopped, and raw water (raw water inflow amount 20573 m ³ / day) is processed by three gravity filtration devices, The filtration speed per gravity filtration device is 15.7 m / hour (point F).

  Since the optimum value of the filtration speed per gravity filtration apparatus is 15 m / hour, in order to reduce the filtration speed, a part of the raw water stored in the raw water tank is bypassed to the treated water tank. In FIG. 2, the shaded area indicated by Q1 represents the amount of raw water to be bypassed. By restricting the flow rate regulating valve at the inlet of each filtration basin and bypassing the excess raw water, the filtration rate per gravity filtration device can be maintained at an optimum value of 15 m / hour (point G).

When the raw water inflow is reduced to 18346 ³ / day during operation of treating raw water with ^three gravity filtration devices, the filtration rate per gravity filtration device is reduced to 14 m / hour (point H). If the output of the first circulation pump is gradually increased while the raw water inflow decreases from 18346 m ³ / day to 15788 m ³ / day, the filtration speed per gravity filtration device is maintained at 15 m / hour. Obtain (between point I and point J).

When the raw water inflow rate decreases from 18346 m ³ / day to 14458 m ³ / day, even if the first circulation pump is operated at the maximum discharge rate, the filtration speed per gravity filtration device decreases to 14 m / hour. (K point). Therefore, by further operating the second circulation pump, it is possible to increase the filtration speed per gravity filtration device to 15 m / hour (L point).

If the output of the second circulation pump is gradually increased while the raw water inflow decreases from 14458 m ³ / day to 13978 m ³ / day, the filtration speed per gravity filtration device is maintained at 15 m / hour. Obtain (between L point and M point).

At the time of point M, the first and second circulation pumps are stopped, and the flow of raw water to the two gravity filtration devices is stopped, and the raw water (raw water inflow amount 13978 m is stopped by two gravity filtration devices. ³ / day), the filtration rate per gravity filtration device is 16 m / hour (point N).

  Therefore, in order to reduce the filtration rate, a part of the raw water stored in the raw water tank is bypassed to the treated water tank. In FIG. 2, the shaded portion indicated by Q2 represents the amount of raw water to be bypassed. By filtration of raw water, the filtration speed per gravity filtration device can be maintained at 15 m / hour.

  If the raw water inflow rate is further reduced, the filtration rate per gravity filter can be kept within a certain range by operating the circulation pump and / or reducing the number of gravity filter devices in the same manner as above. It is possible to adjust within.

  On the other hand, if the raw water inflow volume starts to increase, the output of the circulation pump is reduced, the circulation pump is stopped, or the raw water is passed again to the gravity filtration device that stopped the flow of the raw water. It is possible to adjust the filtration speed per gravity filtration device within a certain range.

For example, if the raw water inflow rate starts to increase at point J, the gravity filtration device 1 is gradually reduced until the raw water inflow rate reaches 18346 m ³ / day (point I) by gradually reducing the output of the first circulation pump. The filtration speed per table can be maintained at 15 m / hour (three gravity filtration devices are operated). If the first circulation pump is stopped when the raw water inflow rate is 18346 m ³ / day, the filtration speed per gravity filtration device decreases by 14 m / hour. However, as the raw water inflow rate increases, the filtration rate per gravity filtration device also increases. When the raw water inflow rate reaches 19656 m ³ / day, the filtration rate per gravity filtration device is 15 m / day. It ’s time.

At this time, if water flow is immediately resumed in the fourth gravity filtration device, the filtration speed per gravity filtration device is reduced to 11 m / hour. Therefore, until the raw water inflow amount is 20573 m ³ / day, the gravity filtration device is configured such that water is passed through three gravity filtration devices, and a part of the raw water stored in the raw water tank is bypassed to the treated water tank. The filtration speed per vehicle can be maintained at 15 m / hour.

At point G, when water is resumed through the fourth gravity filtration device and the first circulation pump is operated at the maximum output, the filtration speed per gravity filtration device is 14 m / hour. Thereafter, if the raw water inflow rate is 22320 m ³ / day or more, the filtration rate per gravity filtration device can be maintained at 14 to 15 m / hour by gradually decreasing the output of the first circulation pump. .

  If the filtration treatment facility of the embodiment does not return the treated water to the raw water tank by the circulation pump, the bypass amount of the raw water represented by Q1 and Q2 in FIG. 2 is greatly increased. In order to prevent deterioration of the quality of treated water due to such raw water bypass, it will be necessary to install a large number of gravity filtration devices to reduce the effect of fluctuations in the number of operating units. This will increase the size of the equipment.

  The operation method of the filtration treatment facility of the present invention can also be applied to an existing filtration treatment facility equipped with a gravity filtration device, and does not cause an increase in treatment cost and filtration equipment. It is also possible to stabilize the quality of the treated water by adjusting the filtration speed of the gravity filtration device within a certain range.

  The operation method of the filtration treatment facility of the present invention is useful in a water treatment facility such as a water purification plant.

1: Raw water tank 2: Raw water (treated water)
3a to 3c: Flow rate adjusting valve 4a to 4c: Flow meter 5a to 5c: Raw water path 6a to 6c: Gravity filtration device 7a to 7c: Treated water path 8: Treated water tank 9: Treated water 10: Circulation pump 11: Return water Route 12: Flow meter 13: Bypass route 21: Raw water intake route 22: Treated water supply route

Claims (4)

Raw water tank,
A plurality of upward flow gravity filtration devices for filtering raw water stored in the raw water tank;
A treated water tank for storing treated water of the plurality of gravity filtration devices;
A method for operating a filtration facility comprising:
The gravity filtration device is a gravity filtration device filled with a particulate filler,
A circulation pump is provided for feeding the treated water stored in the treated water tank to the raw water tank,
When the amount of raw water in the raw water tank decreases, the number of operating gravity filtration devices is reduced and / or a part of the treated water in the treated water tank is sent to the raw water tank by the circulation pump. Keep the filtration rate of the gravity filtration device constant by increasing the amount of water to
Thereafter, when the amount of raw water in the raw water tank increases, the number of operating gravity filtration devices is increased and / or a part of the treated water in the treated water tank is transferred to the raw water tank by the circulation pump. The operation method is characterized by keeping the filtration rate of the gravity filtration device constant by reducing the amount of water to be fed.   The operation method of the filtration treatment facility according to claim 1, wherein the gravity filtration device is an upward flow gravity filtration device.   The method for operating a filtration facility according to claim 1 or 2, wherein the particulate filler is granular or spherical activated carbon, anthracite, ceramic, or sand.   The filtration processing facility according to any one of claims 1 to 3, wherein a plurality of the circulation pumps are provided, and the number of the circulation pumps to be operated and the output thereof are adjusted according to the amount of water supplied to the raw water tank. Driving method.

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