JP2010188349A - Medium and membrane filtration-combined filtration facility, and operation method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filtration facility and an operation method therefor with little risk and with extremely excellent water treatment efficiency, the facility achieved by combining filtration technologies of a conventional media filter basin and a membrane filtration apparatus to solve problems of both the technologies and made compact by reducing a installation space, and exactly and flexibly coping with the increase or fluctuation of water to be treated and variation of water quality. <P>SOLUTION: The medium and membrane filtration-combined filtration facility includes a media filter basin M and a membrane filtration apparatus S formed by disposing a plurality of membrane modules 16 in a filtration tank 11 of the media filter basin at a position lower than the water level L of the water to be treated at the filtration time. The water H to be treated fed to the filtration tank 11 is simultaneously filtered in both the media filter basin and membrane filtration apparatus, to simultaneously obtain treated water from both the media filter basin and membrane filtration apparatus. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a filtration facility suitable for various types of water treatment such as water purification in a water purification plant, and more particularly to a combined filtration facility in which a media filtration pond and a membrane filtration device are organically combined and an operation method thereof.

  Conventionally, water treatment in a water purification plant generally employs a so-called media filtration basin (media filter or filtration device) using a particulate filter medium such as sand, anthracite, or granular activated carbon as a filtration layer.

  However, this media filter basin has a constant filtration rate (the amount of treated water is constant), so it is not efficient as a facility to repeatedly operate and stop the media filter pond with respect to fluctuations in the treated water amount. In addition, there is a problem that it cannot cope with an urgent increase in the amount of treated water.

  In recent years, membrane filtration devices have been developed as an alternative to such media filtration ponds, and are becoming popular mainly in small-scale water purification plants. This membrane filtration device is compact and requires only a small installation space. It can also separate suspended substances and minute pathogenic protozoa, and select the type of membrane (MF membrane, UF membrane, NF membrane, etc.) This makes it possible to treat water to be treated with various water qualities. Furthermore, since the membrane module is a unit type, it can be freely adapted according to the treatment scale of the water to be treated, and the construction period is short.

  Although the membrane filtration device has these advantages, it uses a precise membrane, which causes clogging of the membrane module. Therefore, chemical cleaning must be performed several times a year. Therefore, the membrane module needs to be replaced, and there is a disadvantage that the running cost is high in addition to the apparatus cost.

  Moreover, the filtration equipment which uses together this media filtration pond and a membrane filtration apparatus is also proposed (patent document 1 etc.). However, such equipment does not return the backwash wastewater from the media filtration basin to the raw water, but treats it using a membrane filtration device to reduce the burden on the media filtration basin. It is necessary to install a filtration device and its associated device, and the entire equipment becomes large and the installation space is further increased. Moreover, the treatment capacity (purified water volume) of the treated water basically depends on the filtration rate of the media filtration basin and cannot cope with large fluctuations in the supply amount of the treated water. There are problems such as inability to adequately respond to changes in water quality.

Recently, it has become more difficult to secure large-scale investments including water treatment facilities such as water treatment plants, and to operate and maintain these facilities, and on the other hand, it is possible to respond accurately to the increase and fluctuation of treated water such as water purification. At the same time, the water quality standards for treated water are finely limited, and sufficient quality control of treated water is required even for changes in the quality of treated water, and the risks to these must be avoided. .
JP 2003-236558 A

  The present invention is based on such a severe background in water treatment, fusing the filtration technology using conventional media filtration ponds and membrane filtration devices, eliminating the problems of both, and compact equipment that requires less installation space, The purpose of the present invention is to provide a filtration facility having an extremely excellent water treatment efficiency and an operating method with a low risk that can accurately and flexibly cope with an increase, fluctuation and water quality fluctuation of water.

And the feature made into the summary of this invention completed for achieving such an objective is as follows.
(1) A media filtration pond and a membrane filtration device in which a plurality of membrane modules are disposed in a filtration tank of the media filtration pond at a position below the water level of the water to be treated at the time of filtration. The treated water supplied to the filter is simultaneously filtered by both the media filtration basin and the membrane filtration device, and the filtered water is obtained simultaneously from both the media filtration pond and the membrane filtration device. A medium and membrane filtration combined filtration facility characterized in that (Claim 1).
(2) The media and membrane filtration combined filtration facility according to (1), wherein the position of the membrane module of the membrane filtration device is located above the inside of the filtration tank of the media filtration basin (Claim 2).
(3) The media and the membrane according to (1) or (2), wherein the media filtration pond has a galit into which treated water flows, and the membrane module is disposed in a state where the membrane module is accommodated in a groove of the galit. Filtration combined filtration equipment (Claim 3).
(4) The media and membrane filtration combined filtration facility according to (3), wherein a trough branched in a direction perpendicular to the galit is disposed.
(5) In the operation method using the medium and the membrane filtration combined filtration facility described in (1) above, the medium can be used for fluctuations in the supply amount of the treated water, fluctuations in the required purified water amount, or changes in the quality of the treated water. A medium for producing purified water by changing the ratio of filtration and membrane filtration, and a method for operating a membrane filtration combined filtration facility (Claim 5).

  According to the present invention, by providing a filtration facility in which a media filtration pond and a membrane filtration device are combined organically and integrated, the installation space is small and a compact facility form is obtained, and the increase, fluctuation and water quality change of treated water. It is possible to realize and establish a low-cost composite filtration technology that can be accurately and flexibly dealt with, and that is extremely excellent in water treatment efficiency with low risk.

It is a schematic diagram of the whole water purification processing equipment explaining one embodiment of the compound filtration equipment of the present invention. FIG. 2 is a schematic side sectional view of the filtration tank of FIG. 1 for explaining an embodiment of the composite filtration equipment of the present invention. It is a schematic diagram (front view) which shows the basic feature concept of the composite filtration equipment of this invention. It is a front notch perspective view which shows other embodiment of the composite filtration equipment of this invention. It is the front notch perspective view which showed the flow at the time of the composite filtration by other embodiment of the composite filtration equipment of this invention in the said FIG. It is the front notch perspective view which showed the flow at the time of the backwashing of the membrane module of the membrane filtration apparatus by other embodiment of the composite filtration equipment of this invention in FIG. FIG. 5 is a front cutaway perspective view showing a flow during backwashing of a filter medium layer 1 of a media filtration pond according to another embodiment of the composite filtration facility of the present invention in FIG. 4.

  The present invention will be described in detail below based on typical embodiments thereof. In the following, although water purification treatment is mainly described as a treatment target of the water treatment facility according to the present invention, the present invention is not limited to this, and various types including impurities generated in various fields such as industrial water, domestic water, and sewage. It can be applied to the treatment of wastewater.

  FIG. 1 is a schematic diagram of the whole water purification treatment facility for explaining an embodiment of the combined filtration facility of the present invention. Here, reference numeral 1 denotes a landing well that guides the raw water G from a river or the like. The raw water stored in the landing well 1 is supplied to a pretreatment facility A for pretreatment, and is further treated as water H to be treated according to the present invention. It is supplied to the filtration facility B to become purified water.

  First, the raw water G is supplied to the rapid stirring tank 2 of the pretreatment facility A, where a flocculant is added and rapid stirring is performed, and the pollutant in the raw water G is contacted and mixed with the flocculant to form a floc. The raw water G after rapid stirring is supplied to the next slow stirring tank 3, where gentle stirring is performed, and the flocs further aggregate and grow. Next, the raw water G is guided to the settling basin 4, and the grown floc is separated by gravity. In the case of water sources whose raw water quality has deteriorated due to eutrophication or the like, the raw raw water from which flocs have been separated is decomposed and adsorbed by the ozone agitation tank 5 and activated carbon adsorption tank 6 to remove off-flavors, organic substances, etc. H is supplied to the combined filtration equipment B of the present invention.

  This combined filtration facility B has two different filtration means (filtration devices): a media filtration pond (hereinafter sometimes referred to simply as media) M and a membrane filtration device (hereinafter also referred to as membrane filtration device or simply as membrane) S. Are integrated as a facility. The media filtration basin M has a filter medium layer 12 below a filtration tank (hereinafter sometimes abbreviated as a tank) 11 for water to be treated H, and a trough 13 is provided above the filter medium layer 12. A water collecting device 14 is provided at the lower part of the filter medium layer 12 of the tank 11, and purified water J1 is sent from the water collecting device 14 subjected to media filtration to the purified water reservoir 15 through a pipe. Then, an immersion type membrane filtration device S in which a plurality of membrane modules 16 are arranged as a unit at a position below the water level (L) of the water to be treated is installed inside the tank 11 of the media filtration pond M. ing. The membrane module 16 is made of, for example, a hollow fiber or ceramic.

  The membrane module 16 is disposed at the center of the filter medium layer 12 provided separately on both sides of the lower portion of the tank 11 and the trough 13 thereon, as shown in FIG. 2 showing a side cross section of the tank 11 of FIG. In the media filtration basin M, the garrit (groove) 19 having a bowl shape for discharging backwash drainage of the water to be treated H is immersed and disposed. The galit 19 is provided over the entire length of the tank 11, the trough 13 is connected to the left and right of the trough 13, and the treated water H supplied through the inflow trough (described later) enters the galit 19, After being diverted to the left and right through a pair of troughs 13 (two in the figure), they are filtered through the lower filter medium layer 12. The membrane module 16 is provided at a position away from the connecting portion of the garit 19 with the trough 13.

  In the membrane filtration device S, the to-be-treated water H supplied and stored in the tank 11 is suction filtered from each membrane module 16 via a pipe by a pump 17 and sent to the water purification basin 15 as purified water J2. Reference numeral 18 denotes a flow meter, which can be adjusted to an arbitrary membrane filtration flux or an arbitrary flow rate by measuring the flow rate of the purified water J2 and feeding it back to the pump 17. In some cases, it is possible to perform filtration with the flow meter 18 and the flow control valve using the difference in water level between the tank 11 and the water purification tank 15.

  In order to prevent the filtration efficiency from decreasing due to clogging of the filter medium layer 12 of the media filtration pond M and the membrane module 16 of the membrane filtration device S above the media filtration pond M A washing water tank 23 in which the washing water K to be used is stored is installed on the elevated. If an elevated washing tank cannot be installed, a dedicated pump for backwashing the media filtration basin M and the membrane filtration device S is installed in the water purification basin 15. This washing water tank 23 is connected to the positions of * 1 and * 2 of the pipes that send the filtered purified water J1 and J2 to the purified water basin 15 through the pipes. It can be supplied to each of the layer 12 and the membrane module 16 of the membrane filtration device S. Although not shown, these pipes are provided with valves for switching between normal filtration and backwashing. In this example, since the washing water tank 23 is on the elevated, a dedicated pump for backwashing the media filtration basin M and the membrane filtration device S becomes unnecessary, which is advantageous in terms of equipment. 24 is for supplying air to an air bubbling device (not shown) disposed at the bottom of the filter medium layer 12 of the media filtration basin M and the membrane module 16 of the membrane filtration device S in order to enhance the backwashing effect by the washing water. This is a cleaning blower. Since only one cleaning blower 24 can be used for both backwashing, it is advantageous in terms of equipment.

  The basic concept of filtration of the composite filtration equipment B according to the present invention will be described with reference to the schematic diagram (front view) of FIG. 3. Enters the membrane module 16 of the membrane filtration device (membrane filtration device) S installed in the upper part of the tank 11 and is sucked and flows to the right side of the figure. It is discharged out of the tank 11 as J2. At the same time as the membrane filtration, the remaining part of the treated water H flows down in the tank 11 and passes through the filter medium layer 12 of the media filtration pond M from the top to the bottom. Then, after passing through the water collecting device 14, it is discharged out of the tank 11 as purified water J1. The purified water J1 obtained by the membrane filtration and the purified water J2 obtained by the media filtration are collected together (J) in the purified water pond 15 and used for water purification purposes such as tap water.

As described above, in the present invention, both the media filtration and the membrane filtration are performed simultaneously by the composite filtration facility including the media filtration basin M and the membrane filtration device (membrane filtration device) S integrated therein. It is possible to realize a composite filtration process that can be performed. Therefore, by adopting the present invention, media filtration and membrane filtration with different operation modes are actively used together and cooperated, and various water treatments are performed by an extremely efficient process with less risk that maximizes the advantages of each process. Processing can be performed.

That is, according to the present invention, media filtration and membrane filtration can be performed at the same time, so that filtration can be performed at a higher speed compared to filtration by a media filtration pond alone, and the throughput can be adjusted by adjusting the filtration rate (flow rate) of both. By controlling, the ability to cope with an increase or fluctuation in the amount of treated water (or demand for fluctuations in the amount of purified water) is greatly improved. For example, when the rapid filtration of 100 m ² / pond is used as a model for the increase in the supply amount, the conventional media filtration pond has 12,000 to 24,000 m ³ / day / pond, whereas the present invention has 12,000. -48,000m ³ / day / pond can be handled.

  Moreover, it becomes possible not only to change the supply amount, but also to produce purified water having a constant water quality that is required by changing the ratio of the treatment amounts of both of the treated water.

  In addition, according to the present invention, the membrane filtration device can be integrated in the installation space of the media filtration pond, so that the water treatment amount (purified water amount) per installation area can be remarkably improved, and compact equipment can be used. It can be implemented, and the installation area of the entire facility can be reduced. Accordingly, the site can be easily secured and the capital investment can be reduced. In particular, the increase in the supply volume of existing media filtration ponds can be dealt with by simply installing a membrane filtration device in the media filtration pond without the need for additional installation space for expansion. It is a waste.

Furthermore, as compared with the membrane filtration device alone, clogging of the membrane module and its replacement are reduced, stable operation and operation can be continued, and running cost is also reduced.
In addition, according to the present invention, the backwash waste water from the membrane filtration device (membrane module) can be filtered as it is in the media filtration basin, and the membrane filtration recovery rate can be maintained at 100%.
Next, the composite filtration equipment of the present invention will be disclosed in more detail with reference to FIGS. 4 to 7 including a processing method such as backwashing according to another embodiment.

  FIG. 4 is a front cutaway perspective view of the present facility, in which a filter medium layer 12 is provided at the bottom of the tank 11 of the media filtration pond, and a membrane module 16 of a membrane filtration device is provided above the filter medium layer 12. In this embodiment, the four series of membrane modules 16 are arranged in a state of being housed in the groove of the galit 19 disposed in the center in the width direction of the tank 11 and extending in the longitudinal direction thereof. It is below the water level of the water to be treated H supplied to the water, and is immersed in the water. That is, this example is a form in which this galit 19 is utilized as an immersion tank for the membrane module 16. On each side of the galit 19, five troughs 13 communicating with this and branching in a right angle direction are arranged. 20 is an inflow trough provided on the upper side of one side wall of the tank 11 in order to allow the water H to be treated to flow into the galit 19, and 21 is for discharging the purified water media-filtered by the filter medium layer 12 out of the tank 11. Therefore, it is an outflow gutter provided at the bottom of the side wall. Reference numeral 22 denotes a drainage basin installed at the lower part of the other side (opposite side) of the tank 11 in order to drain the drainage of the filter medium layer 12 after backwashing. 17 is a pump used for membrane filtration or the like mounted on the upper wall of the drain 22 outside the tank 11.

FIG. 5 is a front cutaway perspective view showing a flow during normal combined filtration in which membrane filtration and media filtration are simultaneously performed by the filtration facility of the present embodiment, whereby a combined filtration process using the facility is performed. The outline of will be described. The flow of the water to be treated H (and purified water after filtration) is indicated by arrows.

The treated water H pretreated by the pretreatment facility flows into the tank 11 by the inflow tank 20 of the combined filtration facility until the galit 19, trough 13, and the membrane module 16 in the galit 19 are completely immersed. When the tank 11 is filled and reaches the same water level as that of the inflow trough 20, the operation is started by operating the valves and pump activation means of the media filtration pond and the membrane filtration device. The filtration rate by both apparatuses is set or changed in an appropriate range in advance or during its operation according to the supply amount of the water to be treated H or the like. With this operation, the treated water H continuously flowing into the galit 19 is first sucked by the pump 17 into the plurality of membrane modules 16 of the membrane filtration device and subjected to membrane filtration, and the purified water J1 treated thereby is It is discharged out of the tank 11 and sent to the water purification tank 15. In addition, a part of the treated water H that has flowed in passes through the filter medium layer 12 of the media filtration pond and is subjected to media filtration, and the purified water J2 treated thereby flows out to the outflow trough 21 sequentially through the water collecting device 14. In the same manner, it is sent to the water purification pond 15.

Next, the flow at the time of backwashing of this composite filtration equipment will be described with reference to the same front cutaway front view 6 and FIG. FIG. 6 shows a state where the membrane module 16 of the membrane filtration device is cleaned, and FIG. 7 shows a state where the media layer 12 of the media filtration basin is cleaned. The arrows in both figures show the flow of cleaning water (and backwash drainage after cleaning) during backwashing.
Therefore, when the membrane module 16 of the membrane filtration device is washed, the washing water K is removed from the washing water tank 23 provided on the overhead shown in FIG. Supplied to 16 and backwashed. At the same time, bubbling air is sent to the lower part of the membrane module 16 by the cleaning blower 24 shown in FIG. 1, and air bubbles collide with the membrane. Then, the cleaning water supplied to the membrane module 16 accommodated and immersed in the galit 19 passes in the opposite direction to that during filtration and is cleaned by the action of bubbles. The backwash wastewater that has passed through the membrane module 16 and passed through the filter medium layer 12 passes through the filter medium layer 12 and is subjected to media filtration in the same manner as during normal filtration. It is discharged outside and sent to the water purification pond 15.

  In addition, when the filter medium layer 12 of the media filtration basin is backwashed, the supply of the treated water H from the inflow tank 20 is stopped, and the water in the tank 11 is discharged from the discharge tank 22 in advance, and the water level L is changed to the membrane module. It is lowered to a position directly below 16, and the wash water K is supplied from the wash water tank 23 on the elevated line in FIG. Pass through to clean. At the same time, bubbling air is sent to the bottom of the filter medium layer 12 by the cleaning blower 24 of FIG. Then, the washed backwash drainage generated by passing upward through the filter medium layer 12 flows from the upper part of the filter medium layer 12 through the trough 13 toward the drainage basin 22 and is discharged out of the tank 11 from the drainage basin 22. Will be.

  In the case where the membrane module 16 is cleaned using a chemical, the target chemical solution is supplied into the galit 19 by a portable chemical solution transfer pump, and this is satisfied, and the membrane module 16 is immersed in this chemical solution. That is, a cleaning method using the galit 19 as a chemical solution immersion tank may be employed.

  In the description of the embodiment, a hollow fiber membrane is shown as the membrane module 16, but of course the present invention is not limited to this, and other types such as a flat membrane and a tubular membrane may be used. is there. Moreover, when obtaining purified water, MF membrane, UF membrane, etc. are used suitably. Sand, anthracite, granular activated carbon, etc. can be used for the granular filter medium which is a medium.

  A: Pretreatment equipment B: Combined filtration equipment H: Treated water M: Media filtration pond S: Membrane filtration device J1, J2: Clean water K: Wash water 11: Filtration tank 12: Filter media layer 13: Trough 14: Water collection Equipment 15: Water purification tank 16: Membrane module 17: Pump 18: Flow meter 19: Galit 20: Inflow tank 21: Outflow tank 22: Discharge tank 23: Washing water tank 24: Cleaning blower

Claims (5)

  A medium filtration pond, and a membrane filtration device in which a plurality of membrane modules are arranged at a position below the water level of the water to be treated at the time of filtration, and supplied to the filtration tank. The treated water is filtered at the same time by both the media filtration basin and the membrane filtration device, and purified water is obtained at the same time from both the media filtration pond and the membrane filtration device. Media and membrane filtration combined filtration equipment.   The media and membrane filtration combined filtration equipment according to claim 1, wherein the position of the membrane module of the membrane filtration device is located above the inside of the filtration tank of the media filtration pond.   The media and membrane filtration combined filtration facility according to claim 1 or 2, wherein the media filtration pond has a galit into which treated water flows, and the membrane module is disposed in a state where the membrane module is accommodated in a groove of the galit.   The media and membrane filtration combined filtration equipment according to claim 3, wherein a trough branched in a direction perpendicular to the galit is disposed. In the operation method using the media and membrane filtration combined filtration equipment according to claim 1, media filtration and membrane filtration with respect to fluctuations in the supply amount of the treated water, fluctuations in the required purified water amount or changes in the quality of the treated water The method of operating a medium and a membrane filtration combined filtration facility for producing purified water by changing the ratio of the amount of treatment.