JPH11169612A - Water filtration device and removing method of pathogenic microorganism in water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water filtration device for removing and inactivating a pathogenic microorganism by equipping an ultraviolet ray irradiation means in the inside space of a cylindrical filter body composed of a porous inorganic membrane and providing a treating water feed passage for supplying a water to be treated to the inside space of the filter body and a treated water discharged passage for discharging the resultant filtrate. SOLUTION: The water filtration device 1 is constituted so that an ultraviolet ray irradiation means is provided in the inside space of the cylindrical filter body 2 composed of the porous inorganic membrane. And the treating water feed passage 5 for supplying the water to be treated to the inside space of the cylindrical filter body 2 is provided to capture the pathogenic microorganism in the supplied water on the inner peripheral surface of the cylindrical filter body 2. The filtrate removed in the pathogenic microorganism flows-out from the outer peripheral surface of the cylindrical filter body 2 to be discharged from the treated water discharged passage 6. At this time, the pathogenic microorganism captured on the inner peripheral surface of the cylindrical filter body 2 is inactivated by the ultraviolet lamp 3. When the porous inorganic membrane is clogged, the treated filtrate is made to flow-in from the treated water discharge passage 7 to back-wash and discharged from a bask-washing waste water discharge passage 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filtration device used for filtering various kinds of water, and particularly to tap water, various kinds of drinking water,
Water filtration equipment useful for producing aseptic water such as water for vending machines, medical water and pharmaceutical production, and also ultrapure water used in the field of semiconductor devices, etc., and removal of pathogenic microorganisms in water using the device. It is about the method.

[0002]

2. Description of the Related Art Water for drinking must be disinfected for safety and inactivated various pathogenic microorganisms. Generally, bacteria are inactivated by chlorination. Chlorine disinfection is very effective for disinfecting bacteria such as Escherichia coli and general bacteria, and can be sufficiently sterilized with a low concentration of chlorine. However, in order to inactivate chlorine-resistant pathogenic microorganisms such as Cryptosporidium, which has recently attracted attention due to the outbreak of outbreaks, it is necessary to make the chlorine concentration extremely high. Not suitable.

When inactivating chlorine-resistant pathogens such as Cryptosporidium, disinfection with ozone or ultraviolet rays is more effective than chlorine, but it is still very costly. For example, when Cryptosporidium is inactivated by ozone, the CT value (concentration × disinfection time) 1
At about 0 mg / L-min, the removal rate is only 99%. Thereafter, the removal rate further increases due to coagulation sedimentation and sand filtration. In addition, since the size of bacteria and protozoa is relatively large (about 1 μm for bacteria and about 3 to 5 μm for cryptosporidium), if costs are ignored,
Means for membrane treatment such as microfiltration and ultrafiltration can be expected to have a very high removal rate of pathogenic microorganisms.

[0004] On the other hand, there has been proposed a water treatment apparatus capable of greatly reducing the treatment cost as compared with the conventional disinfection method (WO).
96/05141). This water treatment system injects filtered water that has been filtered by a sand filter in advance into a container partitioned by a membrane, irradiates the ultraviolet rays while trapping microorganisms in the water on the membrane surface, and inactivates the trapped microorganisms. Device. Further, the microorganisms trapped and inactivated are washed off from the membrane surface by backwashing at regular intervals, and the inactivation treatment is performed once again in the next identical apparatus. In the case of this water treatment apparatus, since the microorganisms captured on the membrane surface are inactivated, the utilization rate of ultraviolet rays becomes extremely high, and the treatment cost can be reduced.

[0005]

[Problems to be Solved by the Invention] WO96 / 05141
Is very effective, but the use of flat membranes results in a small effective filtration area per unit volume, and the ultraviolet irradiation light on the surface other than the membrane surface cannot be used effectively. There is. Furthermore, since the backwash water finally joins the treated water, the end treated water may be contaminated by microorganisms that could not be completely inactivated by ultraviolet rays.

[0006] The problem to be solved by the present invention is to provide a water filtration device for removing pathogenic microorganisms and inactivating them efficiently and a method for removing pathogenic microorganisms in water.

[0007]

According to a first aspect of the present invention, there is provided a filter unit having an ultraviolet irradiation means provided in an inner space of a cylindrical filter made of a porous inorganic membrane. A treated water supply flow path for supplying treated water to the internal space of the cylindrical filter body,
The present invention relates to a water filtration device having a treated water discharge channel for discharging filtered water obtained from the outer peripheral surface of a cylindrical filter.

According to a second aspect of the present invention, there is provided a water filtration apparatus according to the first aspect, wherein a plurality of the filtration units are arranged in parallel in a container. .

The present invention according to claim 3 for solving the above-mentioned problem is characterized in that the surface of the inner peripheral surface of the cylindrical filter is coated with titanium dioxide.
Alternatively, the present invention relates to a water filtration device according to claim 2.

The present invention according to claim 4 for solving the above-mentioned problem is characterized in that the cylindrical filter is a porous inorganic membrane made of a sintered metal.
A water filtration device according to any one of the above.

According to a fifth aspect of the present invention, there is provided a water filtration apparatus for supplying treated water from a treated water supply passage of a water filtration device according to any one of claims 1 to 4. Then, the pathogenic microorganisms in the water to be treated are captured on the inner surface of the cylindrical filter, and the captured pathogenic microorganisms are inactivated by the ultraviolet irradiation means in the filtration unit, and the filtered water is discharged from the outer peripheral surface of the cylindrical filter. And a method for removing pathogenic microorganisms in water.

According to a sixth aspect of the present invention, there is provided a water filtration apparatus for removing pathogenic microorganisms in water to be treated by using the water filtration apparatus according to any one of the first to fourth aspects. , The filtration of the water to be treated is stopped at regular intervals, the filtered water is supplied from the outer peripheral surface to the inner peripheral surface of the cylindrical filter to backwash, and the pathogenicity trapped on the inner surface of the cylindrical filter is The present invention relates to a method for removing pathogenic microorganisms in water, which is characterized by washing off microorganisms and discharging them out of the system.

According to a seventh aspect of the present invention, there is provided a water filtration apparatus comprising: a plurality of water filtration devices according to any one of the first to fourth aspects; 7. The underwater according to claim 6, wherein the timing of the backwashing is shifted, and the filtered water of another water filtering device during the filtration process is used as the backwashing water of the water filtering device in which the backwashing is required. And a method for removing pathogenic microorganisms.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The water to be treated by the apparatus of the present invention is prepared in advance by a known method such as coagulation sedimentation or filtration in order to prolong the filtration life of a cylindrical filter made of a porous inorganic membrane. Those that are turbid are preferred.

The membrane as the filtering means of the apparatus of the present invention is, for example, a porous inorganic membrane formed in a cylindrical shape having a polygonal shape such as a circular or triangular cross section. However, in view of easy production, excellent strength, and no dead space, a cylindrical shape is particularly preferable. The material of the porous inorganic film is not particularly limited, and examples thereof include a sintered metal sintered with a metal such as a stainless steel powder and a ceramic solidified with alumina particles. The reason that the inorganic film is used is that it can withstand a high flux and that it can withstand ultraviolet irradiation, that is, the film material does not deteriorate due to ultraviolet irradiation. The pore size of the porous inorganic membrane is preferably from 1 to 2 μm. If the pore size is smaller than 1 μm, the filtration resistance increases, and it becomes difficult to obtain a high filtration flux. If it is larger than 2 μm, pathogenic microorganisms such as cryptosporidium may leak.

The apparatus of the present invention supplies water to be treated to the internal space of a cylindrical filter, and captures pathogenic microorganisms on the inner peripheral surface of the cylindrical filter. The captured pathogenic microorganisms are inactivated by ultraviolet rays emitted from ultraviolet irradiation means provided in the internal space of the cylindrical filter. Therefore, since the ultraviolet rays are irradiated to the film surface over 360 degrees, the utilization rate of the ultraviolet rays is twice or more as compared with the case where the conventional flat film is used. In other words, if the UV irradiation intensity per unit film area is the same, the number of UV lamps is half that of the conventional one. When it is intended to inactivate pathogenic microorganisms such as Cryptosporidium by the apparatus of the present invention, it is preferable to use a low-pressure mercury lamp capable of irradiating ultraviolet rays having a wavelength of about 254 nm as an ultraviolet lamp, Is 100 mW · s / cm ^{2 to} 1000 mW ·
Seconds / cm ² may be sufficient.

The water filtration apparatus of the present invention can be used for the purpose of oxidatively decomposing organic substances in the water to be treated, for example, by irradiating ultraviolet rays, in addition to inactivating pathogenic microorganisms as described above. In case of UV lamp 1
It is preferable to use a low-pressure mercury lamp capable of irradiating an ultraviolet ray having a wavelength of about 85 nm. However, the UV lamp is not limited to these, and various wavelengths can be used according to the purpose.

The surface of the inner peripheral surface of the cylindrical filter used in the device of the present invention is coated with titanium dioxide,
The photocatalytic action is preferable because the bactericidal effect or the oxidizing effect by ultraviolet rays is improved.

In the apparatus of the present invention, since the pathogenic microorganisms captured by the irradiation of ultraviolet rays are inactivated, organic substances contained in the water to be treated are simultaneously oxidized to produce by-products, which is undesirable for drinking. There is a possibility that by-products are produced although they are very small. Therefore, it is preferable to treat filtered water obtained from the apparatus of the present invention with activated carbon to adsorb and remove by-products.

The permeation speed of the porous inorganic membrane of the treatment apparatus of the present invention depends on the quality of the water to be treated, the filtration pressure, etc., but is generally preferably 20 to 200 m ³ / m ² / h. The duration of filtration is suitably about 5 to 30 min. If the duration is longer than this, clogging of the membrane is likely to occur, and if the duration of filtration is shorter, the recovery rate of water is reduced, which is not preferable.

Referring to FIG. 1, one embodiment of the water filtration device of the present invention will be described.

In the water filtration device 1 of the present invention, an ultraviolet lamp 3 as an ultraviolet irradiation means is provided in a substantially cylindrical container 4 at substantially the center of the internal space of, for example, a cylindrical tubular filter 2 made of a porous inorganic membrane. It is provided in. A treated water supply flow path 5 for supplying treated water is provided in the internal space of the cylindrical filter 2, and the pathogenic microorganisms in the water are captured on the inner peripheral surface of the cylindrical filter 2, and the pathogenic microorganisms are captured. The filtered water from which the water has been removed flows out from the outer peripheral surface of the cylindrical filter body 2 and is discharged from the treated water discharge channel 6. At this time, the pathogenic microorganisms in the water to be treated and the pathogenic microorganisms trapped on the inner peripheral surface of the cylindrical filter 2 that have flowed into the cylindrical filter 2 are improperly irradiated by the ultraviolet light emitted from the ultraviolet lamp 3. Be activated.

If the filtration is continued for a certain period of time, the porous inorganic membrane is clogged. Therefore, the filtration process is stopped, and the filtered water treated by the water filtration device 1 is caused to flow from the treated water discharge channel 6 to reverse. After washing, the backwash wastewater is discharged from the backwash wastewater discharge channel 7 to the outside of the system. In this example, the backwash drainage discharged at the time of the backwash is discharged from the backwash drain discharge channel 7, but the backwash drain discharge channel 7 is not provided as shown in an embodiment described later. Alternatively, the backwash wastewater may be discharged from the treated water supply flow path 5.

As described above, the water used for backwashing is filtered water which has been treated in advance in the water filtration device 1 and from which pathogenic microorganisms have been removed, and which remains inside the water filtration device 1 when the filtration process is stopped. Since the pathogenic microorganisms in the water to be treated are also inactivated by the irradiation of ultraviolet rays from the ultraviolet lamp 3, the backwash wastewater discharged from the water filtration device 1 by backwashing contains pathogenic microorganisms. Therefore, the backwash wastewater can be discharged out of the system without performing any sterilization treatment.

It is also conceivable to treat the water to be treated containing pathogenic microorganisms by using a water filtration device provided with a filtration unit having no ultraviolet lamp in the internal space of the cylindrical filtration body. Since pathogenic microorganisms having activity trapped on the inner peripheral surface of the cylindrical filter are removed from the membrane surface and mixed into the backwash wastewater, the backwash wastewater must be sterilized (inactivated). Since it cannot be discharged, a new sterilization apparatus for backwash wastewater is required, and the processing steps become complicated.

Referring to FIG. 2, one embodiment of a water treatment method when the water filtration device of the present invention is applied to the removal of pathogenic microorganisms in water will be described.

In FIG. 2, first, the valves 8, 10 are opened, and the valve 9 is closed. The to-be-treated water is supplied to the water filtration device 1 from the to-be-treated water supply flow path 5, and the pathogenic microorganisms are captured on the inner peripheral surface of a cylindrical filter (not shown). The captured pathogenic microorganisms are inactivated by ultraviolet rays emitted from an ultraviolet lamp (not shown) housed inside the filtration unit. The filtered water passes through the treated water discharge channel 6 and accumulates in the treated water storage tank 11. In order to eliminate clogging of the tubular filter 2, it is necessary to perform a backwashing process at regular intervals.
To perform the backwashing process, first, the valves 8 and 10 are closed, the valve 9 is opened, and the filtered water stored in the treated water storage tank 11 is used as backwashing water by the backwashing water pump 12 and the treated water discharge flow path. Supply via 6 The backwash water penetrates from the outer peripheral surface of the cylindrical filter, peels off suspended substances and inactivated pathogenic microorganisms trapped on the inner peripheral surface, and is discharged from the backwash water discharge channel 7. Then, it flows into the backwash drainage tank 13 via the valve 9. As described above, since active pathogenic microorganisms are not contained in the backwash wastewater, the backwash wastewater may be discharged as wastewater as it is, or may be returned to the water to be treated (raw water). .

FIG. 3 shows another embodiment of the method for removing pathogenic microorganisms in water according to the present invention. FIG. 3 is a flow chart of an example of an apparatus for providing two water filtration devices in parallel and eliminating an interruption time of a filtration process by backwashing.

In the apparatus of the present embodiment, the two-line water filtration devices 1 and 1 'are operated at an interval different from each other so that they do not simultaneously enter the backwashing operation. First, at the stage where the filtration process is performed simultaneously for two lines, the valve 8 and the valve 8 'are opened, and the valve 9,
Pump 1 with 9 'and valves 14, 14' closed
5, the water to be treated is supplied to the two series of water filtration devices 1, 1 'through the water supply flow paths 5, 5'. The water to be treated is
The treated water (filtrated water) is supplied to the internal space of the cylindrical filter (not shown), the pathogenic microorganisms are captured on the inner peripheral surface of the cylindrical filter, and the permeated treated water (filtrated water) is treated water discharge channels 6, 6 '. And valve 1
After passing through 0 and 10 ′, the water accumulates in the treated water storage tank 11. When the filtration operation is performed for a certain period of time and, for example, the water filtration device 1 reaches a backwashing time, the backwash operation of the water filtration device 1 is performed while the filtration operation is performed by the water filtration device 1 ′ of another system. First, the valves 9 and 14 are opened, and the valves 10 and 14 'are closed. Then, the backwash pump 12 is operated, and the filtered water in the treated water storage tank 11 is supplied to the water filtration device 1 through the valve 14 and the treated water discharge channel 6 as backwash water.
The pathogenic microorganisms trapped on the inner peripheral surface of the cylindrical filter are washed away by the backwash water and discharged out of the system via the backwash drainage discharge channel 7 and the valve 9.

After the back washing operation of the water filtration device 1 is completed, the filtration process may be continued by the water filtration devices 1 and 1 'again. If the water filtration device 1 'of another system reaches the time of backwashing while performing such a filtration operation, the backwash operation of the water filtration device 1' may be performed in the same manner as described above. The backwashing operation of the water filtration device 1 ′ of another system is the same as the backwashing operation of the water filtration device 1, and thus the description is omitted.

By installing two or more water filtration devices in parallel as in the embodiment shown in FIG. 3, the backwashing operation can be performed while performing the filtration operation continuously, and the processing efficiency is improved. improves.

FIG. 4 shows an example of another embodiment of the water filtration device of the present invention. In FIG. 4, arrows indicate the flow of water.

This embodiment is an example in which a plurality of filtration units each having an ultraviolet lamp 3 provided inside a cylindrical filter body 2 are provided in parallel in a cylindrical container 4, and a large amount of water to be treated is filtered. It is preferably used. When a plurality of filtration units are provided in parallel, both ends of each tubular filter 2 are partitioned by partition plates 15 with the tubular filter 2 of each unit oriented in the axial direction.
15 ', and both ends of each cylindrical filter 2 are communicated with the treated water supply flow path 5 through the treated water chambers 16 formed at both ends of the container 4; 15,
15 ′, a filtered water chamber 17 in which each cylindrical filter body 2 is accommodated.
And the filtered water chamber 17 is connected to the treated water discharge flow path 5.
The treated water is supplied to the inside of the cylindrical filter body 2 through the treated water chamber 16, and the filtered water is collected in the filtered water chamber 17 and discharged from the treated water discharge channel 6. What should I do? Further, in this example, unlike the apparatus shown in FIG. 1, a backwash drain discharge channel is not provided. Therefore, the backwash drain may be discharged from the treated water supply channel 5.

The structure of the filtration device in which a plurality of filtration units are housed in the same container is not limited to that of the embodiment shown in FIG. 5. A structure in which the water to be treated supplied from 5 is introduced into the internal space of each cylindrical filter, and the filtered water obtained outside each cylindrical filter is collected in a filtered water chamber and discharged out of the vessel. Any structure may be used.

FIG. 4 shows an example of a horizontal water filtration apparatus in which a filtration unit is horizontally disposed in a container 4, but a vertical water filtration apparatus in which a filtration unit is vertically disposed in a container. It may be a device.

[0036]

EXAMPLE 1 After adding 10 oocysts of Cryptosporidium per liter to sand filtered water of a water purification plant, the filtration pressure was set at 1.5 kg / cm in a device for removing pathogenic microorganisms as shown in FIG.
^2. Filtration was performed under the conditions of a filtration speed of 20 m ³ / m ² / h. A cylindrical (outer diameter: 15 cm, thickness: 3 mm) porous inorganic membrane (nominal filtration hole diameter: 2 μm) made of a stainless steel sintered metal filter was used as the cylindrical filter.

Inside the cylindrical filter of the water filter used, two low-pressure mercury lamps (ultraviolet lamps) having a main wavelength of 254 nm are installed at substantially the center, and 500 mW · sec / cm per filtration area. Ultraviolet light was irradiated at an ultraviolet intensity of ² . The duration of filtration was set to 6 minutes, and then backwashed for 1 minute. The backwash water amount was 2% of the filtered water amount. Filtration water and backwash wastewater were sampled and Cryptosporidium was measured. Table 1 shows the results. Note that the number of fluorescent light-emitting specimens is the total number of specimens including viable specimens and dead specimens.

[0038]

[Table 1]

As is evident from the results shown in Table 1, the oocysts of Cryptosporidium contained in the water to be treated are captured by the cylindrical filter by the apparatus of the present invention.
It is hardly contained in filtered water. Although the captured oocysts of Cryptosporidium are contained in the backwash wastewater, they are almost completely inactivated by ultraviolet light, and it can be seen that there is no problem if the oocysts are discharged as they are.

[0040]

According to the first, fifth and sixth aspects of the present invention, the porous inorganic membrane can easily remove pathogenic microorganisms such as Cryptosporidium in water. Pathogenic microorganisms captured by ultraviolet irradiation means provided in the internal space can be inactivated efficiently,
Further, since the filtration membrane is a porous inorganic membrane, the membrane is not deteriorated by ultraviolet irradiation.

According to the second aspect of the present invention, by arranging a plurality of filtration units in parallel in a vessel, the filtration membrane area can be increased if the vessels have the same capacity, and the same filtration membrane area can be obtained. In this case, the size of the entire water filtration device can be reduced, which is extremely advantageous when treating a large amount of water.

According to the third aspect of the present invention, since the inner surface of the porous inorganic film is coated with titanium dioxide, the inactivated captured pathogenic microorganisms or the oxidation of organic substances in the water to be treated can be performed more efficiently. Can be.

According to the fourth aspect of the present invention, since the porous inorganic membrane is made of a sintered metal, the membrane strength is improved and the filtration pressure is increased, so that a larger amount of water can be treated in a short time. be able to.

According to the seventh aspect of the present invention, since two or more water filtration devices are installed in parallel, the operation of removing pathogenic microorganisms can be performed continuously, and there is no loss associated with the backwashing operation.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one embodiment of a water filtration device of the present invention.

FIG. 2 is a flowchart showing one embodiment of a water treatment method using the water filtration device of the present invention.

FIG. 3 is a flowchart showing another embodiment of the water treatment method using the water filtration / removal device of the present invention.

FIG. 4 is a schematic sectional view showing another embodiment of the water filtration device of the present invention.

[Explanation of symbols]

1, 1 'water filtration device 2 cylindrical filter body 3 ultraviolet lamp 4 container 5, 5' treated water supply flow path 6, 6 'treated water discharge flow path 7, 7' backwash drain discharge flow path 8, 9, 10, 14, 8 ', 9', 10 ', 14' Valve 11 Treated water storage tank 12, 14 Pump 15 Partition plate 16 Treated water chamber 17 Filtration water chamber

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C02F 1/32 C02F 1/72 101 1/72 101 B01D 29/10 520B 530A 29/38 510C 520A

Claims (7)

[Claims] 1. A filtration device in which a filtration unit provided with an ultraviolet irradiation means is provided in a container in an inner space of a cylindrical filter made of a porous inorganic membrane. A water filtration device comprising: a treated water supply flow path for supplying water; and a treated water discharge flow path for discharging filtered water obtained from an outer peripheral surface of a cylindrical filter. 2. The water filtration device according to claim 1, wherein a plurality of the filtration units are arranged in a container in parallel. 3. The water filtration device according to claim 1, wherein an inner peripheral surface of the cylindrical filter is coated with titanium dioxide. 4. The water filtration device according to claim 1, wherein the cylindrical filter is a porous inorganic membrane made of a sintered metal. 5. The water to be treated is supplied from the treated water supply flow path of the water filtration device according to any one of claims 1 to 4, and the pathogen in the treated water is formed on the inner surface of the cylindrical filter. A method for removing pathogenic microorganisms in water, comprising capturing the pathogenic microorganisms, inactivating the captured pathogenic microorganisms by means of ultraviolet irradiation in a filtration unit, and obtaining filtered water from the outer peripheral surface of the cylindrical filter. . 6. A method for removing the pathogenic microorganisms in the water to be treated using the water filtration device according to any one of claims 1 to 4, and stopping the filtration of the water to be treated at regular intervals, It is characterized by supplying filtered water from the outer peripheral surface to the inner peripheral surface of the cylindrical filter and backwashing, washing off pathogenic microorganisms trapped on the inner surface of the cylindrical filter, and discharging the same out of the system. A method for removing pathogenic microorganisms in water. 7. The water filtration device according to claim 1 is installed in two or more lines in parallel, and the timing of backwashing of each water filtration device is shifted, so that the necessity of backwashing arises. The method for removing pathogenic microorganisms in water according to claim 6, wherein filtered water of another water filtration device being filtered is used as backwashing water of the water filtration device.