JP2004066061A - Water treatment method and equipment therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water treatment method and equipment using membrane filtration which surely kills pathogenic protozoa contained in physically washed wastewater to prevent the pathogenic protozoa from being redischarged into raw water. <P>SOLUTION: The physically washed wastewater is temporarily held in a sterilization apparatus provided outside the membrane module. Ozone, ultraviolet rays, or the like are used as a means for sterilization. The sterilization is performed by means of an ozone generator, a waste ozone treatment apparatus, or a UV (ultraviolet ray) lamp. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a water treatment method and apparatus using a membrane, and more particularly to a water treatment method and apparatus using a membrane provided with a method for disinfecting pathogenic protozoa contained in physical washing wastewater.
[0002]
[Prior art]
As a method for treating raw water containing pollutants, a water treatment method using membrane filtration is widely used mainly for simple water supply, because of its advantages such as reliability and automatic operation. However, in a water treatment apparatus using membrane filtration, fouling occurs due to long-term operation, and thus, a problem is that filtration performance is reduced. The decrease in membrane filtration performance due to these causes can be recovered by washing the membrane.
[0003]
One of the methods for cleaning a film is physical cleaning. Physical cleaning includes back pressure water washing (backwashing) in which membrane filtered water flows backward, flushing by water flow on the primary side of the membrane, and air scrubbing in which the membrane is vibrated by air. The substance is removed, and in automatic operation, cleaning is performed under predetermined conditions.
[0004]
[Problems to be solved by the invention]
FIG. 3 shows a configuration diagram as a typical example of a conventional membrane filtration device.
In this figure, first, raw water 1 flows into a raw water tank 2 and is supplied to a membrane module 4 by an operation pump 3 to obtain membrane filtered water 5. The membrane filtered water 5 is stored in a fixed amount in a filtered water tank 6, a part of which is used for physical cleaning, and the rest is treated water 7. At this time, since solid impurities and the like contained in the raw water are trapped mainly on the raw water side of the membrane module, the differential pressure on both sides of the membrane increases, so that physical cleaning is performed when a predetermined condition is satisfied. . In this physical cleaning, backwashing using a backwash pump 8 and air scrubbing using an air compressor 9 are performed at predetermined time intervals, and the washing wastewater is drained by a drainage line 10 by flushing in the next step. Here, since the physical washing wastewater is only drained after removing solid impurities and the like captured by the membrane, depending on whether or not there is a wastewater treatment in a post-process and the method of the wastewater treatment, the pathogen contained in the physical washing wastewater is removed. The protozoa may be re-discharged into raw water without inactivating them, which is a major issue.
[0005]
In addition, as the backwash water, a method using sodium hypochlorite-containing water or ozone water is also performed.However, since these methods are not intended to inactivate the pathogenic protozoa, they are used with chemicals. The device is not designed to allow sufficient reaction time between pathogenic protozoa.
An object of the present invention is to provide a method and apparatus for water treatment using membrane filtration in which pathogenic protozoa contained in physical washing wastewater as described above are surely inactivated and re-discharge of pathogenic protozoa into raw water is prevented. Is to provide.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, wastewater after physical washing for restoring membrane filtration performance is sterilized to inactivate pathogenic protozoa captured in the membrane.
At this time, the physical cleaning wastewater is temporarily stored in the sterilization processing means installed outside the membrane module and sterilized, and the sterilization processing means includes ozone, ultraviolet rays, hydrogen peroxide, hot water, A sound wave is used.
[0007]
In addition, equipment for sterilizing wastewater after physical washing for restoring membrane filtration performance will be provided to inactivate pathogenic protozoa trapped in the membrane.
The physical cleaning wastewater is temporarily stored in a sterilization apparatus installed outside the membrane module, and sterilized.
Specifically, the physical cleaning wastewater is temporarily stored in a sterilization treatment device installed outside the membrane module, and at least an ozone generator and a waste ozone treatment device are provided to perform the sterilization treatment with ozone.
[0008]
Further, the physical cleaning wastewater is temporarily stored in a sterilization treatment device installed outside the membrane module, and at least a UV (ultraviolet) lamp is provided to perform the sterilization treatment with ultraviolet rays.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, two embodiments of the present invention will be described with reference to the drawings.
[Example 1]
FIG. 1 shows a configuration diagram of a water treatment apparatus according to Embodiment 1 of the present invention. FIG. 1 shows a membrane filtration device using ozone as a sterilization treatment device.
[0010]
The difference between this figure and the conventional membrane filtration apparatus of FIG. 3 is that an ozone generator 11 for sterilization, a waste ozone treatment device 13, and a cleaning wastewater sterilization device 14 are added.
In this figure, by supplying raw water 1 flowing into a raw water tank 2 to a membrane module 4 by an operation pump 3, membrane filtered water 5 is obtained. The membrane filtered water 5 is stored in a fixed amount in a filtered water tank 6, a part of which is used for physical cleaning, and the rest is treated water 7. Every 30 minutes after the filtration, physical washing of the backwashing using the backwashing pump 8 and the air scrubbing using the air compressor 9 is performed, and the wastewater from the physical washing removes the pathogenic protozoa contained therein. Perform sterilization treatment.
[0011]
In the present invention, in order to carry out this sterilization treatment efficiently, wastewater by physical cleaning is once flowed into the cleaning wastewater sterilization apparatus 14 and stored, and ozone gas 12 is supplied from the ozone generator 11 to the cleaning wastewater sterilization apparatus 14. Then, treatment is performed with ozone of the physical cleaning wastewater.
At this time, the CT value (dissolved ozone concentration in water × retention time of sterilization treatment) in the ozone treatment is selected as a value necessary for sterilization determined by the target water quality and water temperature. From the experimental results of the present inventors, it is preferable that the CT value of ozone required for sterilization be supplied so that the CT value is 6 mg / L · min or more at a water temperature of 20 ° C. Assuming that the holding time is 6 minutes, the ozone gas concentration is determined in advance by experiments so that the dissolved ozone concentration in the washing wastewater stored in the washing wastewater sterilizing apparatus 14 becomes 1 mg / L or more, and supplied. The dissolved ozone concentration and the holding time are not particularly limited, and may be supplied based on the CT value. When the water temperature is low, the CT value is increased (for example, 4 times when the water temperature drops by 10 degrees), and when the water temperature is low, the CT value is decreased (for example, 1/4 times when the water temperature rises by 10 degrees).
[0012]
The structure of the washing and draining sterilizer 14 is not particularly limited as long as it can ozone-treat the liquid, and a reaction tower type using a diffuser or a circulation type using a static mixer can be used.
The unreacted ozone gas after the ozone treatment is treated in the waste ozone treatment equipment 13. The cleaning wastewater subjected to the sterilization treatment is discharged from the drainage line 10 to the outside of the apparatus. Here, the sterilization process may be performed for each filtration, or may be performed for cleaning drainage in several filtrations. Further, the sterilization process is separated from the cycle in the operation of membrane filtration, and it is clear that there is no problem even if the membrane filtration device performs the sterilization process during filtration.
[0013]
As the membrane module used in the present invention, various types of membrane modules such as hollow fiber, spiral, tubular, flat membrane, and immersion are used. Can be used.
[Example 2]
FIG. 2 shows a configuration diagram of a water treatment apparatus according to Embodiment 2 of the present invention. FIG. 2 shows a membrane filtration device using ultraviolet light as a sterilization treatment device.
[0014]
The difference between this figure and the conventional membrane filtration apparatus shown in FIG. 3 is that a washing and drainage sterilizer 14 and a UV (ultraviolet) lamp 15 are added.
In this figure, by supplying raw water 1 flowing into a raw water tank 2 to a membrane module 4 by an operation pump 3, membrane filtered water 5 is obtained. The membrane filtered water 5 is stored in a fixed amount in a filtered water tank 6, a part of which is used for physical cleaning, and the rest is treated water 7. Every 30 minutes after the filtration, physical washing of the backwashing using the backwashing pump 8 and the air scrubbing using the air compressor 9 is performed, and the wastewater from the physical washing removes the pathogenic protozoa contained therein. Perform sterilization treatment.
[0015]
In the present invention, in order to efficiently carry out this sterilization treatment, wastewater by physical cleaning is once flowed into and stored in the cleaning and wastewater sterilizing apparatus 14, and ultraviolet rays are irradiated from the UV lamp 15 to the cleaning and wastewater sterilizing apparatus 14. The treatment is performed with ultraviolet light from the physical cleaning wastewater.
At this time, the IT value (ultraviolet irradiation amount × retention time of sterilization treatment) in the ultraviolet treatment is selected as a value necessary for sterilization that determines the target water quality. From the experimental results of the present inventors, it is preferable that the irradiation is performed so that the IT value of the amount of ultraviolet light required for sterilization basically becomes IT value = 1 mW · sec / cm ² or more. The holding time is not particularly limited, and irradiation may be performed based on the IT value.
[0016]
The sterilized washing wastewater is drained from the drainage line 10 to the outside of the apparatus. Here, the sterilization process may be performed for each filtration, or may be performed for cleaning drainage in several filtrations. Further, the sterilization process is separated from the cycle in the operation of membrane filtration, and it is clear that there is no problem even if the membrane filtration device performs the sterilization process during filtration.
[0017]
The cleaning wastewater subjected to the sterilization treatment is discharged from the drainage line 10 to the outside of the apparatus. Here, the sterilization process may be performed for each filtration, or may be performed for cleaning drainage in several filtrations. Further, the sterilization process is separated from the cycle in the operation of membrane filtration, and it is clear that there is no problem even if the membrane filtration device performs the sterilization process during filtration.
[0018]
The membrane module used in the present invention includes various types of membrane modules, such as hollow fiber, spiral, tubular, flat membrane, and immersion membranes. Can be used.
In addition to the sterilization treatment methods shown in Examples 1 and 2, it is apparent that the same effect can be obtained by the sterilization treatment in the method using hydrogen peroxide, hot water, ultrasonic waves, and the method combining them. is there. In addition, it is preferable that each method be performed after conducting experiments on various raw waters in advance and determining sterilization conditions.
[0019]
【The invention's effect】
As described above, in order to sterilize the physical cleaning wastewater and inactivate the pathogenic protozoa captured by the membrane, the physical cleaning wastewater is temporarily stored in a sterilization processing device installed outside the membrane module, and sterilized. The sterilization process is performed by using an ozone generator, an ultraviolet ray, or the like, and using an ozone generator, a waste ozone treatment device, or a UV (ultraviolet) lamp. As a result, re-discharge of the pathogenic protozoa to the raw water can be prevented.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a membrane-based water treatment apparatus using ozone treatment according to Embodiment 1 of the present invention. FIG. 2 is a configuration diagram of a membrane-based water treatment apparatus using ultraviolet treatment according to Embodiment 2 of the present invention. Configuration diagram of a conventional water treatment device using a membrane [Explanation of symbols]
1: Raw water 2: Raw water tank 3: Operation pump 4: Membrane module 5: Membrane filtration water 6: Filtration water tank 7: Treated water 8: Backwash pump 9: Air compressor 10: Drain line 11: Ozone generator 12: Ozone gas 13: Wastewater ozone treatment device 14: Cleaning wastewater sterilization device 15: UV (ultraviolet) lamp

Claims (8)

In a water treatment method using a membrane, water treatment using a membrane characterized by sterilizing wastewater after physical washing to restore membrane filtration performance and inactivating pathogenic protozoa captured by the membrane. Method. The water treatment method using a membrane according to claim 1, wherein the physical cleaning wastewater is temporarily stored in a sterilization treatment means installed outside the membrane module, and sterilized. . The water treatment method using a membrane according to claim 1 or 2, wherein the sterilization treatment uses ozone and ultraviolet rays in the sterilization treatment. The water treatment method using a membrane according to claim 1 or 2, wherein the sterilization treatment uses hydrogen peroxide, hot water, or ultrasonic waves in the sterilization treatment. A water treatment system using a membrane is equipped with a facility that sterilizes wastewater after physical washing to restore membrane filtration performance, and uses a membrane characterized by inactivating pathogenic protozoa captured in the membrane. Water treatment equipment. The water treatment apparatus using a membrane according to claim 5, wherein the physical cleaning wastewater is temporarily stored in a sterilization apparatus installed outside the membrane module, and sterilized. . The water treatment apparatus using the membrane according to claim 5 or 6, wherein the physical cleaning wastewater is temporarily stored in a sterilization treatment apparatus installed outside the membrane module, and at least an ozone generator and a waste ozone treatment apparatus are provided. A water treatment method using a membrane, wherein the sterilization treatment is performed with ozone. The water treatment apparatus using a membrane according to claim 5 or 6, wherein the physical cleaning wastewater is temporarily stored in a sterilization apparatus installed outside the membrane module, and is provided with at least a UV (ultraviolet) lamp to perform sterilization processing. A water treatment method using a film, which is performed using ultraviolet light.

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