JP2003126840A - Method for inactivating cryptosporidium in water purification plant and water purification facility therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to inactivate cryptosporidium easily, in a short period of time, safely and securely, and carry out dewatering treatment of effluent in a short period of time. SOLUTION: In a water purification plant at least provided with a sedimentation pond 3 and a purified water filtration apparatus 4 in order, at least one of sedimentary effluent in the sedimentation pond 3 and back-washed effluent in the purified water filtration apparatus 4 is concentrated and dewatered, and then, a solid content and discharge thereof are subjected to decompression boiling by a cryptosporidium inactivated facility 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inactivating Cryptosporidium in a water purification plant and a purified water provided with Cryptosporidium inactivation equipment, which can inactivate Cryptosporidium easily, safely and reliably in a short time. It concerns processing equipment.

[0002]

2. Description of the Related Art Cryptosporidium is a parasitic protozoa belonging to the genus Coccidia of the sporelings, and when ingested, it parasitizes and proliferates in the small intestine to cause severe watery diarrhea and abdominal pain. In environmental water, Cryptosporidium has an elliptical shape of 4.5 to 5.4 × 4.2 to 5.0 μm in the case of a small species, and 6.6 to 7.9 × 5.3 to 6 in the case of a large species. .5
Since it exists in the form of oocyst (capsule body) in the shape of μm, even if it is exposed to chlorine, ozone, ultraviolet rays, etc.
It is not inactivated in a short time even if it is heated or pressurized.

[0003] Usually, in water purification facilities, the water to be treated from a water source such as a river is sent to a landing well and from there to a floc formation pond where flocs are formed. Next, precipitation concentration is performed in the sedimentation tank, and the supernatant water is sent to a filtration tank or a purified water filtration apparatus equipped with a membrane filtration apparatus for filtration. Then, the filtered water is sent to the water purification pond and becomes tap water.

In the above-mentioned purified water treatment equipment, wastewater is discharged from each of the settling basin and the purified water filtration device, but as long as the wastewater is returned to the landing well, cryptosporidium usually remains in the system of the purified water equipment. Although it does not mix into tap water, it cannot be said that Cryptosporidium may mix into tap water for some reason.

Therefore, Japanese Patent Laid-Open No. 2000-236857 discloses a method of inactivating Cryptosporidium by pressurizing a liquid containing Cryptosporidium. Hereinafter, this method is referred to as Prior Art 1.

Further, Japanese Patent Laid-Open No. 11-57785 discloses the following method for removing Cryptosporidium in water purification equipment. The wastewater from the settling basin and the effluent for cleaning the membrane filtration device from the membrane filtration device are temporarily collected in the sludge basin. The wastewater is sent to the concentration tank, and the supernatant water is
The concentrated sludge from the drainage pond is sent to a warming device and heated to inactivate (kill) Cryptosporidium. On the other hand, the heated concentrated sludge in the heating device is dehydrated by the dehydrator, and the dehydrated cake is
Discarded outside the water purification plant. Hereinafter, this method will be referred to as "prior art 2".

[0007]

According to the above-mentioned prior art 1, Cryptosporidium can be inactivated without heating, but the pressurizing condition for inactivating Cryptosporidium is 1500 kgf / cm ² or more. The pressurization time is 5 minutes or more, and the pressure is 2000 kgf / cm ² or more, and the pressurization time is 2 minutes or more, which requires ultrahigh pressure. Therefore, the pressure treatment equipment required for this requires high strength, not only equipment cost but also handling ultra-high pressure, which is dangerous and requires qualified personnel for safety equipment and operation.

According to the above-mentioned prior art 2, by heating the concentrated sludge mixed with Cryptosporidium, Cryptosporidium can be inactivated, while
The warmed concentrated sludge is dehydrated to form a dehydrated cake, but since the concentrated sludge is simply heated at normal pressure, it takes a long time to process at 60 ° C. for 30 minutes or more.

Therefore, an object of the present invention is to provide a method for inactivating Cryptosporidium in a water purification plant that can safely and reliably inactivate Cryptosporidium in a short time and a water purification facility equipped with the Cryptosporidium inactivating facility. It is provided.

[0010]

The invention according to claim 1 is
At least in a water treatment plant equipped with a water filtration device,
It is characterized by concentrating and dehydrating the backwash waste water in the above-mentioned purified water filtration device, and then boiling the solid content and the waste liquid by this under reduced pressure.

According to a second aspect of the present invention, in a water purification plant equipped with at least a water purification device, the backwash wastewater in the water purification device is concentrated and dehydrated, and then the solid content and the waste liquid resulting therefrom are heated. However, it is characterized by boiling under reduced pressure.

According to a third aspect of the present invention, in a purified water treatment plant equipped with at least a purified water filtration device, the backwash wastewater in the purified water filtration device is concentrated and dehydrated, and then the solid content and the waste liquid are boiled under reduced pressure. Further, it is characterized by heating.

According to a fourth aspect of the present invention, the water purification plant is provided with a sedimentation basin, and the sedimentation wastewater in the sedimentation pond is concentrated and dehydrated together with the backwash wastewater in the water purification filter. Is to have.

According to a fifth aspect of the present invention, in a purified water treatment facility equipped with at least a purified water filtration device, a concentration / dehydration means for concentrating and dewatering the backwash wastewater in the purification water filtration device, and discharge from the concentration / dehydration means. It is characterized in that it is equipped with a Cryptosporidium inactivation facility having a solid content and a reduced pressure boiling means for boiling the waste liquid under reduced pressure.

According to a sixth aspect of the present invention, the purified water treatment facility includes a settling basin, and the concentrating means concentrates and dewaters the backwash drainage in the purified water filtering device and the settling drainage in the settling basin. It has a special feature.

The invention according to claim 7 is characterized in that the reduced pressure boiling means comprises a heating means.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Next, one embodiment of the method for inactivating Cryptosporidium in a water purification plant of the present invention will be described with reference to the drawings.

FIG. 1 is a flow chart showing a method for inactivating Cryptosporidium in a water purification plant of the present invention, and FIG. 2 is a flow chart showing a method for inactivating Cryptosporidium in a water purification plant without a settling tank. FIG. 3 is a configuration diagram of Cryptosporidium inactivation equipment, and FIG. 4 is a partial cross-sectional view of Cryptosporidium inactivation equipment.

1 to 4, 1 is a landing well, 2 is
Is a flocculation basin, 3 is a sedimentation basin, 4 is a water purification device such as a membrane filtration device, 5 is a water purification basin, and 6 is a partial sectional view of a Cryptosporidium inactivation facility.

As shown in FIG. 4, the Cryptosporidium inactivation facility 6 is composed of a plurality of filter plates 9 in which a plate 7 and a filter cloth 8 are packaged and which are releasably overlapped with each other as concentration / dehydration means. In addition, a chamber 10 into which waste water is press-fitted is formed between the filter plates 9. In addition, the Cryptosporidium inactivation facility 6 is equipped with a reduced pressure boiling means and a heating means.

The raw water of the tap water sent to the landing well 1 is sent to the floc formation pond 2 to form flocs. The raw tap water in which flocs are formed is sent to the settling basin 3, where the solid content is settled. Next, the raw water for tap water on which the solid content has been precipitated is sent to the purified water filtering device 4, filtered, sent to the water purification pond 5, and sent to the destination as tap water. Although the oocysts of Cryptosporidium contained in the raw water of the tap water are filtered by the purified water filtering device 4 and are not mixed in the raw water of the tap water, the oocysts of Cryptosporidium remain in the backwash drainage.

However, Cryptosporidium is completely inactivated as follows.

At least one of the settling wastewater in the settling basin 3 and the backwashing wastewater in the purified water filtration device 4 is uniformly pressed into the chamber 10 formed between the filter plates 9, whereby solid matters in the wastewater are discharged. The solid material layer is formed by being captured on the surface of the filter cloth 8. At this time, most of the Cryptosporidium oocysts are trapped in the solid matter.

On the other hand, the filtrate (drainage) that has passed through the filter cloth 8 is
Drained from the water collection pipe (not shown) to the outside of the chamber 10,
A part of Cryptosporidium oocysts is also mixed in this filtrate. When the inside of the chamber 10 is filled with the solid matter, the press-fitting of the drainage into the chamber 10 is stopped,
As shown in FIG. 3, compressed air is flown into the chamber 10 to further reduce the water content of the dehydrated cake in the chamber 10. At this time, the filtrate discharged from the chamber 10 is sent to the gas-liquid separation tank 11 from the water collection pipe and separated into gas and liquid.

Next, the decompression pump is activated to activate the chamber 1.
The inside of 0 is reduced to a predetermined pressure. Then, hot water is sent from the hot water tank 12 into the chamber 10A outside the filter cloth 8 by the hot water circulation pump 13. This allows chamber 1
The dehydrated cake in 0 is heated via the filter cloth 8. Since the pressure inside the chamber 10 is reduced, the boiling point decreases,
At a temperature below 00 ° C, the dehydrated cake dries easily and the water content is further reduced. At the same time, the water in the cells of Cryptosporidium in the dehydrated cake boiled and the cells were destroyed,
Inactivate in a short time.

The filtrate in the gas-liquid separation tank 11 also boiled under reduced pressure, and Cryptosporidium in the filtrate is completely inactivated in a short time. If a heating means such as warm water heating is provided inside the gas-liquid separation tank 11, Cryptosporidium can be more reliably inactivated.

When the dehydrated cake in the chamber 10 is dried in this way, the filter plates 9 are separated from each other. As a result, the dried dehydrated cake falls from the chamber 10 and is collected.

The settling wastewater in the settling basin 3 and the backwash wastewater in the purified water filtering device 4 are heated by the above heating means before being pressed into the chamber 10, or
By heating after heating under reduced pressure, Cryptosporidium can be more reliably inactivated.

In FIG. 2, there is no settling basin, and instead, an auto strainer 14 is provided between the landing well 1 and the water purification device 4.
The flow diagram of the inactivation method of Cryptosporidium in a water purification plant in the case of providing and the raw water tank 15 is shown.

In this case, the raw water of the tap water from the landing well 1 is sent to the purified water filtering device 4 via the auto strainer 14 and the raw water tank 15. The inactivation treatment of Cryptosporidium in the backwash drainage of the purified water filtration device 4 is the same as in the case of FIG.

[0031]

As described above, according to the present invention, the waste water mixed with Cryptosporidium is concentrated and dehydrated, and the solid content and the waste liquid resulting therefrom are boiled under reduced pressure, whereby Cryptosporidium can be easily obtained. It is possible to safely and surely inactivate in a short time, and moreover, dehydration treatment of waste water can be completed in a short time, which brings useful effects.

[Brief description of drawings]

FIG. 1 is a flow chart showing a method for inactivating Cryptosporidium in a water purification plant of the present invention.

FIG. 2 is a flow chart showing a method for inactivating Cryptosporidium in a water purification plant when there is no sedimentation basin.

FIG. 3 is a configuration diagram of Cryptosporidium inactivation equipment.

FIG. 4 is a partial cross-sectional view of Cryptosporidium inactivation equipment.

[Explanation of symbols]

1: Landing well 2: Flock formation pond 3: Settling pond 4: Water purification device 5: Purification pond 6: Cryptosporidium inactivation facility 7: Plate 8: Filter cloth 9: Filter plate 10: Chamber 11: Gas-liquid separation tank 12: Hot water tank 13: Hot water circulation pump 14: Auto strainer 15: Raw water tank

Claims (7)

[Claims] 1. A water purification plant equipped with at least a purified water filtration device, characterized in that the backwash wastewater in the purified water filtration device is concentrated and dewatered, and then the solid content and drainage resulting therefrom are boiled under reduced pressure. Method for inactivating Cryptosporidium in water purification plants. 2. In a water purification plant equipped with at least a purified water filtration device, the backwash wastewater in the purified water filtration device is concentrated and dehydrated, and then the solid content and the waste liquid thereby are boiled under reduced pressure while heating. A method for inactivating Cryptosporidium in a water purification plant, which is characterized. 3. In a water purification plant equipped with at least a purified water filtration device, the backwash wastewater in the purified water filtration device is concentrated and dehydrated, and then the solid content and the drainage liquid are boiled under reduced pressure and further heated. A method for inactivating Cryptosporidium in a water purification plant, which is characterized in that 4. The water purification plant is provided with a sedimentation basin, and the sedimentation wastewater in the sedimentation pond is concentrated and dehydrated together with the backwash wastewater in the water purification device. 5. The method for inactivating Cryptosporidium in a water purification plant according to any one of 1 to 3. 5. In a purified water treatment facility equipped with at least a purified water filtration device, concentration / dehydration means for concentrating and dehydrating the backwash wastewater in said purification water filtration device, and solid content and drainage discharged from said concentration / dehydration means. A water purification plant facility comprising a Cryptosporidium inactivation facility having a reduced pressure boiling means for boiling under reduced pressure. 6. The purified water treatment facility comprises a settling basin, and the concentrating means concentrates and dewaters the backwash drainage in the purified water filter and the settling drainage in the settling basin. The water purification plant facility according to claim 5. 7. The water purification plant facility according to claim 5, wherein the reduced pressure boiling means comprises a heating means.