JP4598643B2 - Water purification system and water purification method - Google Patents

Description

  The present invention relates to a water purification system and a water purification method for inactivating or removing chlorine-resistant pathogenic microorganisms contained in raw water in water purification.

  Chlorine-resistant pathogenic microorganisms such as Cryptosporidium oocysts are highly resistant to chlorine-based disinfectants used in water purification treatment, and are virtually impossible to disinfect (inactivate) with chlorine-based disinfectants. Therefore, Cryptosporidium oocysts and the like are generally separated and removed by coagulation sedimentation treatment, rapid filtration treatment, slow filtration treatment, ultrafiltration (UF membrane filtration), microfiltration (MF membrane filtration) and the like.

  In recent years, it has been confirmed that ultraviolet rays are effective to inactivate Cryptosporidium oocysts and the like (disappear infectivity). Are known.

  Although UV irradiation is effective for inactivating Cryptosporidium, etc., it has no effect on removing turbid components (turbidity) and metals such as iron and manganese that should not be contained in drinking water, and is harmless. It is not enough to make it. Therefore, for raw water containing such substances, ultraviolet irradiation alone is not sufficient, and a method combined with filtration such as rapid filtration, slow filtration, UF membrane filtration, and MF membrane filtration is employed.

  On the other hand, there is a method of using a membrane filtration device that does not have a bobbin type or pleat type backflow washing device as a filtration device in water purification treatment. Since these membrane filtration devices do not have a backwashing mechanism, they are simple as devices and inexpensive in terms of equipment costs.

JP 2002-1319 A Special table 2002-514504 gazette

  Naturally, it is preferable to combine filtration treatment such as rapid filtration, slow filtration, UF filtration, and MF membrane filtration with ultraviolet irradiation in order to improve safety in terms of hygiene. The construction cost will be several times higher than the case. In addition, when combined with a slow filtration pond, labor is required for maintenance such as sand scraping.

  On the other hand, a membrane filtration device that does not have a backwashing device is inexpensive in terms of equipment costs, but if the suspended solids are captured together with the water flow, the filtration resistance increases and eventually water flow becomes impossible. Therefore, it is necessary to replace the filter medium cartridge, which increases the operating cost.

  The present invention is a water purification treatment system and a water purification treatment method capable of easily inactivating or removing chlorine-resistant pathogenic microorganisms contained in water to be treated in water purification treatment.

The present invention is a water purification system for purifying water to be treated, which is a turbidity measuring means for measuring the turbidity of water to be treated, a chlorine-resistant pathogenic microorganism, and a backflow cleaning device When the turbidity measured by the turbidity measuring means is not less than a predetermined reference value, at least the membrane filtration device is used, and the reference When the value is less than the value, the treated water is purified by using at least the ultraviolet irradiation device.

  Moreover, in the said water purification system, it is preferable to have a 2nd membrane filtration apparatus which has a filtration membrane of a larger pore diameter than the pore diameter of the filtration membrane used for the said membrane filtration apparatus, and does not have a backflow washing apparatus. .

Further, in the above water treatment system, the turbidity measured by the turbidity measuring means, and for at least using the membrane filtration unit in the case of more than a reference value determined in advance, if it is less than the reference value at least the second it is preferable that by use of a membrane filtration apparatus for purifying the water to be treated.

  The water purification system preferably further includes a disinfectant injection unit.

Further, the present invention is a water purification method for purifying water to be treated, which is a turbidity measuring step for measuring the turbidity of water to be treated, and capable of removing chlorine-resistant pathogenic microorganisms and backwashing In the case where the measured turbidity is equal to or higher than a predetermined reference value , including a filtration step of filtering the treated water with a filtration membrane that does not perform, and an ultraviolet irradiation step of irradiating the treated water with ultraviolet rays perform at least the filtration step, if it is less than the reference value for purifying the water to be treated by carrying out at least the ultraviolet irradiation step.

  The water purification treatment method may further include a second filtration step of filtering the water to be treated with a second filtration membrane which is a filtration membrane having a pore size larger than the pore size of the filtration membrane and does not perform backwashing. preferable.

Further, in the water treatment method, turbidity was the measured, have lines at least the filtration step in the case of more than a reference value determined in advance, if it is less than the reference value by at least the second filtration process line Ukoto It is preferable to purify the treated water.

  The water purification method preferably further includes a disinfectant injection step.

  According to the present invention, in water purification treatment, a water purification system for inactivating or removing chlorine-resistant pathogenic microorganisms contained in water to be treated, a turbidity measuring device, a membrane filtration device having no backwashing device, and an ultraviolet irradiation device By comprising, equipment and operating expenses can be reduced.

  Hereinafter, embodiments of the present invention will be described.

  Some water purification plants that use water from shallow wells and underground water, etc., supply water as purified water only by chlorine disinfection because the quality of the raw water is very good. In most cases, it is possible to ensure a water quality that has no problem as purified water. However, when there is a risk that a chlorine-resistant protozoan Cryptosporidium or the like is mixed into the raw water, it cannot be said to be a safe water purification system.

  Therefore, in the present embodiment, the water to be treated that may contain pathogenic microorganisms such as Cryptosporidium and Giardia is filtered by a membrane filtration device that does not have a backwashing device, sterilized by ultraviolet irradiation, or by ultraviolet irradiation. The treatment was performed by a sterilization treatment and a filtration treatment by a membrane filtration device having no backflow cleaning device. Furthermore, a means for measuring the turbidity of the water to be treated is provided, the turbidity of the water to be treated before passing through the membrane filtration or ultraviolet irradiation device is measured, and a method for treating the water to be treated is determined based on the measurement result. I decided to decide. Moreover, you may perform the disinfection process by addition of chlorine-type disinfectants, such as sodium hypochlorite and liquefied chlorine, as needed.

  An example of the water purification system according to the embodiment of the present invention is shown in FIG. The water purification system 1 according to this embodiment includes a first turbidity measuring device 10, a second turbidity measuring device 12, a membrane filtration device 14, an ultraviolet irradiation device 16, and a mixing tank 18 that are turbidity measuring means. A disinfectant tank 20 and a disinfectant pump 22 as disinfectant injection means, a stirrer 24, a raw water pump 26, a disinfecting water pump 28, an inlet valve 30, an outlet valve 32, and a bypass valve 34. Prepare.

  One end of the raw water inflow pipe 36 is connected to the mixing tank 18, and the other end is connected to the raw water tank or the like via the raw water pump 26. Note that the raw water pump 26 is not necessary when the natural water can flow in. The first turbidity measuring device 10 is connected in the middle of the raw water inflow pipe 36. A disinfectant tank 20 is connected to the upper part of the mixing tank 18 via a disinfectant pump 22. The mixing tank 18 is provided with a stirrer 24. The lower part of the mixing tank 18 is connected to the lower part of the membrane filtration device 14 through the disinfecting water pump 28 and the inlet valve 30 by the inlet pipe 38. The upper part of the membrane filtration device 14 is connected to the inlet of the ultraviolet irradiation device 16 via an outlet valve 32 by an outlet pipe 40, and the outlet of the ultraviolet irradiation device 16 is connected to a treated water tank or the like by a treated water pipe 42. The second turbidity measuring device 12 is connected in the middle of the treated water pipe 42. The inlet pipe 38 and the outlet pipe 40 are connected via a bypass valve 34 by a bypass pipe 44.

  Next, the operation of the water purification system 1 and the water purification method according to the present embodiment will be described. Raw water (treated water) such as shallow wells and underground water is pumped up by the raw water pump 26 and sent to the mixing tank 18. Before being sent to the mixing tank 18, the turbidity of the raw water is measured by the first turbidity measuring device 10 connected to the raw water inflow pipe 36 (turbidity measuring step).

  Examples of the first turbidity measuring device 10 include means for continuously measuring the turbidity or the number of fine particles of raw water, that is, a turbidimeter or a fine particle meter (a measuring device that counts the number of particles and calculates turbidity). . The turbidity measuring means is preferably an apparatus capable of measuring turbidity with an accuracy of 0.001 degree.

  Next, the disinfectant is injected from the disinfectant tank 20 into the raw water in the mixing tank 18 by the disinfectant pump 22 and is agitated by the agitator 24 to oxidize metals, decompose organic substances, sterilize microorganisms, and the like. (Disinfectant injection process). Here, the disinfectant is added from the disinfectant tank 20 to the water to be treated in the mixing tank 18 by the disinfectant pump 22, but the mixing tank 18 is not provided, and line injection may be performed.

  As the disinfectant, chlorine-based disinfectants such as sodium hypochlorite, liquefied chlorine, chloramine, and chlorine dioxide can be used. Sodium hypochlorite and liquefied chlorine are preferably used, and hypochlorous acid. More preferably, sodium is used. The chlorine injection rate in the disinfectant injection process using sodium hypochlorite or the like can be adjusted so that the residual chlorine concentration is 0.1 mg / L to 1.0 mg / L at the outlet of the ultraviolet irradiation device 16. preferable.

  Next, as the sterilized disinfecting water, at least one of the membrane filtration device 14 and the ultraviolet irradiation device 16 is selected based on the turbidity measured by the first turbidity measuring device 10 in the turbidity treatment step, and raw water. Purification is performed. Here, it is preferable to use at least the membrane filtration device 14 when the measured turbidity is equal to or higher than a predetermined reference value, and to use at least the ultraviolet irradiation device 16 when the measured turbidity is less than the reference value. For example, when the measured turbidity is equal to or higher than a predetermined reference value, the membrane filtration device 14 may be used, and when the measured turbidity is lower than the reference value, the ultraviolet irradiation device 16 may be used. Further, when the measured turbidity is equal to or higher than a predetermined reference value, the membrane filtration device 14 and the ultraviolet irradiation device 16 may be used, and when the measured turbidity is less than the reference value, the ultraviolet irradiation device 16 may be used. Switching of the processing apparatus based on the turbidity of the raw water can be automatically performed.

  The turbidity of the raw water is usually from 0.010 to 0.020 degrees, and in the case of heavy rain, it is 0.030 to 0.070 degrees. When the raw water turbidity is very clear, it is considered that there are almost no chlorine-resistant pathogenic microorganisms such as Cryptosporidium oocysts judging from the turbidity. If the turbidity reference value to be determined in advance is an arbitrary value set within a range of less than 0.1 degree, for example, 0.050 degree, and the raw water turbidity is 0.050 degree or more, the membrane filtration device 14 is used, When the raw water turbidity is less than 0.050 degree, the ultraviolet irradiation device 16 may be used. If this turbidity reference value is 0.040 degrees, more reliable processing can be performed.

  Moreover, when the 2nd reference value higher than the said reference value is set and the turbidity of raw | natural water becomes more than a 2nd reference value, there exists a possibility that a harmful | toxic soluble component will be contained in raw | natural water. Therefore, water intake may be stopped.

  When it is determined that it is appropriate to perform membrane filtration based on the turbidity of the raw water, the inlet valve 30 is opened, the bypass valve 34 is closed, and the disinfecting water is supplied from the mixing tank 18 to the inlet pipe by the disinfecting water pump 28. It is sent to the membrane filtration apparatus 14 through 38, and membrane filtration is performed (filtration process). In the present embodiment, a membrane filtration device that does not have a backflow cleaning device is used as the membrane filtration device 14. Examples of the membrane filtration device that does not have the backflow cleaning device include a cartridge filter and the like, and examples thereof include a thread winding type, a pleat type, and a tubular type. The thread winding type is preferable from the viewpoint of uniformity of the hole diameter. Since these membrane filtration devices do not have a backwashing mechanism, they are simple as devices and inexpensive in terms of equipment costs.

  The pore size of the filter (filtration membrane) used in the membrane filtration device 14 is not particularly limited as long as it can remove chlorine-resistant pathogenic microorganisms such as Cryptosporidium oocysts. The pore size of the filter should be large to reduce filtration resistance, but small to ensure capture of substances that need to be removed, especially chlorine-resistant pathogenic microorganisms such as Cryptosporidium oocysts. Is good. From both points of view, a pore size slightly smaller than the size of the smallest material to be removed is optimal. Since the size of Cryptosporidium oocysts and Giardia cysts is usually 4.2 μm or more, the pore size of the filter is preferably 4.0 μm or less, and more preferably 3.0 μm or less for safety reasons. .

  Here, in this specification, it is assumed that the pore size of the filter is 4.0 μm when particles of 4.0 μm ± 0.2 μm made of polystyrene can be blocked by 99.999% or more.

  Depending on the particle size and concentration of the suspended solids in the raw water and the pore size of the filter, the cartridge filter increases the filtration resistance as water continues and reaches a certain filtration resistance, usually around 100 kPa. Then, since the energy efficiency of filtration falls, the cartridge which is a filter medium is replaced | exchanged. Of course, the lower the cartridge replacement frequency, the lower the operating cost for water purification.

  When it is determined that it is appropriate to perform the ultraviolet irradiation treatment based on the turbidity of the raw water, the inlet valve 30 is closed, the bypass valve 34 is opened, and the disinfecting water is bypassed by the disinfecting water pump 28 from the mixing tank 18. 44 is sent to the ultraviolet irradiation device 16 and an ultraviolet irradiation process is performed (ultraviolet irradiation process). In the ultraviolet irradiation step, the disinfecting water is irradiated with ultraviolet rays, and chlorine-resistant pathogenic microorganisms such as Cryptosporidium oocysts can be inactivated (infectivity is lost). Judging from the raw water turbidity, Cryptosporidium oocysts, etc. are considered to be almost non-existent. It is preferable because safety during use is ensured.

The irradiation amount of the ultraviolet rays irradiated by the ultraviolet irradiation device 16 is not particularly limited as long as it can inactivate chlorine-resistant pathogenic microorganisms such as Cryptosporidium oocysts, but is 10 mJ / cm ^{2 to} 100 mJ / cm ^2. it is preferably in the range ^of, and more preferably in the range of ^{20mJ / cm 2 ~40mJ / cm 2} . If the ultraviolet irradiation dose is less than 10 mJ / cm ² , the chlorine-resistant pathogenic microorganisms may not be sufficiently inactivated. If the irradiation dose exceeds 100 mJ / cm ² , the chlorine-resistant pathogenic microorganisms are not effective. The amount is sufficient for activation.

  The wavelength of ultraviolet rays to be irradiated includes a wavelength of 253.7 nm known as a sterilization line, and examples of ultraviolet lamps include low-pressure mercury lamps, low-pressure high-power mercury lamps, medium-pressure mercury lamps, amalgam lamps, and xenon. A lamp or the like can be used.

  When it is determined that it is appropriate to perform the membrane filtration process and the ultraviolet irradiation process based on the turbidity of the raw water, the inlet valve 30 is opened, the bypass valve 34 is closed, and the disinfecting water is pumped from the mixing tank 18 to the disinfecting water pump. 28, it is sent to the membrane filtration device 14 through the inlet pipe 38 and subjected to membrane filtration (filtration process), and then the filtrate is sent to the ultraviolet irradiation device 16 through the outlet pipe 40 via the outlet valve 32. Then, an ultraviolet irradiation process is performed (ultraviolet irradiation process).

  The treated water that has been subjected to at least one of the membrane filtration process and the ultraviolet irradiation process is discharged to the treated water tank or the like through the treated water pipe 42. In addition, before discharge | release to a treated water tank etc., the turbidity of treated water may be measured for the confirmation by the 2nd turbidity measuring apparatus 12 connected to the treated water piping 42. Moreover, you may share the 1st turbidity measuring apparatus 10 instead of the 2nd turbidity measuring apparatus 12 at the time of confirmation of treated water. In this case, a pipe connected from the treated water pipe 42 to the first turbidity measuring device 10 may be installed. In addition, what is necessary is just to pass through an ultraviolet irradiation device, without irradiating an ultraviolet-ray, when omitting the ultraviolet irradiation process after a filtration process.

  The order of the disinfectant injection means, the membrane filtration device 14, and the ultraviolet irradiation device 16 may be in any order. However, in consideration of protection of the photoelectric tube of the ultraviolet irradiation device 16, etc., the ultraviolet irradiation device 16 is installed after the membrane filtration device 14. It is preferable to do.

  Moreover, in this embodiment, the membrane filtration device that does not have the backwashing device is composed of at least two series of membrane filtration devices having filtration membranes with different pore sizes, and based on the turbidity of the raw water, the two or more series You may switch and use a membrane filtration apparatus.

  An example of the water purification system according to another embodiment of the present invention is shown in FIG. The water purification system 3 according to the present embodiment includes a first turbidity measuring device 10, a second turbidity measuring device 12, a first membrane filtration device 14a, and a second membrane filtration device 14b, which are turbidity measuring means. The ultraviolet irradiation device 16, the mixing tank 18, the disinfectant tank 20 and the disinfectant pump 22, which are disinfectant injection means, the agitator 24, the raw water pump 26, the disinfecting water pump 28, and the first inlet valve 30a. And a second inlet valve 30b, an outlet valve 32, and a bypass valve 34.

  In the water purification system 3, the lower part of the mixing tank 18 is connected to the lower part of the first membrane filtration device 14a via the disinfecting water pump 28 and the first inlet valve 30a by the inlet pipe 38 and the first inlet pipe 38a, and also to the inlet pipe 38. The second inlet pipe 38b is connected to the lower part of the second membrane filtration device 14b through the disinfecting water pump 28 and the second inlet valve 30b. The second membrane filtration device 14b has a filtration membrane having a larger pore size than the first membrane filtration device 14a. Upper portions of the first membrane filtration device 14 a and the second membrane filtration device 14 b are connected to an inlet of the ultraviolet irradiation device 16 through an outlet valve 40 by an outlet pipe 40. The inlet pipe 38 and the outlet pipe 40 are connected via a bypass valve 34 by a bypass pipe 44.

  Next, the operation of the water purification system 3 and the water purification method according to this embodiment will be described. Raw water (treated water) is pumped up by the raw water pump 26 and sent to the mixing tank 18. Before being sent to the mixing tank 18, the turbidity of the raw water is measured by the first turbidity measuring device 10 connected to the raw water inflow pipe 36 (turbidity measuring step).

  Next, the disinfectant is injected from the disinfectant tank 20 into the raw water in the mixing tank 18 by the disinfectant pump 22 and is agitated by the agitator 24 to oxidize metals, decompose organic substances, sterilize microorganisms, and the like. (Disinfectant injection process).

  Next, the disinfected disinfectant water is based on the turbidity measured by the first turbidity measuring device 10 in the turbidity treatment step, and the first membrane filtration device 14a, the second membrane filtration device 14b, and the ultraviolet irradiation device 16 are used. At least one of them is selected to purify the raw water. Here, when the measured turbidity is not less than a predetermined reference value, it is preferable to use at least the first membrane filtration device 14a, and when it is less than the reference value, it is preferable to use at least the second membrane filtration device 14b. . For example, when the measured turbidity is equal to or higher than a predetermined reference value, the first membrane filtration device 14a and the ultraviolet irradiation device 16 are used. When the measured turbidity is less than the reference value, the second membrane filtration device 14b and the ultraviolet irradiation device are used. 16 may be used. Switching of the processing apparatus based on the turbidity of the raw water can be automatically performed.

  When the raw water turbidity is very clear, it is considered that there are almost no chlorine-resistant pathogenic microorganisms such as Cryptosporidium oocysts judging from the turbidity. For example, when the turbidity reference value determined in advance is 0.050 degree and the raw water turbidity is 0.050 degree or more, the first membrane filtration device 14a and the ultraviolet irradiation device 16 are used, and the raw water turbidity is 0.050. In the case of less than the degree, the second membrane filtration device 14b and the ultraviolet irradiation device 16 may be used. If this turbidity reference value is 0.040 degrees, more reliable processing can be performed.

  When it is determined that it is appropriate to perform the membrane filtration treatment by the first membrane filtration device 14a based on the turbidity of the raw water, the first inlet valve 30a is opened and the second inlet valve 30b and the bypass valve 34 are closed. The disinfecting water is sent from the mixing tank 18 by the disinfecting water pump 28 through the first inlet pipe 38a to the first membrane filtration device 14a and subjected to membrane filtration (first filtration step).

  When it is determined that it is appropriate to perform the membrane filtration process by the second membrane filtration device 14b based on the turbidity of the raw water, the second inlet valve 30b is opened and the first inlet valve 30a and the bypass valve 34 are closed. The disinfecting water is sent from the mixing tank 18 by the disinfecting water pump 28 through the second inlet pipe 38b to the second membrane filtration device 14b and subjected to membrane filtration (second filtration step).

  The pore size of the filter (filtration membrane) used in the first membrane filtration device 14a is not particularly limited as long as it can remove chlorine-resistant pathogenic microorganisms such as Cryptosporidium oocysts. The pore size of the filter is optimum to be slightly smaller than the minimum size of the substance to be removed, from the viewpoints of reducing filtration resistance and reliably removing chlorine-resistant pathogenic microorganisms. Since the size of Cryptosporidium oocysts and Giardia cysts is usually 4.2 μm or more, the pore size of the filter used in the first membrane filtration device 14a is preferably 4.0 μm or less. More preferably, it is 3.0 μm or less.

  On the other hand, the pore size of the filter (filtration membrane) used in the second membrane filtration device 14b is not particularly limited as long as it is larger than the pore size of the first membrane filtration device 14a, but may be in the range of 5 μm to 20 μm. Preferably, it is in the range of 7 μm to 10 μm. If it is less than 5 μm, clogging is likely to occur, and if it exceeds 20 μm, the effect of removing trace amounts of iron, manganese, etc. may be reduced.

  By the way, when evaluated by turbidity, when the clear clarified raw water having a turbidity of, for example, less than 0.050 degree is filtered using the first membrane filtration device 14a, for example, when the pore diameter is 4.0 μm A small amount of iron, manganese, and the like gradually adhere, and the filtration resistance increases due to substances other than the 4.0 μm or more material to be removed. Therefore, when the raw water turbidity is very clear from the viewpoint of raw water turbidity, for example, the second membrane filtration device 14b having a filter with a pore diameter of 10 μm is used for filtration. When the pore diameter is 5.0 μm or more, it is difficult to remove 100% of cryptosporidium of about 4 μm. However, even if it is considered that there is almost no Cryptosporidium oocyst etc. judging from the raw water turbidity, it is treated as, for example, drinking water by performing ultraviolet treatment on such clear raw water. This is preferable because safety is ensured when water is used.

  The filtered water that has passed through the first membrane filtration device 14a or the second membrane filtration device 14b is sent to the ultraviolet irradiation device 16 through the outlet pipe 40 through the outlet valve 32 and subjected to ultraviolet irradiation treatment (ultraviolet irradiation). Process). In addition, you may process by the ultraviolet irradiation device 16, after processing using both the 1st membrane filtration apparatus 14a and the 2nd membrane filtration apparatus 14b.

  When it is determined that it is appropriate to perform the ultraviolet irradiation treatment based on the turbidity of the raw water, the first inlet valve 30a and the second inlet valve 30b are closed, the bypass valve 34 is opened, and the disinfecting water is mixed. The tank 18 may be sent to the ultraviolet irradiation device 16 through the bypass pipe 44 by the disinfecting water pump 28, and an ultraviolet irradiation process may be performed (ultraviolet irradiation process).

  The treated water that has been subjected to at least one of the membrane filtration process and the ultraviolet irradiation process is discharged to the treated water tank or the like through the treated water pipe 42. In addition, before discharge | release to a treated water tank etc., the turbidity of treated water may be measured for the confirmation by the 2nd turbidity measuring apparatus 12 connected to the treated water piping 42.

  As in this embodiment, by using together the second membrane filtration device 14b having a filtration membrane having a larger pore diameter than the first membrane filtration device 14a, it is possible to prevent the scale from adhering to the protective tube of the ultraviolet lamp of the ultraviolet irradiation device 16. Although it seems that there are few occurrences, if pebbles, bolts, nuts, etc. are mixed in the raw water, it is possible to prevent damage to the protection tube of the ultraviolet lamp. In addition, depending on the structure of the filter, it is possible to capture particles of less than 10 μm to some extent, so that an effect of improving safety against Cryptosporidium can be expected.

  The water purification system and the water purification method according to this embodiment are used in various treatment processes such as a water treatment facility, an industrial wastewater treatment facility, and an industrial water treatment facility. It can be used for treatment of water, coagulated sediment supernatant water, various process intermediate waters, various recovered waters, various waste waters and the like.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

Example 1
Using the purified water treatment system shown in FIG. 2, raw water was treated under the following conditions.

<Processing conditions>
-Raw water is shallow well water-Raw water turbidity is usually 0.0010 to 0.020 degrees, in case of heavy rain, etc. 0.030 to 0.070 degrees-When raw water turbidity is 0.040 degrees or less, it is passed through a cartridge filter with a pore diameter of 7 μm When water / raw water turbidity is 0.041 degrees or more, water is passed through a cartridge filter with a pore diameter of 3 μm (1) Micropore PFR-SL-070 (pore diameter 10 μm) T type (length 750 mm) × 50, made of polypropylene Replace with cartridge pressure (2) Micropore PFR-SL-030 (pore size 3 μm) T-type (length 750 mm) x 60 polypropylene, Maximum working pressure 500 kPa, filtration resistance 80 kPa Exchange / maximum treated water volume 2400m ³ / day = 100m ³ / hr
・ Ultraviolet irradiation device (ADX-16 type, manufactured by Chiyoda Corporation) Low-pressure ultraviolet lamp, rated 1.83 kW (16 lamps)
・ Maximum UV irradiation 50mJ / cm ²
-Sodium hypochlorite injecting device Injected so that the residual chlorine concentration is 0.8 mg / L at the UV irradiation device outlet

  Raw water (treated water) is passed through a water purification system equipped with a chlorine-based disinfectant injection device, a membrane filtration device (cartridge filter) that does not have a back-flushing device, and an ultraviolet irradiation device, and chlorine disinfection, membrane filtration, and UV sterilization Processed. First, the raw water pumped up by the raw water pump 26 is sent to the mixing tank 18 and mixed with sodium hypochlorite injected by the disinfectant pump 22 to oxidize metals, decompose organic substances, and sterilize microorganisms. . The chlorine injection rate at this time was adjusted to 0.8 mg / L at the outlet of the ultraviolet irradiation device 16.

  Next, about the disinfection water, the membrane filtration process was performed with the membrane filtration apparatus which does not have a backflow washing | cleaning apparatus. Membrane filtration devices that do not have a backwashing device are divided into two systems, one of which uses a filter with a pore diameter of 3 μm (the first membrane filtration apparatus 14a) and the other system (the second membrane filtration apparatus 14b) uses a filter with a pore diameter of 7 μm. did.

  The turbidity of the raw water was measured using a precision turbidimeter (DMT-5S type, manufactured by Microtech Co., Ltd.) which is the first turbidity measuring device 10 in a continuous water flow state. Based on the measurement result of the turbidity of raw water, a series of membrane filtration devices that do not have a backwash device for passing disinfecting water is determined. Specifically, if the turbidity value measured by the turbidimeter is 0.040 degrees or less, the disinfecting water is passed through the second membrane filtration device 14b having a pore diameter of 7 μm and becomes 0.041 degrees or more. In this case, water was passed through the first membrane filtration device 14a having a pore diameter of 3 μm. These cartridge filters having a pore size of 3 μm and 7 μm were automatically switched according to the raw water turbidity measured by a precision turbidimeter. In this example, until the measured value of the precision turbidimeter is 0.040 degrees, the raw water can be judged to be very clear, so the water is passed through a filter having a pore diameter of 7 μm, and the raw water turbidity is 0.041 to 0.100 degrees. Until then, the water was passed through a 3 μm filter, and when the raw water turbidity became 2.000 degrees or more, intake of water was stopped because there is a possibility that harmful soluble components may be included. The filtered water after passing through any of the membrane filtration devices was sterilized by the ultraviolet irradiation device 16 to obtain purified water.

(Comparative Example 1)
3 using the conventional water purification system 5 which is a combination of the membrane filtration device 46 having the backwashing equipment (backwash pump 48) and the ultraviolet irradiation device 16 shown in FIG. Raw water was treated using a hollow fiber membrane filter (pore diameter 3 μm). Table 1 shows a comparison of equipment costs (flows of FIGS. 1 and 3), and Table 2 shows a comparison of operating costs (flows of FIGS. 1 and 3).

  As can be seen from Tables 1 and 2, in the case of the water purification system of Comparative Example 1, the replacement cost of the filter is higher than that of the cartridge filter, and power consumption by backwashing is required. Compared with this, in the case of the water purification system of Example 1, the water purification system for inactivating or removing chlorine-resistant pathogenic microorganisms such as Cryptosporidium in the water to be treated is a membrane filtration that does not have a backwashing device. By constructing with a device, an ultraviolet irradiation device, and a turbidity measuring device, equipment and operating costs could be reduced.

It is a figure showing a schematic structure of an example of a water purification processing system concerning an embodiment of the present invention. It is a figure which shows schematic structure of the other example of the water purification system which concerns on embodiment of this invention. It is a figure which shows schematic structure of the water purification system used by the comparative example of this invention.

Explanation of symbols

1, 3, 5 Water purification system, 10 1st turbidity measuring device, 12 2nd turbidity measuring device, 14 Membrane filtration device, 14a 1st membrane filtration device, 14b 2nd membrane filtration device, 16 UV irradiation device, 18 Mixing tank, 20 Disinfectant tank, 22 Disinfectant pump, 24 Stirrer, 26 Raw water pump, 28 Disinfecting water pump, 30 Inlet valve, 30a First inlet valve, 30b Second inlet valve, 32 Outlet valve, 34 Bypass valve, 36 raw water inflow pipe, 38 inlet pipe, 38a first inlet pipe, 38b second inlet pipe, 40 outlet pipe, 42 treated water pipe, 44 bypass pipe, 46 backwash filter, 48 backwash pump.

Claims (8)

A water purification system for purifying treated water,
Turbidity measuring means for measuring the turbidity of water to be treated;
A membrane filtration device that can remove chlorine-resistant pathogenic microorganisms and does not have a backwashing device;
An ultraviolet irradiation device;
Have
When the turbidity measured by the turbidity measuring means is greater than or equal to a predetermined reference value, at least the membrane filtration device is used, and when the turbidity is less than the reference value, at least the ultraviolet irradiation device is used. A water purification system characterized by purifying water. The water purification system according to claim 1 ,
A water purification system, further comprising a second membrane filtration device having a filtration membrane having a pore size larger than that of the filtration membrane used in the membrane filtration device and not having a backwashing device. The water purification system according to claim 2 ,
The turbidity measured by the turbidity measuring means, and for at least using the membrane filtration unit in the case of more than a reference value determined in advance, if it is less than the reference value is for at least using the second membrane filtration unit The water purification system characterized by purifying said to-be-processed water by this. It is a water purification system of any one of Claims 1-3 ,
A water purification system further comprising disinfectant injection means. A water purification method for purifying treated water,
A turbidity measuring step for measuring the turbidity of the water to be treated;
A filtration step of removing the chlorine-resistant pathogenic microorganisms and filtering the treated water with a filtration membrane that does not perform backwashing;
An ultraviolet irradiation step of irradiating the water to be treated with ultraviolet rays;
Including
Turbidity was the measurement is carried out at least the filtration step in the case of more than a reference value determined in advance, if it is less than the reference value, characterized in that for purifying the water to be treated by carrying out at least the ultraviolet irradiation step Water purification treatment method. The water purification method according to claim 5 ,
A water purification treatment method, further comprising a second filtration step of filtering the water to be treated with a second filtration membrane that is a filtration membrane having a pore size larger than the pore size of the filtration membrane and does not perform backwashing. The water purification method according to claim 6 ,
Turbidity was the measured, have lines at least the filtration step in the case of more than a reference value determined in advance, for purifying the water to be treated by the row Ukoto at least the second filtration step in the case of less than the reference value A water purification method characterized by that. The water purification method according to any one of claims 5 to 7 ,
The water purification method characterized by further including the disinfectant injection | pouring process.

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