JP4661583B2 - Water purifier and water purification method - Google Patents

Description

  The present invention relates to a water purifier and a water purification method by treatment with activated carbon and treatment with a reverse osmosis membrane or a nanofiltration membrane.

  More specifically, by performing the pretreatment with a pretreatment cartridge having silver-impregnated activated carbon, biofouling of reverse osmosis membranes and nanofiltration membranes and functional layer deterioration due to residual chlorine are prevented, and the lifetime of the membrane cartridge is reduced. A water purifier that can suppress contamination of bacteria in the water storage tank for a long period of time by installing an antibacterial unit that elutes antibacterial metal ions by applying a voltage to the electrode on the downstream side of the membrane filtration cartridge, and It relates to water purification methods.

  In recent years, due to deterioration of water source water quality due to environmental pollution, various impurities have remained in tap water treated at a water supply station, causing off-flavor damage such as odor and mold odor. In particular, trihalomethane, which is a carcinogenic substance generated due to chlorine, is a problem even with a small amount of residue, and there are methods and equipment for purifying tap water before use in order to obtain safe and delicious drinking water and cooking water. It has been improved.

  For example, as one of the methods for purifying tap water, after filtration with activated carbon, filtration is performed using a reverse osmosis membrane (hereinafter referred to as “RO membrane”) or a nanofiltration membrane (hereinafter referred to as “NF membrane”). There is a way.

  Since RO membranes and NF membranes can remove many impurities such as organic substances, inorganic ions, bacteria, and viruses in water, it is possible to obtain fresh water with almost no impurities remaining. However, since these membranes have a lower amount of membrane filtration water per unit pressure per unit membrane area than microfiltration membranes and ultrafiltration membranes, many membrane areas and pressure pumps are required to increase the amount of membrane filtration water. is required. Therefore, in a relatively small membrane filtration device in which it is difficult to increase the membrane area, the membrane filtration treatment is continued even when the membrane filtration treated water is not used, and the membrane filtration treated water is stored in a water storage tank. A method of using treated water in a water storage tank is used.

  However, since the chlorine in the tap water does not remain in the membrane filtered water that has been membrane filtered and stored in the water storage tank, the membrane filtered water in the water tank is likely to be contaminated by germs and the like. Therefore, it is recommended that the water storage tank be cleaned regularly and the purified water staying in the water storage tank for a certain period be discarded. However, it is difficult to fully implement these in reality, and the effect is unknown and has not yet led to a fundamental solution.

  As a means for solving the contamination problem of membrane filtration water in the water storage tank, for example, as disclosed in Patent Document 1, the water subjected to the membrane filtration treatment is treated with silver-impregnated activated carbon or silver zeolite, and then stored in the water storage tank. A storage method has been proposed. However, with silver-impregnated activated carbon treatment, the amount of organic matter that can be a nutrient source for microorganisms adsorbed on the surface of activated carbon to which silver is not attached increases with the passage of water passage time. However, especially when the water is stagnant, there is a problem that bacteria are likely to grow on the activated carbon surface not attached with silver. In addition, in the silver zeolite treatment, the sustained release amount of silver ions is generally small and the life is short, so that it is difficult to impart sufficient silver ion concentration to water only by passing water. Here, in order to increase the sustained release amount of silver ions from the silver zeolite, it is sufficient to increase the filling amount of the silver zeolite. However, as the filling amount increases, it is necessary to increase the size of the cartridge. It is difficult to adopt. Another problem is that the cartridge needs to be frequently replaced in order to maintain a predetermined silver ion concentration.

  In order to solve such a problem, a method of immersing and installing silver zeolite in a water storage tank for storing membrane filtration treated water is conceivable. However, in this case, in order to make the silver ion concentration in the water tank uniform, it is necessary to constantly agitate the purified water in the water tank. Further, the purified water in the water tank is not used for a long time and the purified water in the water tank is not used. If the state is not replaced, silver ions continue to elute in the water storage tank, and there is a problem that the silver ion concentration exceeds the specified amount. Furthermore, since the sustained release amount of silver ions varies greatly depending on the quality and temperature of the purified water in the water storage tank, it is necessary to always finely adjust the silver zeolite filling amount in order to maintain a predetermined silver ion concentration.

  As described above, the conventional technique in which antibacterial treatment is performed using silver-impregnated activated carbon or silver zeolite is unsatisfactory as a measure against contamination of purified water in the water storage tank.

  In addition, since a polyamide-based resin is generally used as a material constituting the functional layer of the RO membrane or NF membrane, in order to prevent the functional layer from deteriorating with time due to residual chlorine in tap water, Before filtration with a membrane or NF membrane, tap water is pretreated with activated carbon or the like to remove residual chlorine.

  However, when water that has lost residual chlorine and has lost its antibacterial properties is subjected to membrane filtration, microorganisms are likely to grow on the membrane surface, so a slime substance (biofilm) mainly consisting of microorganisms and their metabolites on the membrane surface Adheres, that is, biofouling occurs, and there is a problem that the water permeability of the RO membrane and the NF membrane decreases.

  In order to solve such a problem, as disclosed in, for example, Patent Document 2, there is a method of performing film treatment after pretreatment is performed with silver-impregnated activated carbon to contain silver ions. However, in this case, it is possible to suppress biofouling of the RO membrane and NF membrane, but most of the silver ions in the water are removed by the RO membrane and NF membrane, so in the purified water after membrane treatment Silver ions hardly remain and it is difficult to prevent bacterial contamination of the purified water in the storage tank after membrane treatment.

Japanese Patent Laid-Open No. 10-85590 JP-A 61-54278

  The present invention solves the above-mentioned problems in the prior art, suppresses biofouling during membrane treatment with RO membranes and NF membranes, and prevents deterioration of the membrane functional layer due to residual chlorine in tap water. The purpose of the present invention is to provide a water purifier and a water purifying method that can extend the life of the membrane cartridge and can suppress contamination of germs in the water storage tank for storing the membrane-treated water for a long period of time. is there.

  In order to achieve the above object, the present invention adopts the following configuration.

  That is, a pretreatment cartridge for filtering water with silver-impregnated activated carbon, a membrane filtration cartridge for treating water treated with the pretreatment cartridge with a RO membrane or an NF membrane, and membrane filtration treatment with the membrane filtration cartridge A water purifier having a water storage tank for storing water, wherein an antibacterial unit for eluting antibacterial metal ions from an electrode to which a voltage is applied is disposed between the membrane filtration cartridge and the water storage tank. Container.

  At this time, the silver ion has a high antibacterial ability, has an action of killing various bacteria even in a very small amount, and has little harm to the human body even if taken orally. Therefore, at least silver ion is used as a metal ion having antibacterial properties. It is preferable to include. In order to control the silver ion concentration to a predetermined level even when the flow rate of the water subjected to the membrane filtration treatment is changed, a flow meter for measuring the flow rate of the membrane filtration treated water is provided between the membrane filtration cartridge and the antibacterial unit. It is preferable to provide an electric circuit which is arranged in the above and controls the current of the electrode of the antibacterial unit according to the flow rate output from the flow meter. Here, in order to prevent silver chloride from forming on the anode surface of the antibacterial unit, it is preferable to provide an electric circuit that reverses the polarity of the voltage applied to the electrode at predetermined time intervals.

  In addition, when turbidity such as iron rust is mixed in the tap water of the raw water, the membrane filtration process is performed by clogging the flow path on the primary side of the membrane filtration cartridge or thickening the cake layer on the membrane surface. Since the amount of water tends to decrease, it is preferable to dispose a filter unit cartridge having a filter with an average pore diameter of 0.1 to 10 μm on the upstream side of the membrane cartridge. Then, in order to reduce the number of cartridges and save the trouble of cartridge replacement, a cartridge having a structure in which the silver-impregnated activated carbon treatment part and the filter filtration part having an average pore diameter of 0.1 to 10 μm are arranged in series is used as the pretreatment cartridge. It is preferable.

  Furthermore, it is preferable to provide a water level sensor that detects the water level in the water storage tank, and a raw water supply valve that opens and closes by a signal from the water level sensor. In order to maintain a predetermined water recovery rate, the ratio of the amount of filtrate discharged from the membrane filtration cartridge and the amount of concentrated water is controlled to a substantially constant level. It is preferable to provide a concentrated water valve. When the tap water pressure is too low to secure a predetermined amount of membrane filtration water, it is preferable to provide a pressure pump upstream of the membrane filtration cartridge.

  In the water purification method of the present invention, tap water supplied at tap water pressure or at a water pressure increased by a pump is passed through a pretreatment cartridge loaded with silver-impregnated activated carbon, and then subjected to activated carbon filtration, and then RO membrane or NF. Membrane filtration water obtained by passing through an antibacterial unit that elutes antibacterial metal ions from an electrode to which voltage has been applied is passed through a membrane filtration cartridge having a membrane and then stored in a water storage tank. It is what.

  At this time, the metal ions having antibacterial properties contain at least silver ions, controlling the current of the electrodes of the antibacterial unit according to the flow rate output from the flowmeter that measures the flow rate of the membrane filtration treated water, It is preferable to reverse the polarity of the voltage applied to the electrode of the antibacterial unit every predetermined time. In addition, before treating tap water with silver-impregnated activated carbon, pre-filter with a filter having an average pore size of 0.1 to 10 μm, or after filtering tap water with silver-impregnated activated carbon and membrane with a membrane cartridge. Before the filtration treatment, it is preferable to carry out filtration treatment with a filter having an average pore size of 0.1 to 10 μm.

  Further, the silver impregnated activated carbon filtration unit and the filter filtration unit are filtered with a cartridge arranged in series, or the concentration of silver ions of water treated with the silver impregnated activated carbon is 5 μg / l or more, In addition, the chlorine concentration is 0.1 mg / l or less, the silver ion concentration of the membrane filtration water that has passed through the antibacterial unit is 5 μg / l or more and 100 μg / l or less, and the water level of the water storage tank When the water level reaches a predetermined water level or higher, it is preferable to automatically stop the membrane filtration process in the membrane cartridge or to control the ratio of the filtered water amount and the concentrated water amount of the membrane filtration cartridge to be constant.

  According to the present invention, tap water is treated with activated carbon and then membrane filtered with a membrane cartridge having an RO membrane or NF membrane, and then the membrane filtration treated water is stored in a water storage tank. Biofouling during membrane treatment with the membrane can be suppressed, deterioration of the functional layer due to residual chlorine can be prevented, and the life of the membrane filtration cartridge can be extended. Furthermore, contamination of germs in the water storage tank for storing the membrane filtrate can be suppressed over a long period of time.

  Hereinafter, the present invention will be described in more detail based on embodiments shown in the drawings. In addition, this invention is not limited to the following embodiments.

  Drawing 1 is an outline flow figure showing one embodiment of a water treatment process performed in a water purifier concerning the present invention.

  The water purifier of the present invention is used by being directly connected to a water pipe, for example, as shown in FIG. In FIG. 1, along tap water passage route, tap water open / close valve 1, filter filtration unit 2a for removing turbidity such as iron rust in tap water, and residual chlorine in tap water are removed. A pretreatment cartridge 2 which is arranged in series with a silver-impregnated activated carbon filtration unit 2b for eluting silver into water, and a membrane cartridge to ensure a predetermined amount of membrane filtration water even when the tap water pressure is too low 4, a pressure pump disposed on the upstream side, a membrane filtration cartridge 4 having an RO membrane or an NF membrane for membrane filtration of water treated by the pretreatment cartridge 2, and a flow rate of membrane filtration treated water of the membrane filtration cartridge 4 A flow meter 6 for measuring, an antibacterial unit 7 for eluting antibacterial metal ions into the membrane filtered water by applying a voltage to the electrode, a water storage tank 8 for storing the membrane filtered water after passing through the antibacterial unit 7, This The faucet 10 for taking out the purified water from the tank are provided. Further, a water level sensor for controlling the water level of the water storage tank 8 is provided in the concentrated water discharge path, and a concentrated water valve 5 for controlling the amount of concentrated water from the membrane cartridge 4 to a predetermined level in order to control the water recovery rate. 9 is provided. And the supply valve 1 of the raw | natural water (tap water) supplied to a water purifier is opened and closed by the signal from this water level sensor 9. FIG.

  Here, as the pretreatment cartridge 2 in which the filter filtration unit 2a and the silver impregnated activated carbon filtration unit 2b are integrally configured, for example, as shown in FIG. A 10 μm cylindrical filter is arranged, and an activated carbon filtration unit 2b in which a silver impregnated activated carbon is filled in a cylindrical container is arranged at the lower part (downstream side) of the cartridge. Here, the water filtered from the outside to the inside of the cylindrical filter has a structure that passes through the layer 2b of the silver-impregnated activated carbon, but the passing order of the filter and the silver-impregnated activated carbon may be reversed. .

  The filter layer used is not particularly limited as long as the average pore size is 0.1 to 10 μm, and may be any of a pleated type, a wind type, a depth type, etc., and the material is not particularly limited. However, any of polypropylene, polyester and the like may be used.

  The silver impregnated activated carbon to be used is not particularly limited as long as the silver ion concentration in the water after passing through the silver impregnated activated carbon layer 2b can be 5 μg / l or more and the chlorine concentration can be 0.1 mg / l or less. For example, silver impregnated activated carbon obtained by dissolving silver nitrate and magnesium nitrate in distilled water, spraying it uniformly on the activated carbon, and drying the resultant is mentioned. Further, the shape of the silver-impregnated activated carbon may be any of powder, granule, fiber, etc., but the water inflow portion and the water outflow portion are mesh structure so that the silver-impregnated activated carbon does not leak out of the pretreatment cartridge 2. It is preferable to cover with a nonwoven fabric filter or the like. The raw material of the activated carbon forming the silver-impregnated activated carbon may be coconut shell, wood, coal, petroleum coke or the like.

  The separation membrane used in the membrane cartridge 4 having the RO membrane or NF membrane used in the present invention has a desalination rate of 93% or more (evaluation conditions NaCl concentration: 500 mg / l, operating pressure: 0.1 MPa). Alternatively, an NF membrane having a desalination rate of 5% or more and less than 93% (evaluation conditions NaCl concentration: 500 mg / l, operating pressure: 0.1 MPa) can be selected and used.

  As the material of the separation membrane having such performance, in the case of RO membrane, polymer materials such as cellulose acetate, cellulose-based polymer, polyamide, and vinyl polymer can be used. In the case of NF membrane, polyamide-based, polypiperazine An amide type, a polyester amide type, or a crosslinked water-soluble vinyl polymer can be used. Typical RO membranes include cellulose acetate-based or polyamide-based asymmetric membranes and composite membranes having a polyamide-based active layer. Among them, polyvinyl alcohol is used as the surface layer of the polyamide-based active layer. The coated composite membrane is preferable because it has high exclusion performance, high water permeability, and high stain resistance.

  As the shape of the separation membrane, both the RO membrane and the NF membrane are preferably flat membranes or hollow fiber membranes. For example, the separation membrane has a thickness of 10 μm to 1 mm, and in the case of a hollow fiber membrane, the outer diameter is 50 μm to 4 mm. It is preferable to be in the range.

  The RO membrane filtration cartridge or NF membrane filtration cartridge 4 has a disk type in which spiral, pleated, plate-and-frame, and disk-shaped discs are stacked when the separation membrane is a flat membrane. In the case of a membrane, there is a cylindrical shape in which hollow fiber membranes are bundled in a U shape or an I shape and stored in a container, but any cartridge shape may be used in the present invention. These membrane filtration cartridges 4 are preferably operable at a low pressure from the viewpoint of reducing running costs.

  In the antibacterial unit 7 used in the present invention, for example, as shown in FIG. 3, two plate-like electrodes 11 are arranged facing each other in a form along the flow of the membrane filtration treated water from the inlet to the outlet. . The electrode is made of a metal material containing a metal that is the source of antibacterial metal ions, such as silver alone, an alloy of silver and copper, and an alloy of silver and zinc. Antibacterial metal ions such as silver ions are eluted from Silver ions and copper ions are preferred because they have high antibacterial ability, are effective in a very small amount, and do not cause harm to the human body even if used for a long period of time. However, silver ions are particularly preferable because they are less harmful to the human body.

  In addition, since the slightly soluble silver chloride scale is deposited on the surface of the anode by reacting with chloride ions in the membrane-treated water, the polarity of the voltage applied to the electrode is reversed every predetermined time to prevent this phenomenon. However, it is preferable that the metal compositions of both electrodes are substantially the same in order to always stabilize the elution concentration of silver ions even if they are reversed. In FIG. 3, the electrodes 11 are fixed by an insulator 13, and electric wires 12 are connected to the electrodes 11. It is preferable to cover the outer periphery of the electric wire 12 and the outer periphery of the joint portion between the electrode 11 and the electric wire 12 with an insulator 13 such as a resin so as not to come into contact with the membrane-filtered water.

  Since the tap water pressure is usually different in each household and fluctuates, a concentrated water valve 5 for controlling the amount of concentrated water from the membrane filtration cartridge to a predetermined level is arranged in the concentrated water discharge path. . In order to control the water recovery rate to a constant level even if the tap water pressure is different or fluctuates, the amount of membrane filtration treated water of the membrane cartridge 4 is proportional to the tap water pressure and is discharged from the concentrated water valve 5. It is preferable to use one whose concentrated water amount varies in proportion to the tap water pressure. For example, when it is desired to set the predetermined water recovery rate to 40%, the amount of concentrated water varies depending on the tap water pressure so that (water filtration treatment water amount) :( concentrated water amount) = 40: 60 at any tap water pressure It is preferable to select the concentrated water valve 5 that can be made to operate. If the amount of concentrated water controlled and discharged by the concentrated water valve 5 is constant regardless of fluctuations in the tap water pressure, when the tap water pressure is low, the water recovery rate decreases, and tap water is wasted. On the contrary, when the tap water pressure is high, the water recovery rate is increased, and there arises a problem that the scale of silica or calcium is easily deposited.

  What is necessary is just to set a water recovery rate suitably according to the tap water quality of each area so that a scale of silica, calcium, etc. may not precipitate. The concentrated water valve 5 is not particularly limited as long as it has a structure capable of controlling the passing water amount, and a normal throttle valve may be used. The flow meter 6 may be an impeller type, an area type, or the like as long as it can measure the flow rate of membrane filtration treated water.

  In the water purifier of the present invention described above, the water purification treatment is performed as follows.

  First, when it is detected that the water level sensor 9 in the water storage tank 8 has become equal to or lower than the predetermined lower limit water level L, a signal is sent to automatically open the raw water supply valve 1 so that the tap water is supplied to the filter filtration unit. 2a and the silver impregnated activated carbon filtration part 2b are supplied to the pretreatment cartridge 2 in which the two are integrated. By passing the tap water through the filter filtration unit 2a, turbidity such as iron rust in the tap water is removed, and by passing through the silver impregnated activated carbon filtration unit 2b, residual chlorine in the tap water is removed, Silver elutes.

  Next, the water treated by the pretreatment cartridge 2 is supplied to the RO membrane filtration cartridge or the NF membrane filtration cartridge 4. Since the residual chlorine is removed, the functional layer of the RO membrane or the NF membrane is prevented from being deteriorated with time, and the water quality of the membrane filtration treated water is prevented from being deteriorated with time. Further, since silver is eluted at 10 μg / l or more, the growth of miscellaneous bacteria such as general bacteria is suppressed, and the occurrence of biofouling is suppressed. However, since silver ions in water are almost removed by filtration through the RO membrane or NF membrane, almost no silver ions remain in the water filtered through the RO membrane or NF membrane.

  Therefore, the membrane-filtered water filtered by the RO membrane or NF membrane then flows into the antibacterial unit 7. The antibacterial unit 7 includes a pair of electrodes made of metal containing at least an antibacterial metal such as silver. By applying a voltage to the electrode in a state where the electrode is immersed in membrane-filtered water, a current is passed through the electrode. Antibacterial metal ions such as silver ions are eluted from the anode. Theoretically, according to Faraday's law, in proportion to the amount of current flowed, silver ions and the like are eluted in water, and the anode is depleted. Furthermore, a hardly soluble silver chloride scale is deposited on the surface of the anode by reacting with chloride ions in the membrane-treated water. Since scale precipitation hinders elution of silver ions and makes it difficult to maintain elution of predetermined silver ions, an electrical circuit that reverses the polarity of the voltage applied to the electrode every predetermined time is provided to reverse the polarity. By implementing the above, it becomes possible to prevent scale precipitation. The predetermined time is not particularly limited, but is preferably reversed within a range of 1 sec to 1 min in order to constantly stabilize the elution concentration of silver ions.

  Further, the flow rate of the membrane filtration treated water is measured by the flow meter 6, and an electric circuit for controlling the current of the electrode of the antibacterial unit 7 according to the flow rate output from the flow meter 6 is provided to carry out current control. . That is, when the flow rate of the membrane filtration treated water is large, the current is increased, and when the flow rate is small, the current is decreased, so that even if the flow rate of the membrane filtration treated water amount varies, a predetermined amount of silver ions (5 μg / l And 100 μg / l or less) can be eluted. The relationship between the current and the flow rate for eluting a predetermined amount of silver ions is appropriately set according to the filtration characteristics of the RO membrane or NF membrane.

  The reason why the lower limit of the silver ion concentration is preferably 5 μg / l is that the suppression of the growth of general bacteria can be expected greatly, and the upper limit of 100 μg / l or less is the USEPA (US Environmental Protection Agency). ) Is based on the water quality standards of the Safe Drinking Water Act. If the upper limit is set by the water quality standards stipulated by each country / region, that value is the upper limit. In addition, the silver ion concentration prescribed | regulated by this invention is the numerical value measured with the ICP emission-spectral-analysis apparatus.

  Membrane filtration treated water flowing out from the antibacterial unit 7 is stored in the water storage tank 8. Since the membrane-filtered water in the water storage tank 8 contains silver ions, the growth of germs such as general bacteria is suppressed even when left for a long time. On the other hand, water that has not been filtered through the RO membrane or NF membrane is discharged out of the system as concentrated water through the concentrated water valve 5.

  When the raw water supply valve 1 is opened and the water purification process is continued, the water level of the water storage tank 8 gradually rises, and when it is detected that the water level sensor 8 in the water storage tank 8 has reached the predetermined upper limit water level H, A signal is sent, the raw water supply valve 1 is automatically closed, and supply of tap water to the cartridge 2 and application of voltage to the electrodes of the antibacterial unit 7 are automatically stopped. When water is taken from the faucet 10 and the water level falls below the predetermined lower limit water level L, a signal is sent to automatically open the raw water supply valve 1 to supply the tap water to the pretreatment cartridge 2 and antibacterial. Application of voltage to the electrodes of the unit 7 is automatically restored.

  When the tap water pressure is too low to secure a predetermined amount of membrane filtration treatment water, it is preferable to provide the pressurization pump 3 in the previous stage of the membrane filtration cartridge 4 to pressurize the water before the membrane filtration cartridge. At this time, the pressure pump 3 is interlocked with the raw water supply valve 1, and the pressure pump 3 operates when the raw water supply valve 1 is open, and the pressure pump 3 stops when the raw water supply valve 1 is closed. It is preferable to do so. In FIG. 1, the faucet 10 is attached to the lower part of the water storage tank 8, and water is discharged by its own weight when the valve of the faucet 10 is opened, but the faucet 10 is attached to the upper part of the water storage tank 8. In such a case, a new pump may be provided below the water storage tank 8 so that the water can be pumped.

Example 1
Using a water purifier equipped with the water treatment process shown in FIG. 1, tap water having a water pressure of 300 kPa, a chromaticity of 4 degrees, an electric conductivity of 200 μS / cm, and a residual chlorine of 0.7 mg / l is obtained from Monday to Friday on weekdays. Was treated with 5 L of water every day and discharged out of the system.

The pretreatment cartridge 2 in the water purifier used here is a cartridge having the structure shown in FIG. 2, and the filter 2a is a wind filter (ADVANTEC, TCW-1N-PPS) having an average pore diameter of 1 μm, and silver-attached. As the activated carbon 2b, 100 g of granular activated carbon (Kuraray Chemical, Kuraray Coal T-SB 24/42 mesh) was used. As the membrane in the membrane cartridge 4, 1 m ² of NF membrane (Toray, UTC-60) was used. The pressurizing pump 3 was not used.

  The antibacterial unit 7 having the structure shown in FIG. 3 was used, and as the electrodes 11, pure silver (purity 99.9%) plates (size: 10 mm × 30 mm, thickness 1 mm) were arranged facing each other. As the water storage tank 8, a 6L capacity ABS-made resin tank was used. As the concentrated water valve 5, a throttle valve (FLOW420) manufactured by Danmark was used, and as the flow meter 6, an impeller type micro flow meter (FT2 series) manufactured by Hitech was used.

  In the control of the antibacterial unit 7, the polarity of the voltage applied to the electrode is reversed every 10 s, and the relationship between the current X (mA) and the flow rate Y (ml / min) is Y = 3000 (X−0.1 When the flow rate is less than 150 ml / min, the on-off valve 1 for supplying raw water is automatically closed, and supply of tap water to the cartridge 2 and application of voltage to the electrodes of the antibacterial unit 7 are automatically stopped. Such an electric circuit was obtained.

  As a result of continuing the water purification treatment for 5 days a week, the silver ion concentration of water sampled from the tap 10 for discharging the purified water is within a good range of 25 to 45 μg / l over a long period of 6 months from the start of operation. The general bacteria during that period were always 10 cfu / ml or less.

(Comparative Example 1)
Except that the antibacterial unit 7 was not installed, the same water purifier as in Example 1 was used, and a water purification treatment experiment was performed under the same conditions as in Example 1. As a result, the silver ion concentration of water sampled from the tap 10 is 1 to 3 μg / l for 3 months from the start of operation, and the general bacteria of water sampled from Tuesday to Friday is as high as 20 to 50 cfu / ml. In particular, the number of general bacteria collected on Monday morning was significantly higher than 100 cfu / ml.

(Comparative Example 2)
Instead of installing the antibacterial unit 7, instead, a column packed with 200 g of silver zeolite pellets (average particle size 1.5 mm) in which 80 g of silver zeolite (Sinanen Zeomic, AJ10D) was kneaded into 120 g of polyethylene resin was used. An experiment of water purification treatment was performed under the same conditions as in Example 1 except that the filtered water that was passed through was allowed to flow into the water storage tank 8 using the same water purifier as in Example 1.

  As a result, the silver ion concentration of water sampled from the tap 10 was 7 to 25 μg / l for one month from the start of operation, and the number of general bacteria during that period was always 10 cfu / ml or less. However, the silver ion concentration after 1 month from the start of operation is less than 5 μg / l, and the general bacteria of water collected from Tuesday to Friday is as high as 15 to 40 cfu / ml, especially on Monday at the beginning of the week. The general bacteria of the water in the water was remarkably high at 100 cfu / ml or more.

(Comparative Example 3)
Instead of installing the antibacterial unit 7, instead, a column packed with 30 g of granular activated carbon (Kuraray Chemical, Kuraray Coal T-SB 24/42 mesh) was used, and the membrane filtered water passed through the column was stored in the storage tank 8. Except that it was introduced, the same water purifier as in Example 1 was used, and an experiment of water purification treatment was performed under the same conditions as in Example 1.

  As a result, the silver ion concentration of water collected from the tap 10 was 15 to 80 μg / l for 15 days from the start of operation, and the general bacteria at that time were always 10 cfu / ml or less. However, even though the silver ion concentration after 15 days was 5 μg / l or more, the general bacteria collected from Tuesday to Friday was as high as 25-60 cfu / ml, especially on Monday at the beginning of the week. The general bacteria of the collected water was remarkably high at 100 cfu / ml or more.

  The water purifier and the water purifying method according to the present invention are useful as a small water purifier for improving the water quality and obtaining safe and high-quality water when tap water is used for beverages and cooking.

It is a schematic flowchart which shows one embodiment of the water treatment process performed in the water purifier which concerns on this invention. It is a structure schematic (front sectional drawing) which shows one implementation structure of the pre-processing cartridge integrated in the water purifier which concerns on this invention. It is a structure schematic diagram showing one implementation structure of an antibacterial unit built in a water purifier concerning the present invention, and shows a front section, a left side section, and a plane section, respectively.

Explanation of symbols

1: Open / close valve for supplying raw water (tap water) 2: Pretreatment cartridge 2a: Filter filtration unit 2b: Silver impregnated activated carbon filtration unit 3: Pressurization pump 4: Membrane filtration cartridge 5: Concentrated water valve 6: Flow meter 7 : Antibacterial unit 8: Water storage tank 9: Water level sensor 10: Faucet for water purification 11: Electrode 12: Electric wire 13: Insulator

Claims (20)

A pretreatment cartridge having an activated carbon treatment section for filtering water with silver impregnated activated carbon, a membrane filtration cartridge for subjecting water treated with the pretreatment cartridge to a membrane filtration treatment with a reverse osmosis membrane or a nanofiltration membrane, and the membrane filtration cartridge A water purifier having a water storage tank for storing water that has been subjected to membrane filtration treatment with an antibacterial unit that elutes antibacterial metal ions from an electrode to which a voltage is applied, between the membrane filtration cartridge and the water storage tank. A water purifier characterized by being placed in between. The water purifier according to claim 1, wherein the metal ions having antibacterial properties include at least silver ions. An electric circuit that arranges a flow meter for measuring the flow rate of the water subjected to membrane filtration between the membrane filtration cartridge and the antibacterial unit, and controls the current of the electrode of the antibacterial unit according to the flow rate output from the flow meter The water purifier according to claim 1 or 2, wherein the water purifier is provided. The water purifier according to any one of claims 1 to 3, wherein the antibacterial unit includes an electric circuit that reverses the polarity of a voltage applied to the electrode every predetermined time. The water purifier according to any one of claims 1 to 4, wherein a filter filtration cartridge including a filter having an average pore diameter of 0.1 to 10 µm is arranged on the upstream side of the membrane filtration cartridge. 5. The cartridge according to claim 1, wherein the pretreatment cartridge is a cartridge having a structure in which the activated carbon treatment part and a filter filtration part having an average pore diameter of 0.1 to 10 μm are arranged in series. Water purifier. The water purifier according to any one of claims 1 to 6, further comprising: a water level sensor that detects a water level in the water storage tank; and a raw water supply opening / closing valve that opens and closes according to a signal from the water level sensor. The water purifier according to any one of claims 1 to 7, further comprising a concentrated water valve for controlling a flow rate of the concentrated water discharged from the membrane filtration cartridge. The water purifier according to any one of claims 1 to 8, wherein a pressure pump is provided upstream of the membrane filtration cartridge. Membrane filtration cartridge having a reverse osmosis membrane or a nanofiltration membrane after passing tap water supplied at a tap water pressure or with a water pressure increased by a pump through a pretreatment cartridge loaded with silver-impregnated activated carbon A water purification method characterized by storing membrane filtration treated water obtained by passing an antibacterial unit that elutes antibacterial metal ions from an electrode to which a voltage is applied, in a water storage tank after passing the membrane through a membrane filtration treatment. The water purification method according to claim 10, wherein the metal ions having antibacterial properties include at least silver ions. The water purification method according to claim 10 or 11, wherein the flow rate of the membrane filtration treated water is measured with a flow meter, and the current of the electrode of the antibacterial unit is controlled according to the flow rate of the membrane filtration treated water. The water purification method according to any one of claims 10 to 12, wherein the polarity of the voltage applied to the electrode of the antibacterial unit is reversed every predetermined time. The water purification method according to any one of claims 10 to 13, wherein the tap water before being filtered with silver-impregnated activated carbon is previously filtered with a filter having an average pore size of 0.1 to 10 µm. The water filtered through silver impregnated activated carbon is filtered through a filter having an average pore size of 0.1 to 10 μm before membrane filtration through a membrane filtration cartridge. Water purification method. The water purification method according to claim 14 or 15, wherein the water is filtered by a cartridge in which the silver-impregnated activated carbon filtration unit and the filter filtration unit are arranged in series. 17. The purified water according to claim 10, wherein a silver ion concentration of water treated with activated carbon by the pretreatment cartridge is 5 μg / l or more and a chlorine concentration is 0.1 mg / l or less. Method. 18. The water purification method according to claim 10, wherein the silver ion concentration of the membrane filtration treated water that has passed through the antibacterial unit is 5 μg / l or more and 100 μg / l or less. The water purification method according to any one of claims 10 to 18, wherein when the water level of the water storage tank reaches a predetermined water level or higher, the membrane filtration process in the membrane cartridge is automatically stopped. The water purification method according to any one of claims 10 to 19, wherein the ratio of the amount of filtrate water and the amount of concentrated water coming out of the membrane filtration cartridge is controlled within a substantially constant range.

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