Water filtration system

Abstract

To provide a water filtration system that can be made compact so as to be loaded in a loading space such as a truck for transportation while purifying non-drinking water to a drinkable level.SOLUTION: A water filtration system is assembled with a target water storage tank 10 for storage of target water, a lead-out passage 20, a target water pump 30, first filtration measurement means 40 for removal of dust from target water and filtration, a return reflux passage 50, a first valve 60, a branch flow passage 70, a second valve 80, second filtration measurement means 90 for addition of a rock extract to target water for flocculation of fine foreign matters and filtration, and drinking water take-out means 100 for take-out of target water (drinking water); opening the first valve 60 and closing the second valve 80 turns on a circulation mode where target water circulates between the target water storage tank 10 and the first filtration measurement means 40, and closing the first valve 60 and closing the second valve 80 turns on a drinking water take-out mode where drinking water is taken out from the drinking water take-out means 100.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a water filtration system that can filter unpotable water to make it potable. [Background technology]

[0002] In disaster areas such as earthquakes, lifelines such as water and electricity are often cut off. While electricity is often restored relatively quickly, it can take several months for water to be restored. During this time, disaster victims rely on water from water tankers and relief supplies for drinking water and other daily needs. However, it also takes time for the water from water tankers and relief supplies to reach the disaster victims. The above problems can be alleviated by using a portable water filtration system that can purify water from ponds, rivers, and pools in disaster areas on the spot to a level that makes it suitable for drinking and daily use.

[0003] In this regard, various water filtration systems that can be loaded onto a vehicle or the like and transported have been proposed. For example, Patent Document 1 proposes a mobile water purification facility that can be mounted on a truck as shown in Figure 1 of the document. As shown in Figure 2 of the document, the facility includes flocculant addition devices 4, 5, and 6 that add flocculant to raw water (water to be treated), a storage tank 8 that stores a mixed water of the raw water (water to be treated) and the flocculant, a first filter 9 immersed in the mixed water in the storage tank 8, a second filter 14 that further precisely filters the filtered water obtained by the first filter 9, and a third filter 20 that separates pure water from the filtered water obtained by the second filter. The third filter 20 uses a reverse osmosis membrane.

[0004] Furthermore, Patent Document 2 proposes a water treatment system for producing drinking water that is small enough to be mounted on a high-mobility vehicle and includes two RO membrane devices (a first RO membrane device 8 and a second RO membrane device 13) as shown in Figure 1 of the document. In the water treatment system for producing drinking water in the document, when the water to be treated is seawater, the water is passed through two RO membrane devices (a first RO membrane device 8 and a second RO membrane device 13) to produce drinking water, and when the water to be treated is freshwater, the water is passed through only one RO membrane device (the first RO membrane device 8) to produce drinking water. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 08-071567 [Patent Document 2] Patent No. 4113568 [Patent Document 3] Japanese Patent Application Publication No. 2023-172829 Summary of the Invention [Problem to be solved by the invention]

[0006] The mobile water purification equipment of Patent Document 1 and the drinking water production water treatment system of Patent Document 2 both use reverse osmosis membranes and can purify the treated water to a level close to pure. However, water filtration systems using reverse osmosis membranes generate a large amount of waste water to prevent clogging of the reverse osmosis membrane. Specifically, 30 to 50 percent of the treated water supplied to the reverse osmosis membrane is discarded. It is a waste to discard nearly half of the treated water that has been carefully collected from swimming pools and other facilities in disaster-stricken areas. However, if the discarded water is returned to the pools, the water will be purified while polluting the pool water, which could reduce the efficiency of water purification.

[0007] Furthermore, water filtration systems using reverse osmosis membranes have the disadvantage that the mineral components contained in the treated water are also removed, making the treated water tasteless after purification. Drinking water that contains a certain amount of mineral components such as calcium has a soft taste and is delicious to drink. In addition, treated water treated with reverse osmosis membranes is known to be highly corrosive and easily corrodes the pipes through which it flows.

[0008] The present applicants have proposed a water filtration system, as shown in FIG. 1 of Patent Document 3, in which a mineral supplying device MDI adds rock extract (minerals) to water that has passed through a first filter FL1 (a garbage filter) to flocculate contaminants contained in the water, and the water is then passed through a second filter FL2 (a flocculation filter) and a third filter FL3 (a flocculation filter) to produce drinking water. A primary tank 20 is provided upstream of the second filter FL2 (a flocculation filter), and a secondary tank 30 and a bubble supplying device FB (a fine bubble generator) are provided upstream of the third filter FL3 (a flocculation filter). The primary tank 20 mixes the water and the rock extract (minerals). The secondary tank 30 functions as a buffer tank for temporarily storing the water. The bubble supplying device FB (a fine bubble generator) generates fine bubbles in the water to flocculate smaller particles contained in the water.

[0009] The water filtration system described in Patent Document 3 can remove bacteria and other contaminants from the water (non-potable water such as river water, lake water, rainwater, or muddy water) by adding a rock extract (mineral components) to the water and passing it through a second filter FL2 (flocculation filter). Furthermore, fine bubbles are generated in the water before it passes through a third filter (flocculation filter), effectively removing even the fine particles that were not completely removed by the second filter FL2. Therefore, non-potable water such as river water, lake water, rainwater, or muddy water can be purified to a level suitable for drinking. Furthermore, since a certain amount of mineral components can be retained in the drinking water, delicious drinking water can be produced.

[0010] However, the water filtration system described in Patent Document 3 requires the use of an expensive fine bubble generator. Additionally, it requires the provision of multiple tanks (primary tank 20 and secondary tank 30) in addition to a tank (non-potable water tank 10) for storing untreated water. This makes it difficult to design the water filtration system compact enough to be transported on the back of a truck or the like.

[0011] The present invention has been made to solve the above problems, and provides a water filtration system that can purify non-potable water to a level that makes it potable, while also being designed to be compact enough to be transported on the back of a truck, etc. Another object of the present invention is to provide such a water filtration system without using a reverse osmosis membrane or a fine bubble generator. [Means for solving the problem]

[0012] The above issues are: a treated water storage tank for storing treated water that is not suitable for drinking (non-potable water); an outlet flow path for discharging the water to be treated from the water storage tank; a pump for transporting the water to be treated in the outlet flow path downstream; a first filtering means for filtering the water to be treated that has flowed through the outlet flow path and removed dust particles; a return flow path for returning the water to be treated that has passed through the first filtration means to the water storage tank; a first valve that opens and closes the return flow path; a branch flow path branched from the return flow path at a position upstream of the first valve; a second valve for opening and closing the branch flow path; a second filtering means for adding a rock extract to the water flowing through the branch flow path to aggregate minute foreign matter contained in the water, and filtering the water to a level where the water is suitable for drinking; a drinking water extraction means for extracting the water to be treated (hereinafter referred to as "drinking water") that has passed through the second filtration means; Equipped with By opening the first valve and closing the second valve, a circulation mode is established in which the water to be treated circulates between the water to be treated storage tank and the first filtration means, By closing the first valve and the second valve, the drinking water extraction mode is established in which the untreated water that has passed through the first filtration means is extracted from the drinking water extraction means without being returned to the untreated water storage tank. A water filtration system characterized by This is solved by providing

[0013] Here, "rock extract" refers to a liquid obtained by dissolving crushed rock in an inorganic acid, heating it, adjusting the pH with a citrate buffer solution, or the like, and then filtering to remove the precipitate. Rock extract is thus extracted directly from the rock, primarily from the source (rock). This allows for much easier extraction of mineral components than extraction from deep-sea water or biological sources such as plants and animals. It is also possible to extract a wide variety of mineral components. Additionally, by adjusting the solution with a citrate buffer, aggregates of mineral components that are inherently insoluble in water become water-soluble, making them more accessible. Furthermore, by increasing the amount of inorganic acid, the heating temperature can be increased, allowing for reliable and efficient extraction of the mineral components contained in the rock in the correct balance. When this rock extract (ionized mineral components) is added to the water to be treated, the tiny foreign matter in the water (such as tiny organic matter and bacteria) is inactivated (decomposed), coagulates, and precipitates.By removing these coagulations (sediments), clean drinking water can be obtained that is free of tiny foreign matter such as tiny organic matter and bacteria.

[0014] The water filtration system of the present invention uses a first filtration means that removes and filters debris, as well as a second filtration means that adds a rock extract to the water being treated to coagulate tiny foreign matter contained in the water and then removes the coagulates, so that non-potable water such as water from ponds, rivers, and pools can be thoroughly filtered to a level that makes it usable as drinking water.

[0015] Additionally, in the water filtration system of the present invention, the portion that occupies a certain volume is the treated water storage tank, eliminating the need for tanks equivalent to the primary and secondary tanks described above. Furthermore, the water filtration system of the present invention also eliminates the need for a fine bubble generator. This allows the water filtration system to be designed compactly, and it can be transported on the back of a truck or other vehicle. This makes the water filtration system highly useful in emergencies, such as when a disaster occurs, by enabling the water filtration system to be quickly transported to the affected area.

[0016] Furthermore, the water filtration system of the present invention can sufficiently filter non-potable water to drinking water quality without using a reverse osmosis membrane. This eliminates waste water and enables the effective use of water sources in disaster-stricken areas (such as ponds and pools). In addition, the treated drinking water becomes so-called "mineral water" containing mineral components. This makes it possible to make the resulting drinking water soft and delicious to drink. Furthermore, it is possible to prevent the drinking water from becoming too corrosive and to suppress corrosion of the various pipes and other components used in the water filtration system.

[0017] Furthermore, in the water filtration system of the present invention, by switching to the circulation mode, the water to be treated in the water storage tank can be continuously filtered by the first filtration means. In this circulation mode, the water to be treated in the water storage tank can be made considerably clear. Therefore, if the water to be treated in the water storage tank is switched to the drinking water extraction mode when it has become considerably clear, the clear water to be treated is supplied to the second filtration means, allowing for efficient filtration by the second filtration means. This makes it possible to obtain cleaner drinking water.

[0018] In the water filtration system of the present invention, the first filtration means is not particularly limited in its specific configuration as long as it can remove dust and debris, but it is preferable to use a sand filter. This allows the first filtration means to have an inexpensive and simple configuration while still being able to exert the necessary filtering action. Examples of sand filters include those that filter using sand (such as silica sand) packed into a column.

[0019] In the water filtration system of the present invention, the second filtration means is not particularly limited in its specific configuration as long as it can add rock extract to flocculate and remove minute foreign matter, but a rock extract storage tank for storing the rock extract; a rock extract pump that extracts the rock extract from the rock extract storage tank and transfers it to the branch flow path; A melt-blown filter provided in the branch flow path downstream of the rock extract pump; a hollow fiber membrane filter provided downstream of the melt-blown filter; An activated carbon filter installed downstream of the hollow fiber membrane filter; It is preferable to configure it as follows. This makes it possible to sufficiently filter non-potable water to the point where it can be used as drinking water, without using a reverse osmosis membrane or a fine bubble generator.

[0020] At this time, a flow meter for detecting the flow rate of the water to be treated flowing upstream of the rock extract pump in the branch flow path; When the flow rate detected by the flow meter is low, the output of the rock extract pump is reduced, If the flow rate detected by the flow meter is high, the output of the rock extract pump is increased. It is preferable to do so. As will be described later, there is an appropriate range for the mixing ratio of rock extract to the water to be treated, and by adopting the above configuration, the mixing ratio can be automatically adjusted to be within the appropriate range.

[0021] In the water filtration system of the present invention, it is preferable to provide two or more types of drinking water outlet means, including a faucet and a shower, so that the obtained drinking water can be taken out in an appropriate manner depending on its use. [Effects of the Invention]

[0022] As described above, the present invention provides a water filtration system that can purify non-potable water to a potable level while being designed compact enough to be transported on the back of a truck, etc. Furthermore, it is possible to provide such a water filtration system without using a reverse osmosis membrane or a fine bubble generator. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a diagram illustrating an example of a water filtration system according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] The water filtration system of the present invention will be described in more detail with reference to the drawings. The configuration described below is merely a preferred embodiment, and the technical scope of the water filtration system of the present invention is not limited to the configuration described below. The water filtration system of the present invention can be modified as appropriate within the scope of the invention.

[0025] 1. Overview of the water treatment system Fig. 1 shows an example of a water filtration system according to the present invention. As shown in Fig. 1, the water filtration system of this embodiment includes a treated water storage tank 10, an outlet flow path 20, a treated water pump 30, a first filtering means 40, a return flow path 50, a first valve 60, a branch flow path 70, a second valve 80, a second filtering means 90, and a drinking water extraction means 100.

[0026] The untreated water storage tank 10 is used to store untreated water that is not suitable for drinking (non-potable water) in advance. Examples of non-potable water that can be stored in the untreated water storage tank 10 include water from ponds, rivers, swimming pools, rain, etc. The non-potable water can be transferred from a water source (pond, river, swimming pool, etc.) to the untreated water storage tank 10 using a pump, bucket, etc. (not shown).

[0027] The outlet flow path 20 is a pipe for leading out the untreated water from the untreated water storage tank 10. The untreated water pump 30 is for transporting the untreated water in the outlet flow path 20 downstream. The first filtration means 40 removes debris from the untreated water that has flowed through the outlet flow path 20 and filters it (primary filtration). The return flow path 50 is a pipe for returning the untreated water that has passed through the first filtration means 40 to the untreated water storage tank 10. The first valve 60 is a valve for opening and closing the return flow path 50.

[0028] The branch flow path 70 is a pipe branching off from the return flow path 50 upstream of the first valve 60 (toward the first filtering means 40). The second valve 80 is a valve for opening and closing the branch flow path 70. The second filtering means 90 further filters (secondary filtration) the water to be treated that has undergone primary filtration by the first filtering means 40, thereby converting the water to drinking water suitable for drinking. As will be described later, the secondary filtration by the second filtering means 90 is performed by adding a rock extract (mineral components) to the water to be treated flowing through the branch flow path 70 to flocculate minute foreign matter contained in the water to be treated, and then removing the precipitated flocculates. The drinking water extraction means 100 is for extracting the water to be treated (drinking water) that has passed through the second filtering means 90.

[0029] As described above, the water filtration system of this embodiment obtains drinking water by subjecting the untreated water (non-potable water) stored in the untreated water storage tank 10 to primary filtration using the first filtration means 40 and secondary filtration using the second filtration means 90. The primary filtration using the first filtration means 40 only removes dust and dirt, and is unable to remove minute foreign matter such as bacteria. In contrast, the secondary filtration using the second filtration means 90 uses a rock extract (mineral components) to aggregate minute foreign matter in the untreated water, thereby removing even the minute foreign matter. This allows for the production of clean drinking water from which bacteria and other contaminants have been removed. Furthermore, the resulting drinking water is what is known as "mineral water" containing mineral components, making it soft and delicious to drink.

[0030] The water filtration system of this embodiment has two operating modes: a "circulation mode" and a "drinking water extraction mode," which will be described later.

[0031] The "circulation mode" is a mode in which the water to be treated in the water storage tank 10 is clarified by repeatedly performing primary filtration by the first filtration means 40. This circulation mode is executed by driving the water pump 30 with the first valve 60 open and the second valve 80 closed. In the circulation mode, the water to be treated flows from the water storage tank 10 through the outlet flow path 20, the first filtration means 40, and the return flow path 50, and is returned to the water storage tank 10 again.

[0032] The "drinking water extraction mode" is a mode in which drinking water is extracted by performing primary filtration by the first filtration means 40 followed by secondary filtration by the second filtration means 90. This drinking water extraction mode is executed by driving the treated water pump 30 with the first valve 60 closed and the second valve 80 open. In the drinking water extraction mode, the treated water is led out from the treated water storage tank 10 to the outlet flow path 20, passes through the first filtration means 40, enters the branch flow path 70 midway through the return flow path 50, passes through the secondary filtration means 90, and is then extracted from the drinking water extraction means 100.

[0033] As described above, the water filtration system has two operating modes: "circulation mode" and "drinking water extraction mode." After the water in the water storage tank 10 has been significantly purified in circulation mode, the system can be switched to drinking water extraction mode, whereby the purified water is supplied to the second filtration means 90. This allows for efficient filtration by the second filtration means 90 (a process in which a rock extract is added to the water to be treated to flocculate minute foreign matter contained in the water, and then the flocculated matter is removed). This makes it possible to obtain cleaner drinking water.

[0034] Furthermore, in this water filtration system, only the treated water storage tank 10 occupies a certain volume, and there is no need to install a fine bubble generator. This allows the water filtration system to be designed compact enough to be transported on the back of a truck or the like. This makes the water filtration system highly useful in emergencies such as disasters.

[0035] 2. Details of the water filtration system The detailed configuration of the water filtration system of this embodiment will be described.

[0036] 2.1 About the treated water storage tank As already mentioned, the untreated water storage tank 10 is used to store untreated water that is not suitable for drinking (non-potable water). The capacity of the untreated water storage tank 10 is not particularly limited, but if it is too small, drinking water can only be produced little by little. For this reason, the capacity of the untreated water storage tank 10 is usually set to 100 L or more. The capacity of the untreated water storage tank 10 is preferably set to 200 L or more, and more preferably to 300 L or more. However, on the other hand, if the capacity of the untreated water storage tank 10 is set too large, the water filtration system will become too large, which may make it difficult to transport the water filtration system on the back of a truck, etc. For this reason, the capacity of the untreated water storage tank 10 is usually set to 2000 L or less, and preferably to 1000 L or less.

[0037] 2.2 Pump for treated water In the circulation mode, the untreated water pump 30 circulates the untreated water between the untreated water storage tank 10 and the first filtration means 40. In the drinking water extraction mode, the untreated water pump 30 pumps the untreated water from the untreated water storage tank 10, passes through the first filtration means 40, and then passes through the branch flow path 70, passes through the second filtration means 90, and transports it to the drinking water extraction means 100. Various commercially available pumps can be used as the untreated water pump 30. The treatment capacity of the untreated water pump 30 varies depending on the capacity of the untreated water storage tank 10, etc., and is not particularly limited, but typically, a pump capable of transporting untreated water at a flow rate (pump flow rate) of 1,000 to 10,000 L / h is used. In the water filtration system of this embodiment, the flow rate (pump flow rate) of the untreated water pump 30 is approximately 8,000 L / h.

[0038] 2.3 First filtration means There are no particular limitations on the first filtering means 40, as long as it can filter and remove debris from the water to be treated. In the water filtration system of this embodiment, the first filtering means 40 is composed of a cartridge filter 41 and a sand filter 42. This allows the first filtering means to have an inexpensive and simple configuration while still being able to exert the necessary filtering action.

[0039] The cartridge filter 41 is a column containing a replaceable filter material (usually a cylindrical filter material) made of a mesh sheet. This allows it to capture foreign matter (foreign matter of a certain size) contained in the water to be treated. The mesh sheet of the cartridge filter 41 is preferably one with a mesh size of 100 to 200 (filtration particle size of approximately 70 to 200 μm). In the water filtration system of this embodiment, the filtration accuracy of the cartridge filter 41 is 40 μm.

[0040] The sand filter 42 is a column filled with sand (such as silica sand) for filtering. The particle size of the sand (such as silica sand) is typically approximately 0.1 to 2 mm, more specifically, approximately 0.5 to 1.2 mm (a particle size of 1 mm corresponds to 155 mesh (filtration particle size of approximately 100 μm)). By filling the column with approximately 10 to 50 kg, more specifically, approximately 20 to 30 kg, of this sand (such as silica sand), the water to be treated can be purified to a cleaning turbidity of 10 to 12 degrees. In the water filtration system of this embodiment, an INTEX sand filter (model number: SX2100) is used as the sand filter 42. In addition to a column 42a filled with sand, this sand filter 42 also includes a hair catcher 42b and a pump 42c. This pump 42c is used as the pump 30 for the water to be treated.

[0041] 2.4 Second filtration means The second filtration means 90 is not particularly limited as long as it can add rock extract (mineral components) to the water to be treated flowing through the branch flow path 70 to coagulate and remove minute foreign matter. In the water filtration system of this embodiment, the second filtration means 90 is composed of a rock extract storage tank 91, a rock extract pump 92, a flow meter 93, a melt-blown filter 94, a hollow fiber membrane filter 95, and an activated carbon filter 96.

[0042] The rock extract storage tank 91 is used to store the rock extract. In the water filtration system of this embodiment, rock is crushed, the crushed material is dissolved in an inorganic acid, and the resulting solution is heated at 100 to 150°C for 8 to 12 hours. The pH is then adjusted using a citrate buffer solution or the like, and the resulting liquid, from which the precipitate is removed by filtration, is stored as the rock extract in the rock extract storage tank 91. This rock extract is primarily extracted from the source of extraction (rock), and therefore contains a wide variety of mineral components.

[0043] Suitable rocks from which the rock extract is extracted are greenstones composed primarily of chlorite, epidote, and / or bakufan stone, a type of quartz porphyry or granite porphyry. Mineral components such as sulfur, iron, aluminum, magnesium, potassium, titanium, phosphorus, sodium, manganese, and calcium are extracted from greenstone. Mineral components such as silicon, aluminum, iron, magnesium, sodium, potassium, titanium, phosphorus, and manganese are extracted from bakufan stone.

[0044] Rock extracts extracted from greenstone or bakuhan stone contain, for example, the components shown in Table 1 below at the concentrations shown in the table. The actual components and concentrations vary depending on the location where the rock (greenstone, bakuhan stone, etc.) was collected, the extraction method, the extraction conditions, etc. Actual rock extracts also contain other components not shown in Table 1 below, although at low concentrations. [Table 1]

[0045] Among the mineral components contained in the rock extract, sulfur, iron, aluminum, magnesium, and potassium are presumed to be particularly effective. The mass ratio of sulfur, iron, aluminum, magnesium, and potassium in Table 1 above is approximately 32:5:2:1:1. Based on sulfur, the iron content is approximately 16 parts by mass, aluminum content is approximately 6 parts by mass, and magnesium and potassium content is approximately 3 parts by mass each per 100 parts by mass of sulfur. It is believed that the rock extract can exhibit its intended function if the ratio of each component per 100 parts by mass is within the ranges of 10-20 parts by mass of iron, 5-10 parts by mass of aluminum, and 1-5 parts by mass each of magnesium and potassium. It is believed that the rock extract can more preferably contain titanium, phosphorus, sodium, manganese, and calcium in addition to sulfur, iron, aluminum, magnesium, and potassium.

[0046] The amount of rock extract added to the water to be treated is not particularly limited, but adding too little rock extract may result in inefficient coagulation. The dilution ratio of the rock extract with the water to be treated is preferably kept to 30,000 times or less (0.003% or more of the rock extract relative to the total mass of the water to be treated after addition). The dilution ratio is more preferably kept to 20,000 times or less (0.005% or more of the above ratio), and even more preferably kept to 10,000 times or less (0.01% or more of the above ratio).

[0047] However, adding too much rock extract to the water being treated is not very effective. Therefore, it is preferable to dilute the rock extract with the water being treated by a factor of 1000 or more (a ratio of rock extract to the total mass of the water being treated after addition of 0.1% or less). The dilution factor is more preferably 3000 or more (a ratio of 0.03% or less), and even more preferably 5000 or more (a ratio of 0.02% or less).

[0048] The rock extract pump 92 extracts the rock extract from the rock extract storage tank 91 and transfers it to the branch flow path 70. While a motor-driven pump can be used as the rock extract pump 92, an electromagnetically driven volumetric pump (electromagnetic metering pump) that transfers fluid by the reciprocating motion of a diaphragm is preferable. The rock extract pump 92 may be configured to transfer the rock extract at a constant flow rate. However, the flow rate of the water to be treated flowing through the branch flow path 70 is not necessarily constant. As mentioned above, there is a preferred range for the dilution ratio of the rock extract with the water to be treated (5,000 to 10,000 times the narrowest range). However, if the rock extract is transferred at a constant flow rate, the dilution ratio may deviate from the desired range. For this reason, the water filtration system of this embodiment incorporates the following measures.

[0049] That is, a flow meter 93 is provided in the branch flow path 70 upstream of the point where the rock extract pump 92 is connected, to measure the flow rate of the water to be treated flowing through the branch flow path 70. This flow meter 93 is electrically connected to the rock extract pump 92. The rock extract pump 92 is set so that when the flow rate detected by the flow meter 93 is low, its output decreases, reducing the amount of rock extract transferred, and when the flow rate detected by the flow meter 93 is high, its output increases, increasing the amount of rock extract transferred. This makes it easier to maintain a constant dilution ratio of the rock extract (the ratio of rock extract added to the water to be treated) and prevents the dilution ratio from deviating from a desired range.

[0050] The melt-blown filter 94 is a column containing a filter element formed by thermally welding ultrafine fibers such as polypropylene into a cylindrical shape. The water to be treated is introduced into the column from the top, and foreign matter is captured as it flows from the inside to the outside of the cylindrical filter element. The filtration accuracy of the melt-blown filter 94 is typically 1 to 10 μm. In the water filtration system of this embodiment, the filtration accuracy of the melt-blown filter 94 is 5 μm.

[0051] The hollow fiber membrane filter 95 uses a collection of many hollow fibers (fibers with a hollow center) as a filter element. Polypropylene fibers are typically used for the hollow fibers. The hollow fibers are porous, with many micropores formed in their peripheral walls. When the water to be treated is brought into contact with the outside of the hollow fibers and passed through to the inside of the hollow fibers, foreign matter contained in the water to be treated is captured. The filtration accuracy of the hollow fiber membrane filter 95 is typically 0.005 to 0.1 μm. In the water filtration system of this embodiment, the filtration accuracy of the hollow fiber membrane filter 95 is 0.01 μm.

[0052] The activated carbon filter 96 is made by filling activated carbon such as coconut shell charcoal into a honeycomb core or a roll core, and covering the surface with nonwoven fabric, etc. This activated carbon filter can adsorb chlorine, organic matter, etc. contained in the water to be treated.

[0053] As described above, the second filtration means 90 is configured to add rock extract to the water to be treated, and then pass the water through the melt-blown filter 94, hollow fiber filter 95, and activated carbon filter 96. This allows the water that has been primarily filtered by the first filtration means 40 to be secondary filtered to a level that makes it suitable for drinking. Since a considerable amount of foreign matter has been removed from the water to be treated by the primary filtration by the first filtration means 40, secondary filtration by the second filtration means 90 can be carried out efficiently.

[0054] 2.5 Drinking water access means The drinking water extraction means 100 is used to extract treated water (drinking water) that has undergone secondary filtration by the second filtration means. In the water filtration system of this embodiment, two types of drinking water extraction means 100 are provided: a faucet 101 and a shower 102. By providing multiple types of drinking water extraction means 100 in this way, the obtained drinking water can be extracted in an appropriate manner depending on its use. A third valve 110 is provided in the flow path that supplies drinking water to the shower 102 to open and close the flow path. When the shower 102 is in use, this third valve 110 is opened, and when the shower 102 is not in use, this third valve 110 is closed.

[0055] 2.6 Circulation mode and drinking water extraction mode As already mentioned, in the water filtration system of this embodiment, the operating modes of the water filtration system include a "circulation mode" in which primary filtration is performed while circulating the water to be treated between the water storage tank 10 and the first filtration means 40, and a "drinking water extraction mode" in which the water to be treated that has completed primary filtration by the first filtration means 40 is subjected to secondary filtration by the second filtration means 90, and the resulting drinking water is extracted.

[0056] The time required for the circulation mode varies depending on the initial state of the water stored in the water storage tank 10, the capacity of the water storage tank 10, the transfer capacity of the water pump 30, the processing capacity of the first filtration unit 40, and other factors. However, if the circulation mode is performed for too long, it will take a long time from the start of filtration by the water filtration system of this embodiment until drinking water is extracted. For this reason, it is preferable to set the capacity of the water storage tank 10, the transfer capacity of the water pump 30, and the processing capacity of the first filtration unit 40 so that the circulation mode operation time is three hours or less. The circulation mode operation time is more preferably two hours or less, and even more preferably one hour or less. However, if the circulation mode operation time is too short, primary filtration may be insufficient. For this reason, it is preferable to ensure that the circulation mode operation time is 30 minutes or more.

[0057] Switching from the circulation mode to the drinking water extraction mode may be performed manually by manually checking the condition (turbidity, etc.) of the water to be treated in the water storage tank 10. However, in this case, an operator must go and check the condition of the water to be treated. Therefore, switching from the circulation mode to the drinking water extraction mode can also be performed automatically. For example, sensors (not shown) that detect the condition (turbidity, etc.) of the water to be treated can be provided in the water storage tank 10, the outlet flow path 20, the return flow path 50, etc., and the first valve 60 and the second valve 80 can be electrically switched when the value detected by the sensor reaches a predetermined value.

[0058] 3. Experiment To verify the effectiveness of the water filtration system of this embodiment in filtering potable water, we actually used the water filtration system to filter non-potable water. Rainwater was used as the non-potable water, and the water quality before and after filtration was compared. Thirteen items were tested: concentrations of "general bacteria," "E. coli," "nitrate nitrogen and nitrite nitrogen," "iron and its compounds," "chloride ions," "calcium, magnesium, etc. (hardness)," "evaporation residue," and "organic matter (total organic carbon (TOC))," as well as "pH," "taste," "odor," "color," and "turbidity." These tests were conducted in accordance with Ministry of Health, Labour and Welfare Notification No. 261 of July 22, 2003.

[0059] The experimental results are shown in Table 2 below. For reference, the water quality standards for each item are also shown in Table 2 below. [Table 2]

[0060] Table 2 above shows that before filtration, the four items of "general bacteria," "pH value," "color," and "turbidity" did not meet the water quality standards. However, after filtration, the non-potable water (rainwater) was purified to a level that fully met the water quality standards for all 13 items, including the four items. In particular, the "general bacteria" item was greater than 300 cells / mL before filtration, but was significantly reduced to 10 cells / mL after filtration. The "iron and its compounds" item also significantly decreased before and after filtration. Furthermore, the "color" item was 8 degrees before filtration, but was significantly reduced to less than 1 degree after filtration. Furthermore, the "turbidity" item was 2 degrees before filtration, but was significantly reduced to less than 0.5 degrees after filtration. These results demonstrate that the water filtration system of this embodiment has sufficient performance to filter non-potable water to produce drinking water.

[0061] The conditions for tasty water include an evaporation residue concentration of 30 to 200 mg / L and a hardness of 10 to 100 mg / L. Before filtration, the "evaporation residue" and "calcium, magnesium, etc. (hardness)" items were far from the tasty water conditions. However, after filtration, these items approached the lower limit of the tasty water conditions. The water filtration system of this embodiment is fully capable of satisfying the tasty water conditions by adjusting the amount of rock extract added, and it was found that the water filtration system of this embodiment can produce tasty drinking water. [Explanation of symbols]

[0062] 10. Treated water storage tank 20 Outlet channel 30 Treated water pump 40 First filtration means 41 Cartridge filter 42 Sand filter 42a Column 42b Hair Catcher 42c pump 50 Return Channel 60 First Valve 70 Branching Channel 80 Second valve 90 Second filtration means 91 Rock extract storage tank 92 Rock Extraction Pump 93 Flow meter 94 Meltblown Filter 95 Hollow fiber membrane filter 96 Activated carbon filter 100 Drinking water extraction means 101 Faucet 102 Shower 110 Third valve

Claims

1. a treated water storage tank for storing unpotable treated water; an outlet flow path for discharging the water to be treated from the water storage tank; a pump for transporting the water to be treated in the outlet flow path downstream; a first filtering means for filtering the water to be treated that has flowed through the outlet flow path and removed dust particles; a return flow path for returning the water to be treated that has passed through the first filtration means to the water storage tank; a first valve that opens and closes the return flow path; a branch flow path branched from the return flow path at a position upstream of the first valve; a second valve for opening and closing the branch flow path; a second filtering means for adding a rock extract to the water flowing through the branch flow path to aggregate minute foreign matter contained in the water, and filtering the water to a level where the water is suitable for drinking; a drinking water extraction means for extracting the water to be treated (hereinafter referred to as "drinking water") that has passed through the second filtration means; Equipped with By opening the first valve and closing the second valve, a circulation mode is established in which the water to be treated circulates between the water to be treated storage tank and the first filtration means, By closing the first valve and the second valve, the drinking water extraction mode is established in which the untreated water that has passed through the first filtration means is extracted from the drinking water extraction means without being returned to the untreated water storage tank. A water filtration system comprising:

2. 2. The water filtration system according to claim 1, wherein the first filtering means comprises a mesh filter and a sand filter.

3. The second filtering means a rock extract storage tank for storing the rock extract; a rock extract pump that extracts the rock extract from the rock extract storage tank and transfers it to the branch flow path; A melt-blown filter installed downstream of the rock extract pump in the branch flow path and, a hollow fiber membrane filter provided downstream of the melt-blown filter; An activated carbon filter installed downstream of the hollow fiber membrane filter; 3. The water filtration system of claim 2, comprising:

4. a flow meter for detecting the flow rate of the water to be treated flowing upstream of the rock extract pump in the branch flow path; When the flow rate detected by the flow meter is low, the output of the rock extract pump is reduced, If the flow rate detected by the flow meter is high, the output of the rock extract pump is increased.

4. The water filtration system of claim 3.

5. 5. The water filtration system according to claim 4, wherein the drinking water outlet means is provided in two or more types, including a faucet and a shower.

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