Rainwater Treatment System

Abstract

The object of the present invention is to provide a rainwater treatment system and a rainwater treatment method capable of removing impurities contained in rainwater and producing pure water at low cost without requiring an external power source. [Solution] The rainwater treatment system 1 is composed of a rainwater storage tank 10, a first filtration tank 20, a second filtration tank 30, and a filtered water storage tank 40. Of the impurities contained in the rainwater that flows into the first filtration tank 20, impurities with a high specific gravity are deposited at the bottom, while impurities with the same specific gravity are captured by the first filter 21. Then, impurities with a low specific gravity are discharged outside the system as overflow water. This makes it possible to efficiently remove impurities without requiring external power and produce highly pure water.

Description

[Technical field]

[0001] The present invention relates to a rainwater treatment system and a rainwater treatment method, and more particularly to a rainwater treatment system and a rainwater treatment method capable of removing impurities contained in rainwater and producing pure water at low cost without requiring an external power source. [Background technology]

[0002] In recent years, a rainwater treatment system for reusing rainwater has been proposed. As shown in Patent Document 1, this rainwater treatment system pumps up rainwater stored in a rainwater storage tank and filters it with a filtration device to remove impurities contained in the rainwater and produce highly pure filtered water, which can be used for various purposes such as car washing water, industrial water, spraying on plants, dry mist, and emergency water for daily life in the event of a disaster. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-132299 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the storm water treatment system disclosed in Patent Document 1 requires an external power source to be used to operate the system, which results in high operating costs and makes the system unusable during power outages caused by disasters such as earthquakes.

[0005] The present invention has been devised in consideration of the above points, and an object of the present invention is to provide a rainwater treatment system and a rainwater treatment method that can remove impurities contained in rainwater and produce pure water at low cost without requiring external power. [Means for solving the problem]

[0006] In order to achieve the above-mentioned objective, the rainwater treatment system of the present invention comprises a first filtration tank having a first filter that filters rainwater that flows in, a rainwater channel that introduces rainwater into the first filtration tank, an overflow channel that drains overflow water from the first filtration tank when the water level in the first filtration tank exceeds a predetermined water level, and a drainage channel connected to the overflow channel that drains the overflow water outside the system.

[0007] Here, by providing a first filtration tank having a first filter that filters the flowing-in rainwater, impurities contained in the rainwater that flows into the first filtration tank, impurities with a specific gravity similar to that of the rainwater, are captured by the first filter.

[0008] In addition, by providing an overflow water channel that drains overflow water from the first filtration tank when the water level in the first filtration tank exceeds a predetermined water level, impurities that have a lighter specific gravity than rainwater and cannot be captured by the first filter can be drained through the overflow water channel.

[0009] In addition, by providing a drainage channel connected to the overflow channel for draining overflow water outside the system, the overflow water can be drained from the drainage channel to the outside of the system via the overflow channel.

[0010] Furthermore, in the case where a filtered water storage tank is provided for storing the filtered water filtered in the first filtration tank, the filtered water filtered in the first filtration tank can be stored in the filtered water storage tank and used for various purposes, such as car washing water, industrial water, spraying on plants, dry mist, or emergency water for daily use in the event of a disaster.

[0011] In addition, in the case where there is a filtration water channel connected at one end to the first filtration tank and at the other end to the filtrate water storage tank, which sends the filtrate filtered by the first filter to the filtrate water storage tank, the filtrate filtered in the first filtration tank can be constantly supplied to the filtrate water storage tank through the filtration water channel.

[0012] In addition, if the end of the rainwater channel facing the first filtration tank is blocked and slits are formed along the circumferential direction of the side surface near the end, the rainwater flowing in from the rainwater channel will form a spiral flow when it spurts out from the slits. This spiral flow causes the rainwater to flow along the inner wall of the first filtration tank, increasing the contact area between the rainwater and the first filter, allowing the first filter to efficiently capture impurities contained in the rainwater.

[0013] In addition, if the bottom of the first filtration tank has an openable valve for draining relatively heavy impurities contained in rainwater out of the system, the impurities accumulated at the bottom of the first filtration tank can be drained out of the system by opening and closing the valve.

[0014] In addition, if the top of the first filtration tank has an inspection cover that opens and closes the inspection hatch for inspecting the internal condition, periodic inspection work inside the first filtration tank can be performed. Furthermore, work such as replacing the first filter can be easily performed by opening and closing this inspection cover.

[0015] In addition, the storm water channel is provided with a rainwater storage tank that temporarily stores rainwater, and when rainwater overflows from the rainwater storage tank and flows into the first filtration tank, impurities with a relatively high specific gravity accumulate at the bottom of the rainwater storage tank, so that rainwater from which some of the impurities have been removed can be made to flow into the first filtration tank. This reduces the impurities captured by the first filter, preventing deterioration of the first filter over time and reducing the operating costs of the storm water treatment system.

[0016] In addition, if the bottom of the rainwater storage tank has an openable valve for draining relatively heavy impurities contained in the rainwater out of the system, the impurities accumulated at the bottom of the rainwater storage tank can be drained out of the system by opening and closing the valve.

[0017] Furthermore, if the filtered water channel is provided with a second filtration tank including a second filter that further filters the filtered water sent from the first filtration tank, the two-stage filtration by the first filter and the second filter can capture impurities that could not be captured by the first filter due to, for example, deterioration of the first filter. Also, by changing the materials of the first filter and the second filter, various impurities contained in rainwater can be efficiently captured.

[0018] In addition, the filtration water channel has a first filtration water channel connecting the first filtration tank and the second filtration tank, and a second filtration water channel connecting the second filtration tank and the filtrate water storage tank, and when the end of the first filtration water channel facing the inside of the second filtration tank is blocked and a slit hole is formed along the circumferential direction of the side surface near the end, the rainwater flowing from the first filtration water channel into the second filtration tank forms a spiral flow when it sprays out from the slit hole. This spiral flow causes the rainwater to flow along the inner wall of the second filtration tank, increasing the contact area between the rainwater and the second filter, and the impurities contained in the rainwater can be efficiently captured by the second filter.

[0019] Furthermore, when the inner walls of the first filtration tank and the second filtration tank are made of a resin material and the outer walls are made of a thermal insulating material, it is possible to prevent components of the inner wall material from dissolving into the filtered water and to prevent the filtered water from deteriorating due to the influence of the outside temperature.

[0020] In order to achieve the above-mentioned object, the rainwater treatment method of the present invention comprises the steps of: flowing rainwater from a rainwater channel into a first filtration tank; filtering the rainwater with a first filter installed in the first filtration tank to produce filtered water; and, when the water level in the first filtration tank exceeds a predetermined water level, discharging the rainwater that has overflowed from the first filtration tank together with impurities having a relatively low specific gravity through a drainage channel to the outside of the system.

[0021] Through the above process, impurities with different specific gravities contained in rainwater can be efficiently removed to produce highly pure water without the need for external power.

[0022] Furthermore, in the case where the process for generating filtered water includes a process for sending the filtered water produced in the process for generating filtered water to a filtered water storage tank through a filtration water channel, the filtered water filtered in the first filtration tank can be stored in the filtered water storage tank and used for various purposes, such as car washing water, industrial water, spraying on plants, dry mist, or emergency water for daily use in the event of a disaster.

[0023] Furthermore, if the filtration water channel is provided with a second filtration tank including a second filter, and the process of sending the filtered water through the filtration water channel to the filtrate water storage tank includes a process of further filtering the filtrate water sent from inside the first filtration tank with the second filter, and sending the filtrate water to the filtrate water storage tank, the two-stage filtration by the first filter and the second filter can capture impurities that could not be captured by the first filter due to, for example, deterioration of the first filter. Also, by changing the materials of the first filter and the second filter, various impurities contained in rainwater can be efficiently captured.

[0024] Furthermore, if the step of flowing rainwater into the first filtration tank includes a step of flowing rainwater overflowing from a rainwater storage tank that temporarily stores rainwater into the first filtration tank, impurities with a relatively high specific gravity will accumulate at the bottom of the rainwater storage tank, so that rainwater from which some of the impurities have been removed can be flowed into the first filtration tank. This reduces the impurities captured by the first filter, preventing deterioration of the first filter over time and reducing the operating costs of the rainwater treatment system.

[0025] Furthermore, if the process of flowing rainwater from the rainwater channel into the first filtration tank includes a process of draining the rainwater stored in the rainwater storage tank to the outside of the system through a drainage channel when it is detected that the first filtration tank is full, impurities with a high specific gravity that have accumulated at the bottom of the rainwater storage tank are drained to the outside of the system through the drainage channel when the first filtration tank is full, and a stationary state in which rainwater does not flow into the first filtration tank can be created. Then, in the first filtration tank, the impurities attract each other due to van der Waals forces and settle to the bottom as clumps of impurities, facilitating the separation of the water and the impurities. Effect of the Invention

[0026] The rainwater treatment system and the rainwater treatment method according to the present invention can remove impurities contained in rainwater and produce pure water at low cost without requiring an external power source. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a front view of a storm water treatment system according to an embodiment of the present invention. [Diagram 2] 1 is a side view of a storm water treatment system according to an embodiment of the present invention. [Diagram 3] 1 is a plan view of a storm water treatment system according to an embodiment of the present invention. [Figure 4] FIG. 2 is a front view showing the internal structure of a first filtration tank according to the embodiment of the present invention. [Diagram 5] FIG. 2 is a plan view showing the internal structure of a first filtration tank according to the embodiment of the present invention. [Figure 6] FIG. 4 is a front view showing the internal structure of a second filtration tank according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, a rainwater treatment system and a rainwater treatment method according to an embodiment of the present invention will be described with reference to the drawings to facilitate understanding of the present invention. In the following description, the direction going upward is defined as "upward," the direction opposite to "upward" as "downward," the axial direction represented by "upward" and "downward" as the vertical direction, and the direction perpendicular to the vertical direction as the horizontal direction. First, the overall configuration of a rainwater treatment system 1 according to an embodiment of the present invention will be described with reference to Figs. 1 to 3.

[0029] The rainwater treatment system 1 is connected to a downspout P1 constituting a gutter for draining rainwater accumulated on the roof of a building to the ground, for example, and is composed of a rainwater storage tank 10 for temporarily storing rainwater, a first filtration tank 20 for removing impurities contained in the rainwater supplied from the rainwater storage tank 10 with a first filter 21 to generate filtered water, a second filtration tank 30 for removing impurities that cannot be removed by the first filter 21 with a second filter 31, and a filtered water storage tank 40 for storing the filtered water generated in the first filtration tank 20 and the second filtration tank 30 for use in various applications. The detailed structure of each component will be described below.

[0030] [Rainwater storage tank] The rainwater storage tank 10 is substantially cylindrical, and its upper end is connected to a branched passage P2 that branches off from a vertical spout passage P1 that constitutes a rain gutter, and the rainwater branched off from the vertical spout passage P1 flows into the rainwater storage tank 10 through this branched passage P2. A valve V1 is provided in the branched passage P2, and the amount of rainwater flowing from the vertical spout passage P1 into the rainwater storage tank 10 is adjusted.

[0031] The bottom of the rainwater storage tank 10 is connected to a drainage channel P3 via a valve V2, and this drainage channel P3 is connected below the downspout channel P1. The valve V3 is opened when performing maintenance on the rainwater storage tank 10 or when cleaning the inside.

[0032] Valve V2 is normally closed so that rainwater stored in the rainwater storage tank 10 is not discharged outside the system through drainage channel P3. Rainwater flowing in from the branch channel P2 is temporarily stored in the rainwater storage tank 10. At this time, impurities contained in the rainwater that are relatively heavy in specific gravity compared to the rainwater are deposited at the bottom of the rainwater storage tank 10. These deposited impurities can be drained outside the system through drainage channel P3 by opening valve V2 during regular inspection.

[0033] By opening the valve V2, most of the impurities accumulated at the bottom of the rainwater storage tank 10 are drained together with the rainwater through the drainage channel P3 to the outside of the system, but some impurities and rainwater remain at the bottom. These remaining impurities and rainwater can be drained to the outside of the system through the valve V3 by opening the valve V3.

[0034] One end of a rainwater channel P4 is connected to the top of the rainwater storage tank 10, and the other end of the rainwater channel P4 is connected to the first filtration tank 20. When rainwater accumulates in the rainwater storage tank 10 and becomes full, the rainwater that overflows from the rainwater storage tank 10 is sent to the first filtration tank 20 through the rainwater channel P4.

[0035] Here, the rainwater storage tank 10 does not necessarily have to be provided. For example, the rainwater channel P4 may be connected to the downspout channel P1, and rainwater may flow from the downspout channel P1 into the first filtration tank 20. However, by providing the rainwater storage tank 10, as described above, impurities contained in the rainwater that are relatively heavier in specific gravity than the rainwater can be deposited at the bottom of the rainwater storage tank 10, and the rainwater from which the heavy impurities have been removed can be allowed to flow into the first filtration tank 20.

[0036] In this way, by allowing rainwater from which heavy impurities have been removed to flow into first filtration tank 20, clogging of first filter 21 can be prevented and the replacement cycle of the first filter can be reduced.

[0037] [1st filtration tank] The first filtration tank 20 is roughly cylindrical with an inner wall made of resin material and an outer wall made of insulating material, and one end of a rainwater channel P4, to which overflow water from the rainwater storage tank 10 is supplied, is connected to a predetermined position on the upper side so that it faces the inside.

[0038] Here, the inner wall of the first filtration tank 20 does not necessarily have to be made of a resin material. However, if the inner wall is made of a metal such as stainless steel, there is a risk that metal components will dissolve over many years of use and become mixed into the filtered water. On the other hand, if the inner wall is made of a resin material, there is a low possibility that impurities will dissolve over many years of use, so from the viewpoint of maintaining a constant quality of the filtered water, it is preferable that the inner wall be made of a resin material.

[0039] Similarly, the outer wall does not necessarily have to be made of a heat insulating material, but the quality of the filtered water in the first filtration tank 20 changes due to the influence of the outside air temperature when the temperature is high in summer or low in winter. Therefore, by making the outer wall out of a heat insulating material, the temperature inside the first filtration tank 20 can be kept constant without being influenced by the outside air temperature. Therefore, from the viewpoint of keeping the quality of the filtered water constant, it is preferable that the outer wall be made of a heat insulating material.

[0040] As shown in FIG. 4, the first filter 21 is an elongated cylinder with a cavity formed in the center along the length direction for the filtered water to pass through. The top is open and the upper and lower ends in the direction of the central axis are firmly fixed within the first filtration tank 20 via brackets 22, 23.

[0041] Here, the first filter 21 does not necessarily have to be a vertically long cylindrical shape. However, by forming the first filter 21 in a vertically long cylindrical shape with a cavity formed inside, the head pressure can be secured and the filtered water can be efficiently sent to the second filtration tank 30 described later.

[0042] A connecting pipe 24 is connected to the first filter 21 on the bracket 23 supporting the first filter 21 for sending the filtered water filtered by the first filter 21 to the filtration water passage P5, and rainwater that passes through the first filter 21 becomes filtered water and passes through the cavity, via the connecting pipe 24, and then through the filtration water passage P5 to be sent from the first filtration tank 20 to the second filtration tank 30.

[0043] The first filter 21 employs a filter cloth made of nonwoven or woven fabric, and has, for example, a two-layer structure consisting of an inner layer and an outer layer. Since the mesh sizes of the inner layer filter cloth and the outer layer filter cloth are different, minute gaps are formed, which enables impurities of various sizes to be captured and clogging to be suppressed.

[0044] Here, the configuration of the first filter 21 is not necessarily limited to the above, and may be appropriately selected from known filtering materials. Note that, by forming a large number of fine gaps on the surface of the first filter 21 as in the embodiment of the present invention, the filtering area is ensured and the differential pressure of the head pressure can be dispersed, thereby preventing clogging due to captured impurities.

[0045] An overflow waterway P6 is connected to the top of the first filtration tank 20 to drain overflow water when the water level in the first filtration tank 20 is close to full capacity. The overflow waterway P6 bends downward outside the first filtration tank 20 and is connected to the downspout channel P1 via the drainage channel P3.

[0046] 5 is a plan view showing the internal structure of the first filtration tank 20. The end of the rainwater channel P4 is closed, and slit holes S are formed in a predetermined range along the circumferential direction of the side surface near the end. Rainwater spurting out from these slit holes S forms a vortex flow inside the first filtration tank 20.

[0047] As shown in the schematic diagram of Figure 4, when rainwater is introduced through the slit holes S, it spurts out toward the inner wall of the first filtration tank 20 (dotted arrow in Figure 4). When it collides with the inner wall, the flow changes direction and becomes a rotating flow that flows downward in a spiral shape. At this time, impurities with a high specific gravity among the impurities contained in the rainwater flow along the inner wall of the first filtration tank 20 due to the centrifugal separation effect and accumulate at the bottom.

[0048] On the other hand, impurities with the same or lighter specific gravity are guided toward the center of the first filtration tank 20 together with the rainwater (white arrow in FIG. 4). The rainwater guided toward the center of the first filtration tank 20 comes into contact with the first filter 21. At this time, the impurities contained in the rainwater are captured as it passes through the filter cloth, and the filtered water that has permeated the filter cloth is sent from the internal cavity of the first filter 21 through the connecting pipe 24 to the filtration water channel P5.

[0049] When the first filtration tank 20 becomes full and the supply of rainwater from the rainwater channel P4 is stopped, impurities attract each other in the first filtration tank 20 due to van der Waals forces and form heavier lumps that sink and accumulate at the bottom, while impurities with the same specific gravity are captured by the first filter 21. Impurities with lighter specific gravity are either captured by the first filter 21, or the impurities that are not captured float on the water surface in the first filtration tank 20.

[0050] Impurities floating on the water surface are drained as overflow water from the above-mentioned overflow water channel P6 and drained out of the system. On the other hand, impurities that have a high specific gravity and have accumulated at the bottom can be drained out of the system by opening the valve V4 provided at the bottom of the first filtration tank 20 during regular inspection, for example. The valve V4 may be connected to the drainage channel P3, and the impurities may be drained out of the system from the valve V4 via the drainage channel P3.

[0051] An inspection lid 25 capable of completely closing the upper opening of the first filter 21 is provided on the upper part of the first storage tank 20, and during maintenance, an operator can open this inspection lid 25 to check the internal condition or to replace the first filter 21. Furthermore, by supplying filtered water from the upper opening of the first filter 21 with the inspection lid 25 open, impurities adhering to the first filter 21 can be cleaned by backwashing.

[0052] [Second filtration tank] The second filtration tank 30 is installed on the filtration water passage P5 between the first filtration tank 20 and the filtrate water storage tank 40 described below, and the second filter 31 captures impurities in the filtrate water filtered by the first filtration tank 20 that could not be captured by the first filter 21.

[0053] The second filtration tank 30 is provided mainly for its filtering function, and does not have the function of temporarily storing filtered water, as the first filtration tank 20 does. Therefore, in the embodiment of the present invention, the volume of the second filtration tank 30 is smaller than that of the first filtration tank 20, but this is not limited thereto, and the volume of the second filtration tank 30 may be increased to temporarily store filtered water. Furthermore, the structure of the inner wall and outer wall of the second filtration tank 30 is similar to that of the first filtration tank 20, and detailed description thereof will be omitted here.

[0054] As shown in Fig. 6, a second filter 31 is installed in the second filtration tank 30 to further filter the filtered water sent from the first filtration tank 20. The second filter 31 is detachably fixed to the upper end of the second filtration tank 30 by a known joint 32 such as a prefabricated joint, making it easy to perform periodic replacement work.

[0055] The second filter 31 is filled with ion exchange resin, and by adsorbing salt components such as calcium, sodium, and chloride contained in the filtered water sent from the first filtration tank 20, it is possible to remove impurities that cannot be removed by the first filter 21 and produce highly pure water.

[0056] The filtration water passage P5 is composed of a first filtration water passage P5a that sends filtered water from the first filtration tank 20 to the second filtration tank 30, and a second filtration water passage P5b that sends filtered water from the second filtration tank 30 to the filtrate water storage tank 40. A valve V5 is provided in the first filtration water passage P5a, so that the amount of filtered water supplied from the first filtration tank 20 can be adjusted.

[0057] As described above, one end of the first filtration water passage 5a is connected to the first filter 21 in the first filtration tank 20 via the connecting pipe 24. The other end of the first filtration water passage 5b is disposed so as to face the inside of the second filtration tank 30 from the side surface of the second filtration tank 30.

[0058] The shape of the other end of the first filtration water channel P5a is the same as the shape of the end of the rain water channel P4 described above, with slits formed on the side of the end, and the filtered water sent from the first filtration tank 20 sprays out from the slits to form a rotating flow in the second filtration tank 30. This rotating flow increases the contact area of ​​the second filter 31, and the filtered water sent from the first filtration tank 20 can be reliably filtered by the second filter 31.

[0059] The filtered water filtered by the second filter 31 is sent to the filtered water storage tank 40 through a second filtered water passage P5b connected to the upper end of the second filtration tank 30. A valve V6 is provided at the bottom of the second filtration tank 30, and is always closed when the storm water treatment system 1 is in operation, and is opened when the residual water in the second filtration tank 30 is to be drained during replacement or maintenance of the second filter 31.

[0060] Here, the second filtration tank 30 does not necessarily have to be provided. For example, the filtered water filtered by the first filtration tank 20 may be directly supplied to the filtrate water storage tank 40. However, as described above, by performing two-stage filtration by the first filter 21 and the second filter 31, impurities that cannot be captured by the first filter 21 can be captured by the second filter 31, and therefore highly pure water can be produced.

[0061] [Filtered water storage tank] The filtrate water storage tank 40 is a storage tank for storing filtrate water filtered in the second filtration tank 30 (filtered water filtered in the first filtration tank 20 if the second filtration tank 30 is not installed), and in the embodiment of the present invention, is composed of a first filtrate water storage tank 40a and a second filtrate water storage tank 40b.

[0062] Here, the filtrate water storage tank 40 does not necessarily have to be composed of the first filtrate water storage tank 40a and the second filtrate water storage tank 40b. One filtrate water storage tank 40 or three or more filtrate water storage tanks 40 may be installed depending on the purpose.

[0063] The first filtrate water storage tank 40a is connected to the second filtrate water passage P5b, and is configured to constantly supply filtrate water filtered by the first filter 21 and the second filter 31. When the water level in the first filtrate water storage tank 40a rises to a certain level, the filtrate water passage P5 is completely shut off by the ball tap B to stop the supply of filtrate water, and when the water level drops, the filtrate water passage P5 is opened again to supply filtrate water.

[0064] Here, it is not necessary to adopt the ball tap B as the cutoff mechanism for the filtration water passage P5. For example, the cutoff and opening of the filtration water passage P5 may be controlled by controlling a float-type reed switch or an electrode rod.

[0065] The first filtrate water storage tank 40a and the second filtrate water storage tank 40b are connected by a communication passage P7, which is connected to a circulation passage P8 via a valve V7, and the circulation passage P8 is connected to a drainage passage P3. The valve V7 is normally closed, and filtered water is supplied from the first filtrate water storage tank 40a to the second filtrate water storage tank 40b. When the second filtrate water storage tank 40b becomes full, the valve V7 is opened, and a portion of the filtrate water is drained from the drainage passage P3 to the outside of the system via the circulation passage P8.

[0066] A water supply tap 41 for utilizing the stored filtered water is provided at a predetermined position on the side of the second filtered water storage tank 40b. Therefore, a user can utilize the filtered water supplied from the water supply tap 41 for various purposes, such as water for washing a car, watering plants, cleaning water, dry mist, or water for daily life in an emergency.

[0067] Here, it is not essential to have the filtrate water storage tank 40. For example, it is possible to take out the filtrate filtered in the first filtration tank 20 directly from the first filtration tank 20 and use it.

[0068] Moreover, the water supply tap 41 does not necessarily have to be installed only in the second filtrate water storage tank 40b, but may also be installed in the first filtrate water storage tank 40a.

[0069] [Example] Next, the results of a water quality test of filtered water when rainwater is treated using the rainwater treatment system 1 according to the embodiment of the present invention will be shown.

[0070] <Evaluation target> Water quality tests were conducted on the following four samples, A to D. A. Rainwater raw water B Rainwater in the first filter tank before filtration by the first filter C Filtrate after filtration through the first filter D Filtrate after filtration through the second filter

[0071] <Evaluation method> An external organization conducted water quality testing on the above four samples, A through D. The results are shown in Table 1.

[0072] [Table 1]

[0073] In Table 1, the increase in the amount of suspended matter deposition [SS] in sample B is due to the accumulation of heavy impurities contained in the rainwater at the bottom of the first filtration tank 20, and in the first filtration tank 20, heavy and light impurities are efficiently separated from the rainwater before filtration by the first filter 21.

[0074] Regarding turbidity, samples C and D had lower values ​​than samples A and B, indicating that the first filter 21 and the second filter 31 were able to produce filtered water with high transparency.

[0075] Concerning electrical conductivity, pure water generally has an electrical conductivity in the range of 0.05 to 1 (mS / m), but the electrical conductivity of not only Samples C and D but also Sample B is at the level of pure water. This also shows that in the first filtration tank 20, impurities with a high specific gravity and impurities with a low specific gravity can be efficiently separated from the rainwater before filtration by the first filter 21.

[0076] In addition, the total hardness of Samples C and D is lower than that of Samples A and B, and the chloride ion content of Samples C and D is also lower than that of Samples A and B. Therefore, the first filter 21 and the second filter 31 effectively capture metal ions and chloride ions contained in the rainwater, and highly pure water can be produced.

[0077] From the above results, it is possible to obtain highly pure water by treating rainwater with the rainwater treatment system 1.

[0078] As described above, according to the rainwater treatment system 1 of the present invention, no external power is required for each of the series of processes from supplying rainwater as the water to be treated to filtering the rainwater to produce filtered water. Therefore, even in the event of a disaster, rainwater can be treated to produce pure water with high purity.

[0079] In addition, by focusing on the specific gravity of impurities contained in rainwater, impurities heavier than the specific gravity of rainwater are deposited at the bottom of each tank, impurities with the same or lighter specific gravity as rainwater are captured by a filter, and impurities lighter than the specific gravity of rainwater that cannot be captured by the filter are discharged outside the system as overflow water.This makes it possible to produce highly pure water while preventing filter deterioration and achieving a system with low running costs.

[0080] As is clear from the above-described embodiment, the filtered water treated by the rainwater treatment system 1 is extremely pure water from which impurities such as mineral ions and metal ions generally found in large amounts in tap water, as well as sparingly soluble scale and other impurities, have been removed.

[0081] Therefore, for example, when the filtered water obtained by the rainwater treatment system 1 is used as water for washing a car, dirt adhering to the car body can be removed without damaging the paint film of the car body. Also, when the filtered water is used as dry mist for a cooled device such as an air conditioner, clogging or corrosion of the spray device, or adhesion of scale to the cooled device can be prevented.

[0082] As described above, the rainwater treatment system and rainwater treatment method according to the present invention can remove impurities from rainwater and produce pure water at low cost without requiring external power. [Explanation of symbols]

[0083] 1. Stormwater treatment system 10 Rainwater storage tank 20 1st filtration tank 21 First Filter 22, 23 Bracket 24 Connecting pipe 25 Inspection cover 30 Second filtration tank 31 Second Filter 32 Joint 40 Filtrate water storage tank 40a First filtered water storage tank 40b Second filtrate water storage tank 41 Water Tap B Ball tap P1 downpipe path P2 Branch Road P3 drainage canal P4 Rain channel P5 Filtration waterway P5a 1st filtration waterway P5b 2nd filtration waterway P6 Overflow Channel P7 communication path P8 circulation path S slit hole V1, V2, V3, V4, V5, V6, V7 Valves

Claims

1. a cylindrical first filtration tank in which a first filter for filtering the rainwater that flows in is housed and extends vertically so as to form a predetermined gap between the first filter and an inner wall of the tank; a rainwater channel connected to the upper part of the first filtration tank, the end facing the inside of the first filtration tank being closed and a slit hole being formed along the circumferential direction of the side surface near the end, and the rainwater flowing in is jetted from the slit hole toward the inner wall of the first filtration tank so that the rainwater turns into a rotating flow rotating around the vertical axis of the first filter of the first filtration tank and flows vertically downward along the inner wall of the first filtration tank; an overflow waterway for draining overflow water from the first filtration tank when the water level in the first filtration tank exceeds a predetermined water level; a drainage channel connected to the overflow channel for draining the overflow water to the outside of the system; a cylindrical second filtration tank in which a second filter for further filtering the filtered water sent from the first filtration tank is installed so as to extend vertically so as to form a predetermined gap between the second filter and an inner wall of the second filtration tank; a filtration water channel having one end connected to a lower portion of the first filtration tank and the other end connected to the second filtration tank, an end facing the inside of the second filtration tank being closed and a slit hole being formed along the circumferential direction of the side surface near the end, and the filtrate water sent from the first filtration tank being sprayed from the slit hole so as to become a rotating flow and flow along the inner wall of the second filtration tank. Stormwater treatment system.

2. A filtrate storage tank for storing the filtrate filtered by the first filtration tank. The storm water treatment system according to claim 1.

3. The bottom of the first filtration tank has an openable and closable valve for draining impurities, which are relatively heavy in specific gravity and are contained in rainwater, out of the system. The storm water treatment system according to claim 1 or 2.

4. The upper part of the first filtration tank has an inspection cover for opening and closing an inspection hatch for inspecting the internal condition. The storm water treatment system according to claim 1 or 2.

5. The rainwater channel is provided with a rainwater storage tank for temporarily storing rainwater, Rainwater overflowing from the rainwater storage tank flows into the first filtration tank. The storm water treatment system according to claim 1 or 2.

6. The bottom of the rainwater storage tank has an openable and closable valve for draining impurities, which are relatively heavy in specific gravity and contained in the rainwater, out of the system. The storm water treatment system according to claim 5.

7. The first filtration tank and the second filtration tank have inner walls made of resin material and outer walls made of insulating material. The storm water treatment system according to claim 1.

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