Water treatment system and method

Abstract

To purify raw water such as rainwater using a reverse osmosis membrane or the like, while providing a required amount of treated water at a required time.SOLUTION: A water treatment system includes: a raw water storage tank for storing raw water; first water conveyance means for conveying the raw water stored in the raw water storage tank; a reverse osmosis membrane for separating the conveyed raw water into permeated water and concentrated water; an activated carbon filter for filtering the permeated water; and a treated water storage tank for adding chlorine to water that has passed through the activated carbon filter, and storing the treated water.SELECTED DRAWING: Figure 1

Description

【Technical Field】 【0001】 The present disclosure relates to a water treatment system and method. 【Background Art】 【0002】 A water purification device has been proposed that produces drinking water with residual chlorine within a standard range from raw water such as that in a school pool (see Patent Document 1). 【0003】 The purification device described in Patent Document 1 sucks up raw water by a reciprocating manual pump and purifies and supplies the sucked-up raw water. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Unexamined Patent Application Publication No. 2018 - 176088 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 In Patent Document 1, a reverse osmosis membrane is used, but purification using a reverse osmosis membrane takes time and is not suitable when a predetermined amount is desired to be used immediately. 【0006】 An object of the present disclosure is to provide a necessary amount of treated water at a necessary timing while purifying raw water such as rainwater using a reverse osmosis membrane or the like. 【Means for Solving the Problems】 【0007】 A water treatment system including a raw water storage tank for storing raw water, a first water supply means for supplying the raw water stored in the raw water storage tank, a reverse osmosis membrane for separating the supplied raw water into permeate water and concentrated water, an activated carbon filter for filtering the permeate water, and a treated water storage tank for adding chlorine to and storing the water that has passed through the activated carbon filter. 【Effects of the Invention】 【0008】 According to this disclosure, raw water such as rainwater can be purified using reverse osmosis membranes, etc., and the required amount of treated water can be provided at the required time. [Brief explanation of the drawing] 【0009】 [Figure 1] This is a block diagram showing an example of the system configuration according to this embodiment. [Figure 2] This flowchart shows an example of the operation of the control device 36 when purifying the raw water stored in the raw water storage tank 21. [Figure 3] This flowchart shows an example of the operation of the control device 36 when the treated water stored in the treated water storage tank 31 is sent to the raw water storage tank 21. [Figure 4] This graph shows the changes in TOC and TN with and without the activated carbon filter 18 installed. [Figure 5] This block diagram shows other configuration examples of the system according to this embodiment. [Figure 6] This flowchart shows another example of the operation of the control device 36 when the treated water stored in the treated water storage tank 31 is sent to the raw water storage tank 21. [Figure 7] This flowchart shows another example of the operation of the control device 36 when purifying the raw water stored in the raw water storage tank 21. [Figure 8] A block diagram showing the basic hardware configuration of Computer 90. [Modes for carrying out the invention] 【0010】 Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. In the drawings used to illustrate the embodiment, the same reference numerals are generally used for identical components, and repeated descriptions thereof will be omitted. 【0011】 <Overview> The system according to this embodiment is a system that uses treated water, obtained by filtering raw water such as rainwater, surface water, or groundwater, as drinking water or domestic water. In this embodiment, drinking water may include, for example, water used for washing the face, cooking, etc. In this embodiment, domestic water refers to water used in daily life, such as for bathing, showering, washing clothes, washing dishes, etc. The system separates the raw water stored in the raw water storage tank into permeate and concentrated water using a reverse osmosis membrane. The system supplies the permeate to the treated water storage tank after passing it through an activated carbon filter. Chlorine is added to the treated water storage tank to suppress the growth of bacteria. The system measures the chlorine concentration in the treated water storage tank, and if it does not reach a predetermined value, it returns the water from the treated water storage tank to the raw water storage tank. 【0012】 <System Configuration> The overall configuration of System 1 according to this embodiment will be described below. 【0013】 Figure 1 is a block diagram showing an example configuration of the system according to this embodiment. In Figure 1, the system 1 is installed, for example, inside, outside, or both of the building 100. The outside of the building 100 includes, for example, the basement of the building 100. Also, a part of the system 1 may be buried underground. In Figure 1, the example is given where the raw water is rainwater taken in by the building 100, but the raw water is not limited to rainwater. 【0014】 The building 100 is equipped with, for example, a rain gutter 101 and a debris filter 102. Rain that falls on the building 100 is collected through the rain gutter 101, and debris is removed by the debris filter 102 before the water is taken in. 【0015】 Inside the building 100, for example, a raw water storage tank 21 is installed. Note that the raw water storage tank 21 may be installed outside the building 100. The raw water storage tank 21 is a tank for storing the supplied raw water. The raw water storage tank 21 has a capacity, for example, to store raw water that enables a family of several people to live for several days. Rainwater taken in through a rain gutter 101 and a trash screen 102 is supplied to the raw water storage tank 21. Also, water sent out by a pump 24 is supplied to the raw water storage tank 21. 【0016】 In the raw water storage tank 21, for example, an ozone generator 22 is installed. The ozone generator 22 generates ozone gas, for example, for sterilizing the water in the raw water storage tank 21. The ozone generator 22 supplies the generated ozone gas to the raw water storage tank 21. Specifically, the ozone generator 22 supplies ozone gas to the raw water in the raw water storage tank 21, that is, to the liquid phase of the raw water storage tank 21. Note that the ozone generator 22 may also supply ozone gas to the gas phase of the raw water storage tank 21. 【0017】 Examples of the method for generating ozone gas by the ozone generator 22 include a discharge method (silent discharge method), an electrolysis method (water electrolysis cell method), an ultraviolet method (mercury UV lamp method, mercury-free UV lamp (excimer lamp) method), etc. Among these, the ultraviolet method (mercury-free UV lamp (excimer lamp) method) is preferable. The ultraviolet method (mercury-free UV lamp (excimer lamp) method) can generate ozone gas with few impurities without generating harmful nitrogen oxides from nitrogen present in the atmosphere during ozone gas generation. Therefore, it is particularly suitable as a method to be adopted for an ozone generator installed in a small system such as a home. 【0018】 By generating ozone gas with few impurities, the operating time of the ozone generator 22 can be reduced, power consumption can be suppressed, and the ozone generator 22 can be made to have a longer lifespan. By generating ozone gas with few impurities, miniaturization of the system equipment and reduction of deterioration / damage locations are possible, which also leads to a reduction in maintenance frequency. 【0019】 A water level gauge (not shown) is installed in the raw water storage tank 21. The water level gauge detects the water level in the raw water storage tank 21 by measuring, for example, the potential. For example, when a predetermined first water level is detected by the water level gauge, the drain is opened and the treated water in the raw water storage tank 21 is discharged. When the water level reaches a predetermined second water level, the drain is closed. 【0020】 A pump 23 is attached to the pipe connected to the raw water storage tank 21. The pump 23 is driven under the control of the control device 36 of the system 1, and sends the raw water stored in the raw water storage tank 21 to the membrane treatment module 10. 【0021】 The membrane treatment module 10 is a self - contained membrane treatment module and can be installed in various places such as indoors and outdoors. Specifically, for example, a plurality of filter cartridges in the membrane treatment module 10 are attached so that they can be replaced. The membrane treatment module 10 is arranged indoors in the building 100, for example, so that a user can replace a filter cartridge that has reached its expiration date while staying inside the building 100. Also, when there is no space inside the building 100, the membrane treatment module 10 may be arranged outdoors. The membrane treatment module 10 may have a moving mechanism such as wheels and may be configured to be movable. In this case, even if the membrane treatment module 10 is once arranged at a predetermined position, its arrangement can be changed at an arbitrary timing. 【0022】 The membrane treatment module 10 includes a conductivity sensor 11, a pressure sensor 12, a first filter 13, a sensor group 15, a reverse osmosis membrane 16, a sensor group 17, an activated carbon filter 18, a valve 19, and a drain water storage tank 110. Note that the configuration of the membrane treatment module 10 is not limited to these. For example, the membrane treatment module 10 may include devices other than these, or may not include any of these devices. 【0023】 The conductivity sensor 11 detects the electrical conductivity of the water discharged from the pump 23 and supplied to the membrane processing module 10. The pressure sensor 12 detects the pressure of the water discharged from the pump 23 and supplied to the membrane processing module 10. 【0024】 The first filter 13 removes, for example, solids and / or water pollutants from the water sent from the pump 23. In this embodiment, a wound filter is used as the first filter 13, but it is not limited to this. For example, at least one of the following may be selected: a sediment filter, MF (microfiltration membrane), UF (ultrafiltration membrane), NF (nanofiltration membrane), ceramic filter, ion exchange filter, or metal membrane. 【0025】 The sensor group 15 is positioned upstream of the reverse osmosis membrane 16. The sensor group 15 detects the components or physical properties of the water supplied to the reverse osmosis membrane 16. In the illustrated example, the sensor group 15 includes a pressure sensor, a flow sensor, and a conductivity sensor. 【0026】 The pressure sensor detects the pressure of the water supplied to the reverse osmosis membrane 16. The flow rate sensor detects the flow rate of the water supplied to the reverse osmosis membrane 16. The conductivity sensor detects the electrical conductivity of the water supplied to the reverse osmosis membrane 16. 【0027】 In addition to the sensors described above, the sensor group 15 may also include sensors that sense at least one of the following: (1) pH, oxidation-reduction potential, alkalinity, ion concentration, hardness (2) Turbidity, color, viscosity, dissolved oxygen (3) Odors, ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, total nitrogen, residual chlorine, total phosphorus, total organic carbon, total inorganic carbon, total trihalomethanes (4) Microbial sensor detection results, chemical oxygen demand, biological oxygen demand, (5) Cyanide, mercury, oil, surfactants (6) Detection results from optical sensors and TDS (Total Dissolved Solids) sensors (7) Mass spectrometry results, fine particles, zeta potential, surface potential 【0028】 The reverse osmosis membrane 16 separates the supplied water into permeate from which dissolved components have been removed and concentrated water from which dissolved components have been concentrated. The reverse osmosis membrane 16 is implemented, for example, by a spiral-type reverse osmosis membrane. The reverse osmosis membrane 16 is an example of a cross-flow type filtration membrane. A cross-flow type filtration membrane is a filtration membrane that performs filtration while suppressing the accumulation of suspended solids and colloids in the wastewater supplied to the membrane by creating a flow parallel to the membrane surface. In other words, a cross-flow type filtration membrane is a membrane that performs filtration by pumping wastewater at a pressure higher than the osmotic pressure of the membrane. As such a cross-flow type filtration membrane, a nanofiltration membrane (NF membrane), an ultrafiltration membrane (UF membrane), or a microfiltration membrane (MF membrane) may be used instead of a reverse osmosis membrane. The permeate separated by the reverse osmosis membrane 16 is supplied to the sensor group 17. The concentrated water separated by the reverse osmosis membrane 16 is discharged to the wastewater storage tank 110 via the valve 19. The concentrated water stored in the wastewater storage tank 110 is used, for example, for flushing toilets, emergency water, and laundry. The wastewater storage tank 110 may also be called, for example, a wastewater storage tank for domestic wastewater. 【0029】 The sensor group 17 is positioned downstream of the reverse osmosis membrane 16. The sensor group 17 detects the components or physical properties of the permeate separated by the reverse osmosis membrane 16. In the illustrated example, the sensor group 17 includes a conductivity sensor, a flow sensor, and a pressure sensor. 【0030】 The conductivity sensor detects the electrical conductivity of the permeate separated by the reverse osmosis membrane 16. The pressure sensor detects the pressure of the permeate separated by the reverse osmosis membrane 16. The flow rate sensor detects the flow rate of the permeate separated by the reverse osmosis membrane 16. 【0031】 In addition to the sensors described above, the sensor group 17 may also include sensors that sense at least one of (1) to (7) shown in sensor group 15. 【0032】 Immediately after the reverse osmosis membrane 16 is activated, the permeate is measured by the sensor group 17 and then supplied to the wastewater storage tank 110 until predetermined requirements are met. For example, a predetermined valve is installed to switch the flow path. The predetermined requirements include, for example, that the water quality of the permeate stabilizes (for example, that the value of the conductivity sensor of sensor group 17 stabilizes), or that the value of the conductivity sensor of sensor group 17 becomes smaller than the value of the conductivity sensor of sensor group 15. 【0033】 The activated carbon filter 18 is located, for example, downstream from the reverse osmosis membrane 16 via the sensor group 17. The activated carbon filter 18 removes organic matter that may be present in the permeate discharged from the reverse osmosis membrane 16. Due to the creep phenomenon of the reverse osmosis membrane 16, organic matter may be mixed into the permeate supplied from the reverse osmosis membrane 16. The activated carbon filter 18 prevents organic matter that may be present in the permeate from reaching the treated water storage tank 31. The water that has passed through the activated carbon filter 18 is discharged into the treated water storage tank 31. 【0034】 Information detected by the conductivity sensor 11, pressure sensor 12, sensor group 15, and sensor group 17 is stored in a memory unit (not shown) installed in the film processing module 10. The information stored in the memory unit is output in response to a predetermined request. The output of information may be performed via a medium attached to a predetermined interface, or it may be performed by a communication unit (not shown) installed in the film processing module 10 in accordance with a predetermined protocol. The output of information may be performed in response to instructions from the user, or it may be performed automatically at a predetermined interval. 【0035】 The treated water storage tank 31 is installed, for example, indoors in building 100. The treated water storage tank 31 may also be installed outdoors in building 100. The treated water storage tank 31 is a tank for storing the supplied treated water. The treated water storage tank 31 has a capacity to store enough treated water for a family of several people to live on for several days, for example. The treated water storage tank 31 may have a capacity similar to that of the raw water storage tank 21. Treated water that has passed through the activated carbon filter 18 is supplied to the treated water storage tank 31. 【0036】 A chlorine meter 32 is installed in the treated water storage tank 31. The chlorine meter 32 measures the residual chlorine concentration in the treated water stored in the treated water storage tank 31. The residual chlorine concentration gradually decreases over time after the supply of chlorine-based chemicals (hereinafter referred to as chlorinated water). Chlorine-based chemicals are disinfectants such as sodium hypochlorite or hypochlorous acid water. 【0037】 Chlorinated water is supplied to the treated water storage tank 31 from the chlorine supply unit 33. The chlorine supply unit 33 is implemented, for example, by a chlorine tank and a chlorine pump. The chlorine tank is a tank for storing chlorinated water. Chlorinated water is produced, for example, by dissolving hypochlorous acid tablets in water supplied to the chlorine tank. Alternatively, chlorinated water may be produced by dissolving salt in water supplied to the chlorine tank and electrolyzing the resulting saline solution. An electrolysis unit that performs electrolysis on saline solution to produce chlorinated water may be provided separately downstream of the chlorine tank. 【0038】 The chlorine pump is driven by the control device 36 and adds chlorinated water stored in the chlorine tank to the treated water storage tank 31. Specifically, for example, the control device 36 drives the chlorine pump so that the residual chlorine concentration in the treated water storage tank 31 in the initial period after purification exceeds a predetermined value. This can be rephrased as the control device 36 adding a preset amount of chlorinated water to the treated water storage tank 31 in the initial period after purification. The predetermined value is set to 1 ppm, for example, based on the drinking water quality standard value of 0.1 ppm. However, the predetermined value is not limited to 1 ppm and may be other values. For example, the predetermined value may be 2 ppm. Furthermore, when the control device 36 drives the pump 24 to circulate the treated water stored in the treated water storage tank 31 through the raw water storage tank 21 and stores it in the treated water storage tank 31, the control device 36 drives the chlorine pump so that the residual chlorine concentration in the treated water storage tank 31 after circulation exceeds a predetermined value. This can be rephrased as the control device 36 adding a preset amount of chlorinated water to the treated water storage tank 31 after circulation. 【0039】 Furthermore, the chlorinated water may be added to the treated water after it has passed through the activated carbon filter 18, rather than being added directly to the treated water storage tank 31. In this case, the treated water to which the chlorinated water has been added is supplied to the treated water storage tank 31. 【0040】 A water level gauge (not shown) is installed in the treated water storage tank 31. The water level gauge detects the water level in the treated water storage tank 31, for example, by measuring the electric potential. For example, when a predetermined first water level is detected by the water level gauge, the drain is opened and the treated water in the treated water storage tank 31 is discharged, and when the water level reaches a predetermined second water level, the drain is closed. 【0041】 The treated water storage tank 31 is connected to piping for supplying treated water to consumers living in building 100. A pump 34 is attached to this piping. The pump 34 is driven by the control device 36 and supplies the treated water stored in the treated water storage tank 31 to consumers living in building 100. Specifically, for example, when the control device 36 detects a request signal for treated water from consumers in building 100, it drives the pump 34. An example of a request signal for treated water from a consumer is as follows: • Requests for the supply of treated water to the treated water outlet (e.g., turning on the faucet, approaching an infrared sensor installed at the outlet, etc.) • Operation requests for devices such as washing machines, bathtubs, toilets, and dishwashers (e.g., button presses). • Requests for the supply of treated water based on scheduled operation for devices such as washing machines and bathtubs. 【0042】 The UV sterilization unit 35 is located between the treated water storage tank 31 and the pump 34. The UV sterilization unit 35 sterilizes the treated water drawn in from the treated water storage tank 31 by irradiating it with ultraviolet light. The treated water that has passed through the UV sterilization unit 35 is supplied to the customer. 【0043】 Sensor 37 is installed downstream of pump 34. Sensor 37 detects whether or not water has been supplied to the customer. Specifically, sensor 37 is implemented by, for example, a capacitive sensor that detects the capacitance in the piping. When pump 34 is driven and treated water is supplied to the customer, sensor 37 detects that water has been supplied to the customer based on the change in capacitance. Note that sensor 37 may be installed at the customer's drain outlet rather than between pump 34 and the customer. A filter for removing predetermined components may be installed between pump 34 and the customer. 【0044】 A piping system is connected between the treated water storage tank 31 and the raw water storage tank 21 to supply the treated water stored in the treated water storage tank 31 to the raw water storage tank 21. A pump 24 is attached to this piping. The pump 24 is driven by the control device 36 and supplies the treated water stored in the treated water storage tank 31 to the raw water storage tank 21. The control device 36 drives the pump 24, for example, when the residual chlorine concentration measured by the chlorine meter 32 is below a predetermined threshold. The control device 36 also drives the pump 24 when the amount of water in the treated water storage tank 31 falls below a predetermined amount. The predetermined amount may, for example, represent the point at which the treated water storage tank 31 is almost empty of treated water. Specifically, for example, the control device 36 drives the pump 24 when the water level in the treated water storage tank 31 reaches a predetermined level. 【0045】 The control device 36 may, for example, drive the pump 24 until the raw water storage tank 21 is full. Alternatively, the control device 36 may drive the pump 24 until the treated water storage tank 31 reaches a predetermined water level. This predetermined water level may include a water level of approximately zero. The control device 36 may also drive the pump 24 to send a predetermined volume of treated water stored in the treated water storage tank 31 to the raw water storage tank 21. 【0046】 When the treated water from the treated water storage tank 31 is supplied to the raw water storage tank 21 and the raw water storage tank 21 becomes full, the excess water supplied from the treated water storage tank 31 is used, for example, outdoors. Specifically, the excess water is used, for example, for washing and cleaning household appliances, watering garden trees, sprinkling water, watering biotopes, and landscaping. When the treated water from the treated water storage tank 31 is supplied to the raw water storage tank 21 and the raw water storage tank 21 becomes full, the control device 36 drives the pump 23, for example, to purify the raw water in the raw water storage tank 21. Alternatively, when the treated water from the treated water storage tank 31 is supplied to the raw water storage tank 21 and the raw water storage tank 21 becomes full, the control device 36 may stop the pump 24 and release the raw water stored in the raw water storage tank 21 by opening the drain of the raw water storage tank 21. After the control device 36 has discharged the raw water from the raw water storage tank 21, it restarts the pump 24 and supplies the treated water from the treated water storage tank 31 to the raw water storage tank 21. If the raw water storage tank 21 becomes full due to the supply of treated water from the treated water storage tank 31, the control device 36 may stop the pump 24 and open the drain of the treated water storage tank 31. 【0047】 The control device 36 is implemented by the processor reading a program stored in storage, expanding it into memory, and executing the instructions contained in the expanded program. The processor is hardware for executing the instruction set written in the program, and consists of an arithmetic unit, registers, peripheral circuits, etc. Storage is a memory device for saving data, such as flash memory or an HDD (Hard Disk Drive). Memory is for temporarily storing programs and data processed by programs, etc., and is a volatile memory such as DRAM (Dynamic Random Access Memory). 【0048】 The control device 36 controls, for example, the operation of pumps 23, 24, and 34. The control device 36 also controls, for example, the operation of the chlorine pump in the chlorine supply unit 33. 【0049】 <Operation> The control process in System 1 will be described below. 【0050】 (Purification of raw water) Figure 2 is a flowchart showing an example of the operation of the control device 36 when purifying raw water stored in the raw water storage tank 21. The control device 36 performs the process shown in Figure 2, for example, when purifying raw water for the first time after starting the system 1, or when purifying raw water after moving the treated water from the treated water storage tank 31 to the raw water storage tank 21. For example, rainwater is stored in the raw water storage tank 21. The control device 36, for example, drives the ozone generator 22 at a predetermined timing to sterilize the raw water in the raw water storage tank 21 with ozone. 【0051】 Specifically, in step S11, the control device 36 drives the pump 23. Specifically, for example, the control device 36 drives the pump 23 in response to instructions from the user. The user, for example, confirms that a sufficient amount of raw water has accumulated in the raw water storage tank 21 and instructs the start of raw water purification. The user's instruction may be a reservation to start purification, which will be executed on the condition that the raw water has accumulated to a predetermined level. Alternatively, the user may, for example, confirm that the treated water in the treated water storage tank 31 has reached a predetermined level and instruct the start of raw water purification. The user's instruction may be a reservation to start purification, which will be executed on the condition that the treated water in the treated water storage tank 31 has reached a predetermined level. 【0052】 When the pump 23 is driven, raw water is supplied from the raw water storage tank 21 to the membrane treatment module 10. The membrane treatment module 10 removes, for example, solids and / or water pollutants contained in the raw water using the first filter 13. The membrane treatment module 10 separates the water treated by the first filter 13 into permeate and concentrated water using the reverse osmosis membrane 16. The membrane treatment module 10 removes organic matter contained in the permeate separated by the reverse osmosis membrane 16 using the activated carbon filter 18. The membrane treatment module 10 supplies the purified water to the treated water storage tank 31. 【0053】 In step S12, the control device 36 determines whether the water level in the treated water storage tank 31 has reached a predetermined value. Specifically, for example, a water level gauge is installed in the treated water storage tank 31 at a position where a predetermined water level can be detected. When the water level in the treated water storage tank 31 reaches the predetermined water level, the water level gauge transmits a detection signal to the control device 36. Upon receiving the detection signal, the control device 36 determines that the water level in the treated water storage tank 31 has reached a predetermined value. If the control device 36 determines that the water level in the treated water storage tank 31 has reached a predetermined value, it proceeds to step S13. If the control device 36 does not determine that the water level in the treated water storage tank 31 has reached a predetermined value, it proceeds to step S11 and maintains the operation of the pump 23. 【0054】 In step S13, the control device 36 stops the pump 23. As a result, the control device 36 continuously purifies the raw water until a predetermined amount of treated water is stored in the treated water storage tank 31, and stores the treated water in the treated water storage tank 31. At a predetermined timing, the raw water in the raw water storage tank 21 is purified all at once until the treated water storage tank 31 is nearly full, which reduces the operation of the pump and makes it possible to reduce the amount of electricity used. 【0055】 In step S14, the control device 36 drives the chlorine supply unit 33. Specifically, the control device 36 drives the chlorine pump of the chlorine supply unit 33. When driven by the control device 36, the chlorine pump adds the chlorinated water stored in the chlorine tank to the treated water storage tank 31. 【0056】 In step S15, the control device 36 determines whether the residual chlorine concentration in the treated water storage tank 31 has reached a predetermined value. Specifically, for example, the chlorine meter 32 measures the residual chlorine concentration of the treated water stored in the treated water storage tank 31 and transmits the measurement result to the control device 36. The control device 36 refers to the measurement result transmitted from the chlorine meter 32 and determines whether the residual chlorine concentration in the treated water storage tank 31 has reached a predetermined value, for example, 1 ppm based on the drinking water quality standard value of 0.1 ppm. If the residual chlorine concentration in the treated water storage tank 31 has reached the predetermined value, the control device 36 moves the process to step S16. If the residual chlorine concentration in the treated water storage tank 31 has not reached the predetermined value, the control device 36 moves the process to step S14 and maintains the operation of the chlorine pump. 【0057】 In step S15, the control device 36 may determine whether or not a preset amount of chlorinated water has been added to the treated water storage tank 31. If a preset amount of chlorinated water has been added to the treated water storage tank 31, the control device 36 proceeds to step S16. If a preset amount of chlorinated water has not been added to the treated water storage tank 31, the control device 36 proceeds to step S14 and maintains the operation of the chlorine pump. 【0058】 In step S16, the control device 36 stops the chlorine pump. As a result, the control device 36 ensures that the residual chlorine concentration of the treated water stored in the treated water storage tank 31 reaches a predetermined value. 【0059】 In the explanation in Figure 2, the control device 36 stops the pump 23 in step S13 and then drives the chlorine pump in step S14. However, the control device 36 may perform an operation other than step S14 after stopping the pump 23 in step S13. For example, after stopping the pump 23 in step S13, the control device 36 may measure the residual chlorine concentration of the circulated treated water stored in the treated water storage tank 31 using the chlorine meter 32. For example, if the residual chlorine concentration measured at this time is less than, for example, 0.1 ppm, which is the drinking water quality standard value, the control device 36 will determine that an abnormality has occurred and will stop all operations of system 1. When the control device 36 determines that an abnormality has occurred, it stores the sensing data measured by the membrane treatment module 10 as data at the time of the abnormality. 【0060】 (Circulation process) Figure 3 is a flowchart showing an example of the operation of the control device 36 when sending treated water stored in the treated water storage tank 31 to the raw water storage tank 21. For example, in System 1, the control device 36 executes the process shown in Figure 3 when sufficient treated water is stored in the treated water storage tank 31 and the system is in a normal operating state. 【0061】 In step S31, the control device 36 stops the pump 24. 【0062】 In step S32, the control device 36 determines whether the residual chlorine concentration of the treated water in the treated water storage tank 31 is below a predetermined value. The residual chlorine concentration of the treated water in the treated water storage tank 31 decreases over time and due to other environmental factors. In this embodiment, under normal environmental conditions, the residual chlorine concentration is set not to fall below a predetermined value even after a predetermined period of time has elapsed. When the chlorine meter 32 detects that the residual chlorine concentration is below a predetermined value, the control device 36 moves the process to step S33. If the residual chlorine concentration is above a predetermined value, the control device 36 moves the process to step S34. The chlorine meter 32 measures the residual chlorine concentration at a predetermined interval, for example, once a day. 【0063】 In step S33, the control device 36 drives the pump 24. The pump 24 draws treated water from the treated water storage tank 31 and sends the drawn treated water to the raw water storage tank 21. When the pump 24 is driven, the control device 36 moves the process to step S36. 【0064】 In step S34, the control device 36 determines whether the water level of the treated water in the treated water storage tank 31 has reached a predetermined value. In other words, the control device 36 determines whether the amount of treated water in the treated water storage tank 31 has reached a predetermined amount. Specifically, for example, a water level gauge is installed in the treated water storage tank 31 at a position where a predetermined water level (a water level indicating that the water has almost run out) can be detected. When the water level in the treated water storage tank 31 reaches the predetermined water level, the water level gauge transmits a detection signal to the control device 36. Upon receiving the detection signal, the control device 36 determines that the water level in the treated water storage tank 31 has reached a predetermined value. If the control device 36 determines that the water level in the treated water storage tank 31 has reached a predetermined value, it proceeds to step S35. If the control device 36 does not determine that the water level in the treated water storage tank 31 has reached a predetermined value, it proceeds to step S31 and maintains the stop of the pump 24. 【0065】 In step S35, the control device 36 drives the pump 24. When driven, the pump 24 draws treated water from the treated water storage tank 31 and sends the drawn treated water to the raw water storage tank 21. When the pump 24 is driven, the control device 36 moves the process to step S36. 【0066】 In step S36, the control device 36 determines whether the water level of the treated water in the treated water storage tank 31 has reached a predetermined value. Specifically, when the pump 24 is driven, the treated water in the treated water storage tank 31 is sucked in, so the water level of the treated water in the treated water storage tank 31 decreases. The water level gauge of the treated water storage tank 31 detects when the treated water in the treated water storage tank 31 has reached a predetermined water level. The predetermined water level may be zero or any other level. When the water level gauge detects that the predetermined water level has been reached, it transmits a detection signal. Upon receiving the detection signal from the water level gauge, the control device 36 determines that the water level of the treated water in the treated water storage tank 31 has reached a predetermined value, proceeds to step S31, and stops the pump 24. If there is no detection signal from the water level gauge, the control device 36 determines that the water level of the treated water in the treated water storage tank 31 has not reached a predetermined value, proceeds to step S35, and continues to drive the pump 24. 【0067】 As a result, treated water is supplied from the treated water storage tank 31 to the raw water storage tank 21 until the water level of the treated water in the treated water storage tank 31 reaches a predetermined value. If the raw water storage tank 21 becomes full due to the supply of treated water from the treated water storage tank 31 to the raw water storage tank 21, the control device 36 may stop the pump 24. In this case, the raw water stored in the raw water storage tank 21 may be released by opening the drain of the raw water storage tank 21, and then the pump 24 may be restarted to supply the treated water from the treated water storage tank 31 to the raw water storage tank 21. 【0068】 As described above, in the above embodiment, the raw water storage tank 21 stores raw water. The pump 23 sucks up the raw water stored in the raw water storage tank 21 and pumps it. The reverse osmosis membrane 16 separates the pumped raw water into permeate and concentrated water. The activated carbon filter 18 filters the permeate. The treated water storage tank 31 stores the water that has passed through the activated carbon filter 18 with added chlorine. As a result, treated water purified by the reverse osmosis membrane 16 and the activated carbon filter 18 is stored in the treated water storage tank 31 ahead of demand. 【0069】 Therefore, according to the above embodiment, raw water such as rainwater can be purified using a reverse osmosis membrane, and the necessary amount of treated water can be provided at the necessary time. 【0070】 Furthermore, by installing the activated carbon filter 18 downstream of the reverse osmosis membrane 16, it becomes possible to prevent organic matter generated by the creep phenomenon of the reverse osmosis membrane 16 from reaching the treated water storage tank 31. As a result, it becomes possible to reduce the amount of disinfectant (chlorine water) added to the treated water storage tank 31. This makes it possible to suppress the harmful effects of excessive disinfectant addition, such as an increase in salt concentration in the water circulation system (increase in Na salts derived from sodium hypochlorite) and the generation of by-products (chloroacetic acid, trihalomethanes, chloric acid, etc.). 【0071】 Figure 4 is a graph showing the changes in TOC (total organic carbon) and TN (total nitrogen) with and without the activated carbon filter 18 installed. The graph in Figure 4 shows the results of measuring the TOC and TN of treated water stored in the treated water storage tank 31 using a TOC / TN meter. In Figure 4, the horizontal axis represents the number of times the reverse osmosis membrane 16 is operated, and the vertical axis represents TOC and TN. In Figure 4, the solid line represents TOC when the activated carbon filter 18 is installed, the dashed line represents TN when the activated carbon filter 18 is installed, the dotted line represents TOC when the activated carbon filter 18 is not installed, and the double dotted line represents TN when the activated carbon filter 18 is not installed. 【0072】 As shown in Figure 4, the TOC and TN values ​​in the treated water stored in the treated water storage tank 31 differ depending on whether or not the activated carbon filter 18 is present. By installing the activated carbon filter 18 downstream of the reverse osmosis membrane 16, TOC and TN are removed, and the treated water stored in the treated water storage tank 31 has better water quality than when the activated carbon filter 18 is not installed. 【0073】 Furthermore, in the above embodiment, if the chlorine concentration of the water stored in the treated water storage tank 31 does not reach a predetermined concentration, the pump 24 sends the water stored in the treated water storage tank 31 to the raw water storage tank 21. In other words, when the chlorine concentration in the treated water storage tank 31 falls below the threshold, instead of adding disinfectants such as chlorinated water, the water is sent to the raw water storage tank 21 and purification by the membrane treatment module 10 is performed again. Water contamination due to chlorine deficiency can be almost completely purified by the circulation treatment. In addition, by adding a necessary and sufficient amount of chlorine after the treated water has been stored in the treated water storage tank 31, the amount of chlorine added (used) in the entire circulation system can be suppressed. This makes it possible to maintain good water quality while suppressing the amount of chlorine added. Furthermore, it becomes possible to suppress the increase in Na ion concentration derived from chlorine-based chemicals in the rainwater treatment system due to the addition of excessive chlorine-based chemicals with disinfectant effects. 【0074】 <Variation> In the above embodiment, the example described was one in which the reverse osmosis membrane 16 separates the raw water into permeate and concentrated water once when supplying treated water from the raw water storage tank 21 to the treated water storage tank 31. However, the treatment by the reverse osmosis membrane 16 when purifying the raw water sent from the raw water storage tank 21 and supplying it to the treated water storage tank 31 is not limited to just one step. For example, the required water quality differs depending on how the treated water will be used. As shown in Figure 5, depending on the required water quality, the permeate separated by the reverse osmosis membrane 16 may be passed through the reverse osmosis membrane 16 again. More specifically, for example, when the treated water is used as drinking water, the separation by the reverse osmosis membrane 16 is performed once. On the other hand, when the treated water is used as drinking water, it is necessary to further improve the water quality. Therefore, when the treated water is used as drinking water, the permeate separated by the reverse osmosis membrane 16 is returned to the reverse osmosis membrane 16 a set number of times, and the separation treatment is repeated to improve the water quality of the permeate. Furthermore, the number of processing cycles in the reverse osmosis membrane 16 may be three or more, and is not limited to two cycles. In addition, the processing by the reverse osmosis membrane 16 may be repeated based on predetermined sensing data, not limited to a predetermined number of cycles. 【0075】 Furthermore, the above embodiment was described using the example of a case where only one treated water storage tank 31 is installed. However, the number of treated water storage tanks 31 installed in System 1 is not limited to one. Separate treated water storage tanks 31 may be installed depending on the intended use, such as drinking water or domestic water. Specifically, there may be a treated water storage tank for storing drinking water and a treated water storage tank for storing domestic water. 【0076】 Furthermore, the above embodiment was described using the example of a case where the circulation treatment is performed based on the residual chlorine concentration detected by the chlorine meter 32. However, the circulation treatment is not limited to one based on residual chlorine concentration. For example, if chlorinated water is added so that the residual chlorine concentration in the treated water storage tank 31 in the initial period after purification exceeds a predetermined value, under typical conditions, the residual chlorine concentration is set not to fall below a predetermined threshold for a predetermined period. In this embodiment, the predetermined threshold refers to, for example, 0.1 ppm, which is the standard value for tap water quality. The predetermined value is, for example, 1 ppm, which is set based on 0.1 ppm. In this case, the predetermined period can be set to, for example, one week (7 days). The control device 36 drives the pump 24 when, for example, the predetermined period has elapsed. 【0077】 Figure 6 is a flowchart showing another example of the operation of the control device 36 when the treated water stored in the treated water storage tank 31 is sent to the raw water storage tank 21. In Figure 6, the same reference numerals are used for the same processes as in Figure 3. 【0078】 In step S41, the control device 36 determines whether a predetermined period has elapsed. The target value of the residual chlorine concentration to be achieved by adding chlorinated water and the predetermined period are set based on a threshold value for the residual chlorine concentration. In other words, under normal conditions, if the residual chlorine concentration reaches the target value by adding chlorinated water, the system is set so that the residual chlorine concentration does not fall below the threshold value even after the predetermined period has elapsed. Therefore, by purifying the treated water stored in the treated water storage tank 31 with the membrane treatment module 10 at predetermined intervals, the treated water will be kept clean. 【0079】 The control device 36 determines whether a predetermined period has elapsed since the treated water was sent from the treated water storage tank 31 to the raw water storage tank 21 at the previous timing. In this embodiment, the predetermined period is, for example, 7 days. If the predetermined period has elapsed, the control device 36 moves the process to step S33. If the predetermined period has not elapsed, the control device 36 moves the process to step S31 and maintains the stop of the pump 24. 【0080】 Furthermore, in the above embodiment, the example described was that the purification of raw water stored in the raw water storage tank 21 is performed when the raw water storage tank 21 is full or when the amount stored in the treated water storage tank 31 becomes low. However, the timing of the purification of raw water is not limited to these. The control device 36 may also drive the pump 23 to purify the raw water when the treated water in the treated water storage tank 31 is used. Specifically, for example, the control device 36 may drive the pump 23 when it detects that the treated water stored in the treated water storage tank 31 has been supplied to a customer living in the building 100. 【0081】 Figure 7 is a flowchart illustrating another example of the operation of the control device 36 when purifying the raw water stored in the raw water storage tank 21. Figure 7 shows the operation when the raw water stored in the raw water storage tank 21 is purified by the membrane treatment module 10, depending on the use of the treated water stored in the treated water storage tank 31. For example, in system 1, the control device 36 executes the process shown in Figure 7 when there is sufficient treated water stored in the treated water storage tank 31 and the system is operating under normal conditions. 【0082】 In step S21, the control device 36 stops the pump 23. 【0083】 In step S22, the control device 36 determines whether or not water has been detected by the sensor 37. Specifically, for example, an infrared sensor is installed at the water outlet installed in the building 100. When a customer uses water, they approach the water outlet and allow the infrared sensor to detect them. When the infrared sensor detects the customer, it transmits a detection signal to the control device 36. Upon receiving the detection signal, the control device 36 determines that there has been a request signal from the customer. Upon receiving the detection signal, the control device 36 drives the pump 34. When driven by the control device 36, the pump 34 draws treated water from the treated water storage tank 31 via the UV sterilization unit 35. The pump 34 supplies the drawn-in treated water to the customer via the sensor 37. 【0084】 Sensor 37 detects the flow of water based on a change in capacitance. When sensor 37 detects water, it transmits a detection signal to control device 36. Upon receiving the detection signal from sensor 37, control device 36 determines that water has been detected by sensor 37 and proceeds to step S23. If no detection signal is received from sensor 37, control device 36 determines that water has not been detected by sensor 37 and proceeds to step S21, maintaining the pump 23 stopped. 【0085】 In step S23, the control device 36 drives the pump 23. 【0086】 In step S24, the control device 36 determines whether or not water has been detected by the sensor 37. Specifically, for example, when a customer finishes using water, they remove their hand from the spout. When the hand is removed from the spout, the infrared sensor stops detecting the customer. When the infrared sensor stops detecting the customer, it stops the detection signal. When the detection signal stops, the control device 36 stops the pump 34. 【0087】 Sensor 37 detects that the water supply has been stopped based on a change in capacitance. When sensor 37 detects that the water supply has been stopped, it stops the detection signal. When the detection signal from sensor 37 is stopped, the control device 36 determines that no water is being detected by sensor 37, proceeds to step S21, and stops the pump 23. If a detection signal is being received from sensor 37, the control device 36 determines that water is being detected by sensor 37, proceeds to step S23, and maintains the operation of the pump 23. 【0088】 As a result, while water is being supplied to consumers, raw water is supplied from the raw water storage tank 21 to the membrane treatment module 10. Furthermore, by controlling pumps 23 and 34 so that the flow rate of raw water sent out by pump 23 and the flow rate of treated water sent out by pump 34 are approximately the same, the amount of raw water sent out from the raw water storage tank 21 is equal to the amount of water supplied to consumers, and the amount of treated water stored in pump 34 is maintained. Therefore, an appropriate amount of treated water is always stored in the treated water storage tank 31. 【0089】 Furthermore, even when water purification is carried out according to water usage, chlorine is not added each time. This is because adding chlorine to the treated water storage tank 31 each time purification is performed would gradually increase the amount of chlorine in the circulation system, making it easier for chlorine to corrode pipes and equipment, and for chlorine by-products to be generated. 【0090】 <Basic Computer Hardware Configuration> Figure 8 is a block diagram showing the basic hardware configuration of computer 90. Computer 90 includes at least a processor 91, main memory 92, auxiliary storage 93, and a communication IF99 (interface). These are electrically connected to each other by a bus. 【0091】 The processor 91 is hardware for executing the instruction set written in the program. The processor 91 consists of an arithmetic unit, registers, peripheral circuits, etc. 【0092】 Main memory 92 is used to temporarily store programs and data processed by programs, etc. For example, it is a volatile memory such as DRAM (Dynamic Random Access Memory). 【0093】 Auxiliary storage device 93 is a storage device for storing data and programs. Examples include flash memory, HDD (Hard Disc Drive), magneto-optical disk, CD-ROM, DVD-ROM, semiconductor memory, etc. 【0094】 A communication IF99 is an interface for inputting and outputting signals for communication with other computers via a network using wired or wireless communication standards. A network consists of various mobile communication systems, such as the Internet, LANs, and wireless base stations. For example, a network includes 3G, 4G, and 5G mobile communication systems, LTE (Long Term Evolution), and wireless networks that can connect to the Internet via designated access points (e.g., Wi-Fi®). When connecting wirelessly, communication protocols include, for example, Z-Wave®, ZigBee®, and Bluetooth®. When connecting via a wired connection, the network also includes connections made directly via USB (Universal Serial Bus) cables, etc. 【0095】 Furthermore, by distributing all or part of each hardware configuration across multiple computers 90 and connecting them to each other via a network, a computer 90 can be virtually realized. Thus, the concept of computer 90 includes not only a computer 90 housed in a single enclosure or case, but also a virtualized computer system. 【0096】 <Basic Functional Configuration of Computer 90> The functional configuration of the computer realized by the basic hardware configuration of computer 90 shown in Figure 8 will be explained. The computer comprises at least one functional unit: a control unit, a memory unit, and a communication unit. 【0097】 Furthermore, the functional units of computer 90 can also be realized by distributing all or part of each functional unit across multiple computers 90 interconnected via a network. The concept of computer 90 includes not only a single computer 90 but also a virtualized computer system. 【0098】 The control unit is realized when the processor 91 reads various programs stored in the auxiliary storage device 93, loads them into the main memory device 92, and executes processing according to those programs. The control unit can realize various functional units that perform information processing depending on the type of program. In this way, the computer is realized as an information processing device that performs information processing. 【0099】 The memory unit is implemented by a main memory 92 and an auxiliary memory 93. The memory unit stores data, various programs, and various databases. The processor 91 can also reserve memory areas corresponding to the memory unit in the main memory 92 or the auxiliary memory 93 according to the program. The control unit can also cause the processor 91 to perform operations such as adding, updating, and deleting data stored in the memory unit according to the various programs. 【0100】 A database, specifically a relational database, is used to manage and link data sets called tables, which are structurally defined by rows and columns. In a database, tables are called tables, the columns of a table are called columns, and the rows of a table are called records. In a relational database, relationships can be established and linked between tables. Typically, each table has a key column to uniquely identify records, but setting a key on a column is not mandatory. The control unit can instruct the processor 91 to add, delete, or update records in specific tables stored in the memory unit according to various programs. 【0101】 The communication unit is implemented by the communication IF99. The communication unit implements the function of communicating with other computers 90 via the network. The communication unit can receive information transmitted from other computers 90 and input it to the control unit. The control unit can cause the processor 91 to perform information processing on the received information according to various programs. The communication unit can also transmit information output from the control unit to other computers 90. 【0102】 While several embodiments of this disclosure have been described above, these embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications are permitted without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. 【0103】 <Note> The details described in each of the above embodiments are noted below. 【0104】 (Note 1) A water treatment system comprising a raw water storage tank for storing raw water, a first water supply means for supplying the raw water stored in the raw water storage tank, a reverse osmosis membrane for separating the supplied raw water into permeate and concentrated water, an activated carbon filter for filtering the permeate, and a treated water storage tank for storing the water that has passed through the activated carbon filter after adding chlorine. (Note 2) The water treatment system as described in Appendix 1, further comprising a second water supply means for supplying water stored in a treated water storage tank to a raw water storage tank if the chlorine concentration of the water stored in the treated water storage tank does not reach a predetermined concentration. (Note 3) The water stored in the treated water storage tank is used for washing, cooking, bathing, showering, or drinking in the water treatment system described in (Appendix 1). (Note 4) The water treatment system described in (Appendix 1) uses concentrated water for flushing toilets, watering plants, landscaping, or emergency water. (Note 5) The water treatment system described in (Appendix 2) uses the water that cannot be stored in the raw water storage tank, of which excess water sent from the treated water storage tank to the raw water storage tank, for outdoor use. (Note 6) The reverse osmosis membrane is a water treatment system described in (Appendix 1) that allows separated permeate to pass through a number of times corresponding to the intended use of the water. (Note 7) A method for supplying raw water stored in a raw water storage tank by a first water supply means, separating the supplied raw water into permeate and concentrated water using a reverse osmosis membrane, filtering the permeate with an activated carbon filter, adding chlorine to the water that has passed through the activated carbon filter, and storing the treated water in a treated water storage tank. (Note 8) The method according to Appendix 7, wherein if the chlorine concentration of the water stored in the treated water storage tank does not reach a predetermined concentration, the second water supply means is controlled to send the water stored in the treated water storage tank to the raw water storage tank. [Explanation of symbols] 【0105】 1... System 100…Buildings 10…Membrane processing module 11… Conductivity sensor 12…Pressure sensor 13…First filter 15...Sensor group 16...Permeable membrane 17…Sensor group 18…Activated carbon filter 19…valve 110... Drainage reservoir 21… Raw water storage tank 22... Ozone generator 23... Pump 24... Pump 31...Treated water storage tank 33…Chlorine supply unit 34... Pump 35...UV sterilization section 36...Control device 37…Sensor

Claims

[Claim 1] A raw water storage tank for storing raw water, A water supply means for supplying raw water stored in the raw water storage tank, A reverse osmosis membrane separates the supplied raw water into permeate and concentrated water. An activated carbon filter for filtering the permeate water, A treated water storage tank that stores water that has passed through the activated carbon filter and to which chlorine is added, A chlorine meter for measuring the chlorine concentration of the water stored in the treated water storage tank, When the chlorine concentration meets predetermined conditions, means for stopping all operations and A water treatment system equipped with the following features. [Claim 2] A first group of sensors that senses the permeate separated by the reverse osmosis membrane, When all of the above operations are stopped, means for storing data sensed by the first group of sensors when the chlorine concentration meets predetermined conditions, A water treatment system according to claim 1, comprising: [Claim 3] A second group of sensors that senses the raw water supplied to the reverse osmosis membrane, When all of the above operations are stopped, means for storing data sensed by the second group of sensors when the chlorine concentration meets predetermined conditions, The water treatment system according to claim 2, comprising: [Claim 4] Raw water stored in a raw water storage tank is transported by a water supply means. The raw water that has been supplied is separated into permeate and concentrated water by a reverse osmosis membrane. The permeate is filtered through an activated carbon filter. Chlorine is added to the water that has passed through the activated carbon filter and stored in a treated water storage tank. The chlorine concentration of the water stored in the treated water storage tank is measured using a chlorine meter. A method for stopping all operations when the chlorine concentration meets predetermined conditions.

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