Reverse osmosis membrane water purifier

Abstract

Provided is a reverse osmosis membrane water purifier capable of maintaining heavy metal removal performance over a long period while exhibiting sufficient heavy metal removal performance.　A reverse osmosis membrane water purifier (100) comprises: a reverse osmosis membrane module (10) that performs a process for allowing introduced water to permeate through a reverse osmosis membrane (10A), the reverse osmosis membrane module (10) separating the water into permeated water that has permeated through the reverse osmosis membrane (10A) and non-permeated water that has not permeated through the reverse osmosis membrane (10A), and discharging the permeated water and the non-permeated water; a permeated water passage part (30) that forms a flow channel through which the permeated water is discharged from the reverse osmosis membrane module (10); and a removal part (60) that is provided to the permeated water passage part (30) and removes heavy metals contained in the permeated water. The permeated water passage part (30) has: a first flow path (31); a second flow path (32) that is parallel to the first flow path (31), the removal part (60) being disposed in the second flow path (32); and a switching part (33) that freely switches to either passage state from among a state in which water can be passed through the first flow path (31) and a state in which water can be passed through the second flow path (32).

Description

reverse osmosis water purifier

[0001] The present disclosure relates to a reverse osmosis membrane water purifier.

[0002] Patent Document 1 discloses a conventional water purifier. This water purifier includes a membrane element having a filter membrane and a heavy metal removal unit. This water purifier produces purified water with reduced dissolved solids in the water, such as water-soluble salts such as calcium and magnesium, and heavy metals such as lead, by sequentially passing water through the membrane element and the heavy metal removal unit.

[0003] In the water purifier of Patent Document 1, a reverse osmosis membrane, a nanofilter, or the like is used as the filter membrane. Of these filter membranes, a reverse osmosis membrane is considered to have excellent performance in removing dissolved solids including heavy metals. Therefore, a water purifier equipped with a heavy metal adsorption unit in addition to a reverse osmosis membrane module can be said to have extremely excellent heavy metal removal performance.

[0004] Chinese Utility Model No. 207243582

[0005] However, reverse osmosis membranes may experience a phenomenon known as creeping. Creeping is a phenomenon in which dissolved solids seep into the permeate when water remains trapped in a reverse osmosis membrane module, such as during shutdown. When this creeping phenomenon occurs, the water discharged at the beginning of purified water production (hereinafter also referred to as "initial water") may have a higher total dissolved solids concentration (TDS concentration) due to the seeped dissolved solids than normal permeate. In other words, in a water purifier using a reverse osmosis membrane, the initial water may contain more dissolved solids than normal permeate.

[0006] In the case of Patent Document 1, the heavy metal removal unit is provided, so that even if heavy metals leak into the permeate side, they can be removed. However, because the heavy metal removal unit is configured to pass the entire amount of permeate discharged from the membrane element, there is a concern that the heavy metal removal performance will deteriorate early.

[0007] An object of the present disclosure is to provide a reverse osmosis membrane water purifier that can exhibit sufficient heavy metal removal performance while maintaining that heavy metal removal performance over a long period of time.

[0008] The reverse osmosis membrane water purifier according to the present disclosure comprises a reverse osmosis membrane module that processes introduced water by passing it through a reverse osmosis membrane and separates it into permeate that has passed through the reverse osmosis membrane and non-permeate that has not passed through the reverse osmosis membrane and discharges the separated water; a permeate flow section that forms a flow path for discharging the permeate from the reverse osmosis membrane module; and a removal section that is provided in the permeate flow section and removes heavy metals contained in the permeate, wherein the permeate flow section has a first flow path, a second flow path that is parallel to the first flow path and in which the removal section is disposed, and a switching section that can freely switch between a water flow state allowing water to pass through the first flow path and a state allowing water to pass through the second flow path.

[0009] 1 is a diagram schematically illustrating a reverse osmosis membrane water purifier according to Embodiment 1. FIG. 2 is a diagram schematically illustrating a reverse osmosis membrane water purifier according to Embodiment 2.

[0010] Embodiments 1 and 2 embodying a reverse osmosis membrane water purifier according to the present disclosure will be described with reference to the drawings. The reverse osmosis membrane water purifier according to each of the following embodiments uses tap water as raw water and produces purified water from this raw water. The purified water is obtained by passing the raw water through a reverse osmosis membrane (reverse osmosis membrane treatment). The TDS concentration of tap water is approximately 25 ppm to 700 ppm. In each of the following embodiments, purified water with a TDS concentration of approximately 20 ppm is produced from this raw water. In addition to tap water, examples of raw water include well water and rainwater.

[0011] <Embodiment 1> As shown in Figure 1, a reverse osmosis membrane water purifier 100 according to Embodiment 1 includes a reverse osmosis membrane module 10, an inlet water flow section 20, a permeate water flow section 30, a non-permeate water flow section 50, a removal section 60, and a control section 70. The reverse osmosis membrane module 10 has a reverse osmosis membrane 10A. The reverse osmosis membrane module 10 filters raw water using a so-called crossflow system. The reverse osmosis membrane module 10 performs reverse osmosis membrane treatment on the introduced water. Each reverse osmosis membrane module 10 separates the water into permeate, which is water that has passed through the reverse osmosis membrane 10A during the reverse osmosis membrane treatment, and non-permeate, which is water that has not passed through.

[0012] As shown in Fig. 1, the reverse osmosis membrane module 10 has an inlet 11, a first outlet 12, and a second outlet 13. Water is introduced into the reverse osmosis membrane module 10 through the inlet 11. The reverse osmosis membrane module 10 discharges permeated water through the first outlet 12 and non-permeated water through the second outlet 13. The permeated water discharged through the first outlet 12 has a reduced TDS concentration compared to the water introduced through the inlet 11. The non-permeated water discharged through the second outlet 13 has a higher TDS concentration than the water introduced through the inlet 11.

[0013] The inlet water passage 20 forms a flow path through which water introduced into the reverse osmosis membrane module 10 flows. The upstream side of the inlet water passage 20 is connected to a water supply source (not shown), and raw water is supplied from this water supply source. The downstream end of the inlet water passage 20 is connected to the inlet 11 of the reverse osmosis membrane module 10. The inlet water passage 20 is provided with, in order from the upstream side of the flow path, a prefilter 20A and a pump 20B. The pump 20B applies a pressure equivalent to reverse osmosis pressure to the water introduced into the reverse osmosis membrane module 10. The pump 20B is driven and controlled by the control unit 70. The prefilter 20A is composed of a filter material such as activated carbon. The prefilter 20A removes turbid components such as particulate matter and free residual chlorine from the raw water before reverse osmosis membrane processing. This allows the reverse osmosis membrane water purifier 100 to prevent clogging and deterioration of the reverse osmosis membrane 10A.

[0014] The permeate flow section 30 forms a flow path through which permeate, which is part of the water discharged from the reverse osmosis membrane module 10, flows. As shown in FIG. 1 , the upstream end of the permeate flow section 30 is connected to the first outlet 12 of the reverse osmosis membrane module 10. The downstream end of the permeate flow section 30 is connected to a water faucet (not shown). The permeate flow section 30 has a first flow path 31, a second flow path 32, and a switching section 33. The first flow path 31 and the second flow path 32 are formed in parallel between the branch point 30A and the junction point 30B. The switching section 33 freely switches between a state allowing water to flow through the first flow path 31 and a state allowing water to flow through the second flow path 32. In this embodiment, the switching of the flow paths by the switching section 33 is controlled by the control unit 70.

[0015] The first flow path 31 is provided with, from upstream to downstream, a first selector valve 33A and a post-filter 30C. The first selector valve 33A, together with a second selector valve 33B (described later), constitute the selector unit 33. The first selector valve 33A opens and closes the first flow path 31 under the control of the controller 70. Like the pre-filter 20A, the post-filter 30C is configured with a filter material such as activated carbon. The post-filter 30C can remove volatile organic compounds (VOCs) and odors from the permeated water. This allows the reverse osmosis membrane water purifier 100 to improve the taste of the permeated water. In this embodiment, the permeated water that passes through the post-filter 30C passes through a junction 30B and is discharged as purified water from a faucet (not shown) downstream of the permeated water flow unit 30.

[0016] The second flow path 32 is provided with, in order from upstream to downstream, a second switching valve 33B, a removal unit 60, and a check valve 32A. The second switching valve 33B, together with the first switching valve 33A provided in the first flow path 31, constitutes the switching unit 33. The second switching valve 33B opens and closes the second flow path 32 by being driven and controlled by the control unit 70. The removal unit 60 removes heavy metals contained in the permeated water. In this embodiment, the removal unit 60 is a filter configured with an adsorbent capable of adsorbing heavy metals such as lead. In addition, the removal unit 60 is configured with a filter material made of activated carbon or the like, similar to the post filter 30C. This allows the removal unit 60 to remove not only heavy metals such as lead, but also VOCs, odors, and other components from the permeated water.

[0017] 1 , the switching unit 33 includes a first switching valve 33A provided in the first flow path 31 and a second switching valve 33B provided in the second flow path 32. The first switching valve 33A and the second switching valve 33B are electrically operated valves driven by actuators such as solenoids and motors. The first switching valve 33A and the second switching valve 33B are controlled by the control unit 70. The first switching valve 33A and the second switching valve 33B are controlled so that when one of them closes the flow path, the other opens the flow path.

[0018] In this embodiment, the permeate water flow section 30 is provided with a pressure sensor (not shown). The pressure sensor detects changes in pressure in the permeate water flow section 30. The pressure in the permeate water flow section 30 changes depending on the opening and closing of a water faucet provided downstream. The pressure sensor detects changes in pressure due to the opening and closing of the faucet and transmits the detection results to the control section 70. The detection results of the pressure sensor are received by the control section 70 as signals indicating the start and end of purified water production.

[0019] The non-permeate water flow section 50 forms a flow path through which non-permeate water discharged from the reverse osmosis membrane module 10 flows. As shown in FIG. 1 , the upstream end of the non-permeate water flow section 50 is connected to the second outlet 13 of the reverse osmosis membrane module 10. The downstream end of the non-permeate water flow section 50 is open. The non-permeate water that has flowed through the non-permeate water flow section 50 is discharged as wastewater from the downstream end of the non-permeate water flow section 50. An on-off valve 51 is provided in the non-permeate water flow section 50. In this embodiment, the on-off valve 51 is a solenoid valve having an orifice (not shown). The on-off valve 51 is opened only during flushing of the reverse osmosis membrane module 10 after purified water production is completed. During purified water production, the on-off valve 51 closes the flow path formed by the non-permeate water flow section 50, allowing non-permeate water to flow downstream only through the orifice. As a result, the reverse osmosis membrane water purifier 100 throttles the flow rate of non-permeated water flowing through the non-permeated water flow section 50 during purified water production, and the pressure of the pump 20B acts effectively on the reverse osmosis membrane 10A as reverse osmosis pressure.

[0020] The control unit 70 controls each part of the reverse osmosis membrane water purifier 100. The control unit 70 is mainly composed of, for example, a microcontroller and includes an arithmetic unit such as a CPU (Central Processing Unit), and storage means such as RAM and ROM. The control unit 70 is connected to the pump 20B, the first switching valve 33A, the second switching valve 33B, the on-off valve 51, etc. The control unit 70 controls each part in accordance with a program for setting the reverse osmosis membrane water purifier 100 that is stored in advance in storage means (not shown).

[0021] The control unit 70 controls the switching unit 33 to switch between the first flow path 31 and the second flow path 32. The control unit 70 controls the switching unit 33 to switch the water flow state so that water is passed through the removal unit 60 for a predetermined time from the start of purified water production, specifically, while water with a relatively high TDS concentration is being discharged from the reverse osmosis membrane module 10 at the beginning of production. This predetermined time from the start of purified water production can be arbitrarily set as the time from the start of purified water production until the TDS concentration settles to a desired TDS concentration. After the initial water is no longer discharged from the reverse osmosis membrane module 10, the control unit 70 controls the switching unit 33 to switch the water flow state so that the subsequent permeated water is discharged without passing through the removal unit 60. As described above, the initial water may contain a larger amount of dissolved solids, including heavy metals, than normal. The control unit 70 controls the drive of the switching unit 33 so that water is allowed to pass through the second flow path 32 at the beginning of purified water production and so that water is allowed to pass through the first flow path 31 at other times.

[0022] In detail, when purified water production starts, the control unit 70 opens the second switching valve 33B and closes the first switching valve 33A in the switching unit 33. This switches the permeate water flow unit 30 from a state where water can flow through the first flow path 31 to a state where water can flow through the second flow path 32. Furthermore, after a predetermined time has elapsed since the start of purified water production, the control unit 70 executes control to open the first switching valve 33A and close the second switching valve 33B in the switching unit 33. This switches the permeate water flow unit 30 from a state where water can flow through the second flow path 32 to a state where water can flow through the first flow path 31.

[0023] In this embodiment, the control unit 70 activates a timer (not shown) when purified water production starts. While the timer continues counting down, the control unit 70 executes control to allow water to pass through the second flow path 32. When the timer countdown ends, the control unit 70 executes control to switch the water flow state to allow water to pass through the first flow path 31. The countdown time of the timer corresponds to the above-mentioned predetermined time. The countdown time can be set, for example, based on a measured time from the start of purified water production until the TDS concentration and heavy metal concentration reach the concentrations measured in permeate from normal reverse osmosis membrane treatment.

[0024] The time from the start of purified water production until the TDS concentration and heavy metal concentration reach the concentration measured in normal permeate water is thought to be related to the time it takes for the accumulated water in the reverse osmosis membrane module, which has become highly concentrated due to creeping, to be discharged. For example, in the configuration of the reverse osmosis membrane water purifier 100 of this embodiment, the TDS concentration settles to the value shown during normal purified water production when approximately 1000 mL to 1500 mL of water is discharged from the start of purified water production. The time required to discharge approximately 1000 mL to 1500 mL of water is approximately 30 to 40 seconds. Therefore, the timer countdown time may be set based on measured values, such as the water flow rate and water flow rate relative to the amount of water accumulated in the reverse osmosis membrane module, for example, the discharge flow rate from the reverse osmosis membrane module, the discharged water volume, the inlet flow rate to the reverse osmosis membrane module, the discharged water volume, the discharged water volume, the discharged water volume from the start of purified water production, and the like. The switching of the water flow state from a state in which water can flow through the second flow path to a state in which water can flow through the first flow path may be performed using indicators such as measurements that directly measure the water flow rate and water flow rate, or actual measurements of values ​​indirectly related to the water flow rate and water flow rate, such as the pump rotation speed and power supply time.

[0025] The operation of the reverse osmosis membrane water purifier 100 having the above-described configuration will be described together with the operation of the reverse osmosis membrane water purifier 100.

[0026] When producing purified water in the reverse osmosis membrane water purifier 100, a user of the reverse osmosis membrane water purifier 100 opens a water faucet (not shown) downstream of the permeate water flow section 30. This causes the reverse osmosis membrane water purifier 100 to begin producing purified water. Specifically, when the faucet is opened, a change in pressure occurs in the flow path of the permeate water flow section 30. The reverse osmosis membrane water purifier 100 detects this pressure change using a pressure sensor (not shown). The pressure sensor transmits a signal (ON signal) to the control unit 70 indicating that a pressure change from closed to open has been detected. Upon receiving the ON signal from the pressure sensor, the control unit 70 starts driving the pump 20B. In addition, upon receiving the ON signal from the pressure sensor, the control unit 70 opens the second switching valve 33B and closes the first switching valve 33A in the switching unit 33. Furthermore, upon receiving the ON signal from the pressure sensor, the control unit 70 starts a countdown using a timer (not shown).

[0027] When the pump 20B starts to operate, raw water is supplied from an upstream water source to the water inlet 20. The raw water flowing through the water inlet 20 passes through the prefilter 20A and flows into the pump 20B, where it is introduced into the reverse osmosis membrane module 10 through the inlet 11 while being pressurized.

[0028] In this way, the water introduced into the reverse osmosis membrane module 10 is separated into permeated water that has permeated the reverse osmosis membrane 10A and non-permeated water that has not permeated the reverse osmosis membrane 10A. The separated permeated water and non-permeated water are discharged to the outside of the reverse osmosis membrane module 10 from the first outlet 12 and the second outlet 13, respectively. The permeated water discharged from the first outlet 12 flows through the permeated water flow section 30 and is discharged from a water faucet (not shown). The non-permeated water discharged from the second outlet 13 flows through the non-permeated water flow section 50 and is discharged from the downstream end as wastewater.

[0029] The permeate discharged from the first outlet 12 flows through the permeate flow section 30. Immediately after the reverse osmosis membrane water purifier 100 starts operating, i.e., at the beginning of purified water production, the permeate flow section 30 is set by the switching section 33 to a state in which water can flow through the second flow path 32. Therefore, the permeate discharged from the first outlet 12 flows into the second flow path 32 from the branch point 30A and flows through the removal section 60. The permeate that passes through the removal section 60 flows downstream through the junction 30B and is discharged from a faucet (not shown). In this way, even if the permeate discharged from the reverse osmosis membrane module 10 has a higher-than-normal heavy metal concentration, the heavy metals are adsorbed by the heavy metal adsorbent by passing through the removal section 60, thereby reducing the heavy metal concentration to an acceptable level. Therefore, even if the permeate has a higher-than-normal heavy metal concentration at the beginning of purified water production, it can be discharged as purified water by passing through the removal section 60.

[0030] The removal section 60 is a filter configured to contain a heavy metal adsorbent and activated carbon similar to that of the post-filter 30C. As a result, the heavy metal concentration of the permeate that flows through the removal section 60 is reduced, and components such as VOCs and odors are also removed. For this reason, in this embodiment, the permeate flow section 30 is configured to allow the permeate to pass through only either the removal section 60 or the post-filter 30C.

[0031] Thereafter, when the countdown by the timer ends, the control unit 70 opens the first switching valve 33A and closes the second switching valve 33B in the switching unit 33. This switches the permeate water flow unit 30 to a state where water can flow through the first flow path 31. Therefore, the permeate water discharged from the first outlet 12 flows into the first flow path 31 from the branch point 30A. The permeate water that has flowed into the first flow path 31 flows through the permeate water flow unit 30, passing through the post filter 30C and the junction point 30B in this order, and is then discharged from a water faucet (not shown).

[0032] As described above, in this embodiment, the countdown time of the timer is set as the time from the start of purified water production until the TDS concentration in the initial water settles to an acceptable value. That is, the permeate discharged from the reverse osmosis membrane module 10 after the countdown ends has a TDS concentration sufficiently reduced to an acceptable value by passing through the reverse osmosis membrane 10A. Therefore, after the countdown ends, the permeate discharged from the reverse osmosis membrane module 10 can be discharged as purified water without passing through the removal unit 60. In this way, the reverse osmosis membrane water purifier 100 prevents unnecessary water flow through the removal unit 60, thereby suppressing a decrease in the heavy metal removal performance of the removal unit 60.

[0033] On the other hand, when purified water is produced, the non-permeated water discharged from the second outlet 13 of the reverse osmosis membrane module 10 flows through the non-permeated water flow section 50 and is discharged as wastewater from the downstream end of the non-permeated water flow section 50. When purified water is produced, the on-off valve 51 is closed in the non-permeated water flow section 50. When purified water is produced, the non-permeated water flows downstream in the non-permeated water flow section 50 only through an orifice (not shown) formed in the on-off valve 51. In this way, the reverse osmosis membrane water purifier 100 limits the flow rate of non-permeated water discharged as wastewater and ensures the reverse osmosis pressure applied to the reverse osmosis membrane 10A.

[0034] When a water tap (not shown) downstream of the permeate water passage section 30 is closed, the reverse osmosis membrane water purifier 100 stops producing purified water. After the production of purified water is completed, the reverse osmosis membrane water purifier 100 starts flushing the reverse osmosis membrane module 10. Specifically, when the water tap is closed and a pressure fluctuation occurs in the permeate water passage section 30, a pressure sensor (not shown) detects this and sends a signal (OFF signal) indicating that a pressure change corresponding to the closure of the tap has been detected to the control unit 70. Upon receiving the OFF signal, the control unit 70 opens the on-off valve 51 in the non-permeate water passage section 50. In this state, the control unit 70 continues to drive the pump 20B for a certain period of time. As a result, the reverse osmosis membrane water purifier 100 replaces water accumulating upstream of the reverse osmosis membrane 10A in the reverse osmosis membrane module 10 with raw water from the water supply source. After a certain time has elapsed since the start of flushing, the control unit 70 stops driving the pump 20B and closes the on-off valve 51, thereby ending the flushing. Note that the certain time is a time that is arbitrarily set as the time for performing the flushing. This time can be set appropriately depending on the flow rate of the water introduced relative to the amount of water that can remain in the reverse osmosis membrane module, similar to the time set for the countdown of the timer described above.

[0035] As described above, the reverse osmosis membrane water purifier 100 according to the first embodiment includes a reverse osmosis membrane module 10, a permeate flow unit 30, and a removal unit 60. The reverse osmosis membrane module 10 processes introduced water by passing it through the reverse osmosis membrane 10A, separating the water into permeate that has passed through the reverse osmosis membrane 10A and non-permeate that has not passed through the reverse osmosis membrane 10A and discharging the separated water. The permeate flow unit 30 forms a flow path for discharging the permeate from the reverse osmosis membrane module 10. The removal unit 60 is provided in the permeate flow unit 30 and removes heavy metals contained in the permeate. The permeate flow unit 30 includes a first flow path 31, a second flow path 32, and a switching unit 33. The first flow path 31 and the second flow path 32 are flow paths formed in parallel with each other. The removal unit 60 is disposed in the second flow path 32. The switching unit 33 freely switches between a state allowing water to pass through the first flow path 31 and a state allowing water to pass through the second flow path 32.

[0036] The reverse osmosis membrane water purifier 100 includes a removal unit 60, which allows permeate water with reduced heavy metal concentrations to be passed through the removal unit 60 and discharged as purified water. The reverse osmosis membrane water purifier 100 processes initial water to remove heavy metals and discharges the purified water, thereby reducing the amount of wastewater compared to when the initial water is discarded. The reverse osmosis membrane water purifier 100 includes a permeate flow unit 30 having a first flow path 31, a second flow path 32, and a switching unit 33. This allows only water with a higher-than-normal heavy metal concentration, such as water discharged from the reverse osmosis membrane module 10 at the beginning of purified water production, to pass through the removal unit 60, while not passing other permeate through the removal unit 60. This allows the reverse osmosis membrane water purifier 100 to avoid unnecessary water flow through the removal unit 60. As a result, the reverse osmosis membrane water purifier 100 can suppress deterioration of the filter material compared to when water is constantly passed through the removal unit. Therefore, the reverse osmosis membrane water purifier 100 can exhibit sufficient heavy metal removal performance and maintain the heavy metal removal performance for a long period of time.

[0037] The reverse osmosis membrane water purifier 100 includes a control unit 70. The control unit 70 controls the switching between the first flow path 31 and the second flow path 32 by the switching unit 33 based on the start and end of a countdown of a timer (not shown). With this configuration, the reverse osmosis membrane water purifier 100 can automatically and appropriately switch the flow path in the permeate water flow unit 30. The reverse osmosis membrane water purifier 100 can easily and reliably switch the flow path compared to, for example, manually operating the switching unit 33 to switch the flow path. As a result, the reverse osmosis membrane water purifier 100 can easily and reliably switch between passing water through the removal unit 60 when necessary and not passing water through the removal unit 60 when not necessary.

[0038] In the reverse osmosis membrane water purifier 100, the removal unit 60 is configured with a heavy metal adsorbent and activated carbon as filtering materials. The reverse osmosis membrane water purifier 100 is equipped with a post filter 30C. The post filter 30C is configured with activated carbon as filtering materials. The post filter 30C is arranged in the first flow path 31, which is parallel to the second flow path 32 in which the removal unit 60 is arranged. This allows the reverse osmosis membrane water purifier 100 to suppress deterioration of the filtering material in the post filter 30C. That is, because the permeated water flowing through the second flow path 32 is not passed through the post filter 30C, deterioration of the filtering material is suppressed compared to when the entire amount of permeated water is passed through. In addition to having reduced heavy metal concentrations, the permeated water that has passed through the removal unit 60 also has reduced VOCs, odors, and the like, similar to when passing through the post filter 30C.

[0039] 2, a reverse osmosis membrane water purifier 200 according to Embodiment 2 includes a reverse osmosis membrane module 10, an inlet water flow section 20, and a non-permeate water flow section 50 similar to those of Embodiment 1. The reverse osmosis membrane water purifier 200 differs from Embodiment 1 in that it includes a permeate water flow section 230 having a different configuration from the permeate water flow section 30 of Embodiment 1, and in that the removal section 260 is configured to include a second reverse osmosis membrane module 210. The same components as those in Embodiment 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

[0040] 2, the permeate flow section 230 is similar to that of the first embodiment in that it forms a first flow path 31 and a second flow path 32 that are parallel to each other between the branch point 30A and the junction 30B, and in that a removal section 260 is disposed in the second flow path 32. The permeate flow section 230 of the second embodiment differs from the permeate flow section 30 of the first embodiment in that a post filter 30C is provided downstream of the junction 30B, and in that it includes a concentration measurement section 280.

[0041] 2, the post filter 30C in this embodiment is disposed in the permeate flow section 230 downstream of the junction 30B. Therefore, in the reverse osmosis membrane water purifier 200, all of the permeate flowing through the permeate flow section 230 passes through the post filter 30C. This enables the reverse osmosis membrane water purifier 200 to remove VOCs, odors, and the like from the permeate flowing through the second flow path 32.

[0042] The concentration measurement unit 280 is located upstream of the removal unit 260 in the permeate flow unit 230 and measures the TDS concentration of the permeate flowing through the permeate flow unit 230. In this embodiment, the concentration measurement unit 280 is located upstream of the second reverse osmosis membrane module 210 in the second flow path 32 and measures the TDS concentration of the permeate introduced into the second reverse osmosis membrane module 210. The measurement results by the concentration measurement unit 280 are transmitted to the control unit 270, which will be described later.

[0043] As described above, the initial water in a typical reverse osmosis membrane water purifier may have a higher TDS concentration than normal permeate due to creeping. If heavy metals such as lead are present, the heavy metal concentration may also be elevated. Therefore, in the reverse osmosis membrane water purifier 200, the permeate flow section 230 monitors the TDS concentration of the permeate and passes the permeate through the removal section 260 until the measured TDS concentration falls below a predetermined value to remove heavy metals. When the measured TDS concentration falls below the predetermined value, the reverse osmosis membrane water purifier 200 determines that the heavy metal concentration is also acceptable, and discharges the permeate as purified water without passing it through the removal section 260. The predetermined TDS concentration can be set appropriately within a range where the heavy metal concentration is acceptable, for example, based on the correlation between the actually measured heavy metal concentration and the TDS concentration.

[0044] For example, in the configuration of a reverse osmosis membrane water purifier according to the present disclosure, the initial TDS concentration of the water peaks at approximately 200 ppm to 300 ppm. In contrast, the TDS concentration of normal purified water is approximately 20 ppm. If heavy metals are contained in the purified water, it is assumed that the heavy metal concentration will be higher than that of normal purified water until the TDS concentration decreases to the TDS concentration of normal purified water. In other words, if the TDS concentration measured at the beginning of purified water generation decreases to the value measured in normal purified water, it is assumed that even if heavy metals are contained, their concentration has also decreased sufficiently. Therefore, from the viewpoint of reliability, it is desirable to set the predetermined value of the TDS concentration to the TDS concentration of normal purified water.

[0045] Similar to the first embodiment, the removal unit 260 is disposed in the second flow path 32 in the permeate flow unit 230. In this embodiment, the removal unit 260 is a second reverse osmosis membrane module 210 having a second reverse osmosis membrane 210A. The second reverse osmosis membrane module 210 performs a process in which the permeate that has been subjected to reverse osmosis membrane treatment in the reverse osmosis membrane module 10 is further passed through the second reverse osmosis membrane 210A for the purpose of removing heavy metals. As described above, among various filter membranes, reverse osmosis membranes are considered to have excellent dissolved solid removal performance. In the second embodiment, these properties of reverse osmosis membranes are utilized to remove heavy metals by reverse osmosis membrane treatment.

[0046] 2 , the second reverse osmosis membrane module 210 has an inlet 211, a first outlet 212, and a second outlet 213. The second reverse osmosis membrane module 210 receives permeated water discharged from the reverse osmosis membrane module 10 through the inlet 211 and further subjects the permeated water to reverse osmosis membrane treatment. The second reverse osmosis membrane module 210 discharges permeated water that has permeated the second reverse osmosis membrane 210A through the first outlet 212, and discharges non-permeated water that has not permeated the second reverse osmosis membrane 210A through the second outlet 213.

[0047] 2, the second outlet 213 is connected to the upstream end of the second non-permeate water flow section 250. The downstream end of the second non-permeate water flow section 250 is connected to the junction 50A in the non-permeate water flow section 50. The second non-permeate water flow section 250 is provided with a second on-off valve 251. Like on-off valve 51, the second on-off valve 251 is a solenoid valve having an orifice (not shown), and is opened only during flushing of the second reverse osmosis membrane module 210 after purified water production has been completed.

[0048] The control unit 270 controls the switching unit 33 to switch between the first flow path 31 and the second flow path 32. Specifically, the control unit 270 controls the switching unit 33 to switch the water flow state so that the permeated water flows through the removal unit 260 at the beginning of operation of the reverse osmosis membrane water purifier 200. In this embodiment, the control unit 270 controls the switching unit 33 to switch between the first flow path 31 and the second flow path 32 based on the measurement result of the concentration measurement unit 280. The control unit 270 sets the second flow path 32 to a state where water can flow when the reverse osmosis membrane water purifier 200 starts operating, and monitors the TDS concentration of the permeated water in this state. When the measurement result of the TDS concentration by the concentration measurement unit 280 is equal to or lower than a predetermined value, the control unit 270 switches the first flow path 31 to a state where water can flow.

[0049] Specifically, when the control unit 270 receives an ON signal from a pressure sensor or the like indicating the start of purified water production, it executes control to open the second selector valve 33B and close the first selector valve 33A. As a result, the permeate flow unit 230 allows water to pass through the second flow path 32, and permeate discharged from the reverse osmosis membrane module 10 is passed through the removal unit 260. When the TDS concentration measurement result by the concentration measurement unit 280 exceeds a predetermined value, the control unit 270 maintains the second flow path 32 in a passable state. When the TDS concentration measurement result by the concentration measurement unit 280 is confirmed to be equal to or lower than the predetermined value, the control unit 270 executes control to open the first selector valve 33A and close the second selector valve 33B. As a result, the permeate flow unit 230 allows water to pass through the first flow path 31, closes the second flow path 32, and stops passing water to the removal unit 260.

[0050] Note that creeping may also occur in the second reverse osmosis membrane module 210. In this embodiment, to avoid this, the control unit 270 maintains a state in which water can pass through the second flow path 32 for a while even after it is confirmed that the TDS concentration measurement result by the concentration measurement unit 280 is below the predetermined value. This allows the reverse osmosis membrane water purifier 200 to fill the interior of the second reverse osmosis membrane module 210 with water having a TDS concentration below the predetermined value. Once this state is reached, the control unit 270 executes control to switch the second flow path 32 to a state in which water cannot pass through. By executing such control, even if creeping occurs in the second reverse osmosis membrane module 210, an increase in the TDS concentration of the initial water due to creeping is suppressed.

[0051] In the reverse osmosis membrane water purifier according to the present disclosure, when the measurement result of the TDS concentration of the permeate by the concentration measurement unit is confirmed to be equal to or less than a predetermined value, the control unit can control the switching unit to switch from a state in which water can pass through the second flow path to a state in which water can pass through the first flow path after a predetermined time has elapsed. The predetermined value is a value set based on the TDS concentration measured in normal purified water. For example, in the case of the second embodiment, the TDS concentration measured in normal purified water is 20 ppm as described above.

[0052] The predetermined time is set based on, for example, the time from when it is confirmed that the TDS concentration measurement result is equal to or lower than a predetermined value until the second reverse osmosis membrane module is filled with water having a TDS concentration equal to or lower than the predetermined value. In the second embodiment, the predetermined time is set to 40 seconds. Note that the predetermined time may also be set based on the volume, permeate volume, permeate flow rate, etc. of the second reverse osmosis membrane module.

[0053] The reverse osmosis membrane water purifier 200 according to the second embodiment configured as described above can exhibit sufficient heavy metal removal performance and maintain the heavy metal removal performance for a long period of time, as in the first embodiment. In the reverse osmosis membrane water purifier 200, the removal unit 260 includes a second reverse osmosis membrane module 210 having a second reverse osmosis membrane 210A. Therefore, the reverse osmosis membrane water purifier 200 can reduce not only the heavy metal concentration but also the TDS concentration in the initial water overall.

[0054] In the reverse osmosis membrane water purifier 200, the permeate flow unit 230 has a concentration measurement unit 280 that measures the TDS concentration of the permeate flowing through the second flow path 32. The reverse osmosis membrane water purifier 200 is equipped with a control unit 270. The control unit 270 controls the switching unit 33 to switch between the first flow path 31 and the second flow path 32 based on the measurement results of the concentration measurement unit 280. With this configuration, the reverse osmosis membrane water purifier 200 can appropriately switch the flow path in the permeate flow unit 230 based on the actually measured TDS concentration of the permeate. By including the concentration measurement unit 280, the reverse osmosis membrane water purifier 200 can determine whether the TDS concentration of the permeate is appropriate.

[0055] The present disclosure is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments, for example, are also included within the technical scope of the present disclosure.

[0056] The configuration of the removal unit according to the present disclosure is not limited to the configurations of the above-described embodiments, and the removal unit may have any configuration as long as it is provided in the permeate flow unit and removes heavy metals contained in the permeate.

[0057] The configuration of the switching unit according to the present disclosure is not limited to that of the above-described embodiments. The switching unit may be configured to include, for example, a three-way valve as a switching valve. The three-way valve may be disposed at the branch point between the first flow path and the second flow path. In this case, the number of valves can be reduced compared to the above-described embodiments, resulting in a reverse osmosis membrane water purifier with a simpler configuration.

[0058] When the reverse osmosis membrane water purifier according to the present disclosure includes a concentration measurement unit, its location is not limited to that of the above-described embodiment 2. The concentration measurement unit may be located upstream of the removal unit in the permeate flow unit.

[0059] The reverse osmosis membrane water purifier according to the present disclosure does not necessarily need to include a control unit. In the reverse osmosis membrane water purifier, the switching of the flow path by the switching unit may be performed manually.

[0060] In the reverse osmosis membrane water purifier according to the present disclosure, the signal indicating the start and end of water discharge is not limited to the detection signal from the pressure switch exemplified in each of the above embodiments. The signal indicating the start and end of water discharge may be, for example, a signal from a detection sensor in an automatic water faucet, a signal transmitted from a manual water discharge stop switch, etc.

[0061] In the reverse osmosis membrane water purifier according to the present disclosure, the pre-filter, post-filter, etc. are not essential components. When a pre-filter and a post-filter are provided, their configurations are not limited to those exemplified in the above embodiment.

[0062] In the first embodiment, the water flow state was switched from a state in which water was allowed to flow through the second flow path to a state in which water was allowed to flow through the first flow path based on the end of the countdown of the timer, i.e., based on time, and in the second embodiment, the water flow state was switched based on the measurement result of the concentration measurement unit that measures the TDS concentration, i.e., based on the TDS concentration. Without being limited to these, the switching of the water flow state in the reverse osmosis membrane water purifier according to the present disclosure may be based on, for example, the discharge flow rate of purified water from the start of purified water production, the discharge flow rate of permeated water from the reverse osmosis membrane module, the introduction flow rate of raw water into the reverse osmosis membrane module, etc.

[0063] As described above, the time from the start of purified water generation until the TDS concentration and heavy metal concentration stabilize to the concentration measured during normal water discharge is thought to be related to the time until the stagnant water in the reverse osmosis membrane module, which has become highly concentrated due to creeping, is discharged. Therefore, the water flow state may be switched based on, for example, the measurement results of the measurement unit that measures the above-mentioned various flow rates, pump rotation speed, power supply time, etc. The time from the start of purified water generation until the water flow state is switched may be preset based on the measurement results of the flow rate, etc., and the time may be switched based on the completion of a countdown of a timer that measures this time.

[0064] 10, 210: reverse osmosis membrane module, 10A, 210A: reverse osmosis membrane, 30, 230: permeate water flow section, 31: first flow path, 32: second flow path, 33: switching section, 60, 260: removal section, 70, 270: control section, 100, 200: reverse osmosis membrane water purifier, 280: concentration measurement section

Claims

1. A reverse osmosis membrane water purifier comprising: a reverse osmosis membrane module which processes introduced water by passing it through a reverse osmosis membrane and separates it into permeated water that has passed through the reverse osmosis membrane and non-permeated water that does not pass through the reverse osmosis membrane and discharges them; a permeated water flow section which forms a flow path for discharging the permeated water from the reverse osmosis membrane module; and a removal section which is provided in the permeated water flow section and removes heavy metals contained in the permeated water, wherein the permeated water flow section has a first flow path, a second flow path which is parallel to the first flow path and in which the removal section is disposed, and a switching section which can freely switch the water flow state between a state where water can pass through the first flow path and a state where water can pass through the second flow path.

2. The reverse osmosis membrane water purifier according to claim 1, wherein the removal section has a second reverse osmosis membrane module having a second reverse osmosis membrane.

3. A reverse osmosis membrane water purifier as described in any one of claims 1 and 2, wherein the permeate flow section has a concentration measuring section which measures the TDS concentration of the permeate flowing through the second flow path, and a control section which controls the switching section to switch between the first flow path and the second flow path based on the measurement results of the concentration measuring section.

4. The reverse osmosis membrane water purifier of claim 3, wherein when it is confirmed that the measurement result of the TDS concentration of the permeated water by the concentration measuring unit is equal to or lower than a predetermined value, the control unit controls the switching unit to switch from a state in which water can pass through the second flow path to a state in which water can pass through the first flow path after a predetermined period of time has elapsed.

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