Water treatment equipment

Abstract

To provide a water treatment apparatus capable of improving a system recovery rate of the whole water treatment apparatus by keeping a recovery rate in a recovery RO module at a substantially constant value.SOLUTION: A water treatment apparatus includes: a recovery RO module separating RO drain water into return water and non-recovery drain water by using a reverse osmotic membrane to the RO drain water; a recovery RO pump; a RO drain channel guiding the RO drain water to the recovery RO pump; a pressure sensor detecting the pressure of the RO drain water; a return water amount sensor detecting a generation amount of return water; a first drain regulation valve disposed in the middle of the RO drain channel; a non-recovery drain channel guiding the non-recovery drain water to an exhaust port; and a second drain regulation valve disposed in the middle of the non-recovery drain channel. The recovery RO pump is controlled based on the detection result of the return water amount sensor, the first drain regulation valve is controlled based on the detection result of the pressure sensor, and the second drain regulation valve is controlled based on a previously set target recovery rate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a water treatment apparatus for producing artificial dialysis water used in dialysis treatment. [Background technology]

[0002] A conventional dialysis water production system will be explained using Figure 3. As shown in Figure 3, hemodialysis water is typically produced from raw water, such as tap water or well water.

[0003] The raw water is first stored in the raw water tank 51. Inside the raw water tank 51, a heating heater 51h is installed to heat the raw water to 25°C. If the temperature of the raw water remains below 25°C, silica components and other substances in the raw water may precipitate in subsequent equipment, potentially causing malfunctions.

[0004] The raw water, heated to 25°C, is then sent to the pretreatment unit 53 by the raw water pump 52. The pretreatment unit 53 has a pre-filter 53a, a water softener 53b, and a carbon filter 53c in that order. The pre-filter 53a mainly filters out impurities (debris) from the raw water, and the water softener 53b mainly filters out calcium ions (Ca) from the raw water. 2+ ) and magnesium ions (Mg 2+ The carbon filter 53c removes residual chlorine (total chlorine: free chlorine + combined chlorine) from the raw water.

[0005] After pretreatment in the pretreatment unit 53, the raw water is sent to the RO unit 54 (reverse osmosis membrane treatment device). The RO unit 54 uses the RO pump 54p to supply the pretreated raw water into the RO module 54m. The RO module 54m removes all inorganic ions contained in the raw water. The RO water (approximately 50-70% of the raw water) that has been treated in the RO module 54m is sent to the RO water supply unit 55. Of the RO wastewater generated by the treatment in the RO module 54m, a portion (also called "recirculating water") is reintroduced into the RO module 54m via the RO pump 54p, and another portion (approximately 30-50% of the raw water, also called "concentrated water") is treated as wastewater.

[0006] The RO water supply unit 55 has an RO water tank 55t in which RO water is stored. A UV irradiation device 55u is installed inside the RO water tank 55t, allowing the RO water to be treated with UV irradiation. In addition, an air filter 55f is installed inside the RO water tank 55t to remove airborne bacteria and debris from the outside air that flows in depending on the change in the water level of the RO water inside the RO water tank 55t.

[0007] RO water stored in the RO water tank 55t is sent to the UF57 (ultrafilter, also called the "limit filtration membrane") via the water pump 56. The UF57 removes biological impurities from the RO water. The RO water, from which biological impurities have been removed by the UF57, is sent to various medical devices for dialysis treatment as dialysis water. Typically, in these medical devices, the dialysis water is heated to around 36°C and used for various dialysis treatments. After circulating through the medical devices, the dialysis water returns to the UF58 (ultrafilter, also called the "limit filtration membrane") and is then returned to the RO water tank 55t.

[0008] The dialysis water production apparatus described above, as shown in Figure 3, is already in practical use and is stably producing artificial dialysis water for dialysis treatment.

[0009] Furthermore, in Patent Document 1, the applicant has proposed a water treatment apparatus comprising: a silica concentration sensor for measuring the silica concentration of raw water; a pretreatment unit for pretreatment of the raw water; an RO module for separating the raw water pretreated by the pretreatment unit into RO water and RO wastewater using a reverse osmosis membrane; a pH sensor for measuring the pH of the RO wastewater; and a control unit that controls the recovery rate of the RO module based on the silica concentration measured by the silica concentration sensor and the pH measured by the pH sensor.

[0010] According to this water treatment system, the control unit controls the recovery rate of the RO module based on the silica concentration of the raw water and the pH of the RO wastewater, thereby enabling the adoption of a more optimal recovery rate, reducing the amount of RO wastewater discharged, and ultimately lowering the cost related to raw water.

[0011] Furthermore, the applicant is a manufacturer of the dialysis water production device shown in Figure 3. The applicant has found that by providing a separate recovery RO module from the RO module 54m, and treating the RO wastewater from the RO module 54m using the recovery RO module and reusing a portion of it as return water, the recovery rate of the water treatment device can be improved.

[0012] Specifically, as shown in Figure 4, the system includes a recovery RO module 61 that separates RO wastewater into return water and non-recoverable wastewater using a reverse osmosis membrane, a recovery RO pump 62 that supplies RO wastewater to the recovery RO module 61, an RO drainage channel 63 extending from the RO module 54m to guide RO wastewater to the recovery RO pump 62, a first drainage adjustment valve 64 located in the middle of the RO drainage channel 63, and a non-recoverable drainage channel 65 extending from the recovery RO module 61 to guide the non-recoverable wastewater to a drain outlet 66. The RO wastewater from the RO module 54m is processed using the recovery RO module 61, and a portion is reused as return water. A water treatment device like the one shown in Figure 4 is already available on the market from the applicant (model name: MIE series). [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] Japanese Patent Publication No. 2017-221311 [Overview of the project] [Problems that the invention aims to solve]

[0014] In the water treatment apparatus shown in Figure 4 (specifically, for example, MIE752 by the present applicant), the amount of return water generated in the recovery RO module 61 is detected by a return water volume sensor 68, and the recovery RO pump 62 is controlled based on the detection result of the return water volume sensor 68 (inverter control).

[0015] Specifically, for example, when the detection result by the return water volume sensor 68 is greater than the value corresponding to the target system recovery rate, the inverter value of the recovery RO pump 62 is reduced. Conversely, when the detection result by the return water volume sensor 68 is smaller than the value corresponding to the target system recovery rate, the inverter value of the recovery RO pump 62 is increased.

[0016] Furthermore, in the water treatment apparatus shown in Figure 4, in order to ensure stable operation of the recovery RO pump 62, the pressure of the RO wastewater supplied to the recovery RO pump 62 must be above a predetermined pressure (for example, 0.1 MPa or higher).

[0017] Here, the operating state of the RO module 54m fluctuates depending on the desired amount of RO water produced (which may be set according to the water level of the recovered RO water tank 55t described later, or as desired), and the amount of RO wastewater guided by the RO drainage channel 63 also fluctuates accordingly.

[0018] To ensure that the pressure of the RO wastewater sent to the recovery RO pump 62 (monitored by the pressure sensor 67) is always above a predetermined pressure, in response to such fluctuations in the amount of RO wastewater, the operator performs a pre-adjustment run of the water treatment device and manually adjusts and determines the opening degree of the first wastewater adjustment valve 64 (once adjusted, the opening degree of the first wastewater adjustment valve 64 remains fixed).

[0019] As shown in the table in Figure 2 as a comparative example, according to the water treatment apparatus shown in Figure 4 (specifically, the model name by the applicant: MIE752), the opening degree of the first drain adjustment valve 64 is manually adjusted and determined based on a pre-adjustment operation, so that the RO drain pressure (monitored by the pressure sensor 67) is guaranteed to be a predetermined pressure (e.g., 0.1 MPa or higher).

[0020] Furthermore, the recovery RO pump 62 is inverter-controlled based on the detection results of the return water volume sensor 68, so that the recovery rate (wastewater recovery membrane recovery rate) in the recovery RO module 61 is kept within the range of 63.6 to 67.3%.

[0021] At this time, the detection result of the return water volume sensor 68 was within the range of 6.7 to 10.5 L / min, and the wastewater flow rate (wastewater recovery RO wastewater flow rate) flowing from the non-recovery wastewater channel 65 to the drain outlet 66 was within the range of 4.0 to 5.2 L / min. Also at this time, the flow rate of RO water generated by the RO module 54m (RO treated water flow rate) was 21.0 to 34.8 L / min, the recovery rate in the RO module 54m (RO membrane recovery rate) was 66.0 to 69.9%, and the overall system recovery rate of the water treatment device was 83.5 to 87.7%.

[0022] Here, in addition to ensuring that the pressure of the RO drain water fed into the recovery RO pump 62 is not less than a predetermined pressure, the present inventor automatically controls the opening degree of the first drain adjustment valve 64 so as to greatly suppress the amount of fluctuation of the pressure, and a second drain adjustment valve is provided in the middle of the non-recovery drain passage 65 and the second drain adjustment valve is automatically controlled based on a preset target recovery rate, whereby it becomes possible to maintain the recovery rate (drain water recovery membrane recovery rate) in the recovery RO module 61 at a substantially constant value, and as a result, it has been found that the system recovery rate of the entire water treatment apparatus can be improved.

[0023] The present invention has been devised based on the above findings. An object of the present invention is to provide a water treatment apparatus capable of improving the system recovery rate of the entire water treatment apparatus by maintaining the recovery rate in the recovery RO module at a substantially constant value.

[0024] Note that the RO water produced by the present invention is not limited to water for artificial dialysis, and can also be used as water for instrument cleaning, inspection water, handwashing water, dispensing water, and the like.

Means for Solving the Problems

[0025] The present invention relates to a water treatment apparatus comprising: an RO module that separates raw water into RO water and RO wastewater using a reverse osmosis membrane; a recovery RO module that separates the RO wastewater into return water and non-recoverable wastewater using a reverse osmosis membrane; a recovery RO pump that supplies the RO wastewater to the recovery RO module; an RO drainage channel extending from the RO module and guiding the RO wastewater to the recovery RO pump; a pressure sensor that detects the pressure of the RO wastewater supplied to the recovery RO pump; a return water volume sensor that detects the amount of return water produced in the recovery RO module; a first drainage control valve provided in the middle of the RO drainage channel; a non-recoverable drainage channel extending from the recovery RO module and guiding the non-recoverable wastewater to a drain outlet; and a second drainage control valve provided in the middle of the non-recoverable drainage channel, wherein the recovery RO pump is controlled based on the detection result of the return water volume sensor, the first drainage control valve is controlled based on the detection result of the pressure sensor, and the second drainage control valve is controlled based on a preset target recovery rate.

[0026] According to the inventor's findings, by controlling the recovery RO pump based on the detection result of the return water volume sensor, controlling the first drain adjustment valve based on the detection result of the pressure sensor, and controlling the second drain adjustment valve based on a preset target recovery rate, it becomes possible to maintain the recovery rate (wastewater recovery membrane recovery rate) in the recovery RO module at a substantially constant value, thereby improving the overall system recovery rate of the water treatment device.

[0027] The water treatment apparatus according to the present invention further comprises, for example, an RO pump that supplies raw water to the RO module, and an RO water volume sensor that detects the amount of RO water produced in the RO module, wherein the RO pump is controlled based on the detection result of the RO water volume sensor.

[0028] In this embodiment, the amount of RO wastewater led from the RO module through the RO drain channel fluctuates depending on the amount of RO water generated (which may be set according to the water level in the RO water tank, or may be set as desired). However, according to the present invention, it is possible to maintain the recovery rate (wastewater recovery membrane recovery rate) in the recovery RO module at a substantially constant value despite (absorbing) such fluctuations in the amount of RO wastewater.

[0029] Furthermore, in the present invention, it is preferable that a raw water tank for storing the raw water is provided upstream of the RO module, and an RO tank for storing the RO water is provided downstream of the RO module, and that the return water is selectively returned to the raw water tank or to the RO tank. This allows the return water (recovered RO membrane treated water) to be used as dialysis water in emergencies such as when the RO module malfunctions and RO water cannot be produced.

[0030] Furthermore, in the present invention, it is preferable to further provide a raw water drainage channel that extends from the upstream side of the RO module and guides raw water to the RO drainage channel. This allows for the use of the return water (recovered RO membrane treated water) from the recovery RO module as dialysis water in emergencies such as when the RO module malfunctions and RO water cannot be produced. [Effects of the Invention]

[0031] According to the present invention, in addition to the recovery RO pump being controlled based on the detection result of the return water volume sensor, the first drain adjustment valve is controlled based on the detection result of the pressure sensor, and the second drain adjustment valve is controlled based on a preset target recovery rate. This makes it possible to maintain the recovery rate (wastewater recovery membrane recovery rate) in the recovery RO module at a substantially constant value, and consequently improve the overall system recovery rate of the water treatment device. [Brief explanation of the drawing]

[0032] [Figure 1] This is a schematic diagram of a water treatment device according to one embodiment of the present invention. [Figure 2] This table shows various data regarding the examples and comparative examples. [Figure 3] This is a schematic diagram of a conventional dialysis water production system. [Figure 4] This is a schematic diagram of a conventional dialysis water production device developed by the applicant. [Modes for carrying out the invention]

[0033] Embodiments of the present invention will be described below with reference to the drawings.

[0034] (Overall structure) Figure 1 is a schematic diagram illustrating a water treatment apparatus according to one embodiment of the present invention. As shown in Figure 1, the water treatment apparatus 10 of this embodiment comprises a raw water tank 11 in which raw water is stored and a heating heater 11h is provided for heating the raw water, a pretreatment unit 13 for pretreatment of the raw water heated in the raw water tank 11, and an RO module 14m that separates the raw water pretreated by the pretreatment unit 13 into RO water and RO wastewater using a reverse osmosis membrane (RO).

[0035] In this embodiment, tap water is used as the raw water. The raw water, which is tap water, is stored in the raw water tank 11. The heating heater 11h is installed inside the raw water tank 11 and, in this embodiment, heats the raw water to 25°C. If the temperature of the raw water remains below 25°C, silica components and other substances in the raw water may precipitate in subsequent devices, potentially causing malfunctions.

[0036] As shown in Figure 1, raw water heated to 25°C is sent to the pretreatment unit 13 by the raw water pump 12. The pretreatment unit 13 has a prefilter 13a, a water softener 13b, and a carbon filter 13c in that order. The prefilter 13a is mainly for filtering out impurities (debris) in the raw water, and the water softener 13b is mainly for filtering out calcium ions (Ca) in the raw water. 2+ ) and magnesium ions (Mg 2+ The carbon filter 13c is designed to remove chlorine, and is primarily used to remove residual chlorine (total chlorine: free chlorine + combined chlorine) from the raw water.

[0037] The raw water, after pretreatment in the pretreatment unit 13, is sent to the RO unit 14 (reverse osmosis membrane treatment device). The RO unit 14 uses an RO pump 14p to supply the pretreated raw water into the RO module 14m. The RO module 14m removes all inorganic ions contained in the raw water. The RO water, after treatment in the RO module 14m, is sent to the RO water supply unit 15. Of the RO wastewater generated by the treatment in the RO module 14m, a portion (also called "recirculating water") is reintroduced into the RO module 14m via the RO pump 14p, while another portion (approximately 30-50% of the raw water, also called "concentrated water") is treated as wastewater.

[0038] More specifically, in the water treatment apparatus 10 of this embodiment, an RO drainage channel 33 for discharging RO wastewater extends from the RO module 14m, and a circulation channel 23 branches off from the RO drainage channel 33 at a branching section 22 and merges with the upstream side of the RO pump 14p. The circulation channel 23 makes it possible to merge a portion of the RO wastewater as "circulating water" with the raw water that has been pretreated by the pretreatment unit 13. A circulation water volume adjustment valve 24 is provided in the middle of the circulation channel 23, and a first drainage adjustment valve 34 is provided in the middle of the RO drainage channel 33 downstream of the branching section 22.

[0039] The control unit 30 (for example, a control panel) then coordinately controls the RO pump 14p and the first drain adjustment valve 34 based on, for example, the desired amount of RO water to be produced and the desired drainage pressure of the RO module 14m (pressure detected by the pressure sensor 37 described later), which are input by the user (however, the control of the first drain adjustment valve 34 described later takes precedence).

[0040] More specifically, the amount of raw water (excluding the amount of circulating water) introduced into the RO module 14m is Q1(m 3 Let Q2(m³) be the amount of RO water treated by RO module 14m. 3 When given ( / h), the RO wastewater discharge volume (excluding the amount of circulating water) is (Q1-Q2)(m 3 It can be expressed as / h), and the recovery rate (%) can be expressed as Q2 / Q1 × 100.

[0041] The RO water supply unit 15 has an RO water tank 15t in which RO water is stored. A UV irradiation device 15u is installed inside the RO water tank 15t, allowing the RO water to be treated with UV irradiation. In addition, an air filter 15f is installed inside the RO water tank 15t to remove airborne bacteria and debris from the outside air that flows in depending on the change in the water level of the RO water inside the RO water tank 15t.

[0042] RO water stored in the 15t RO water tank is sent to the UF17 (ultrafilter, also called the "limit filtration membrane") via the water pump 16. The UF17 removes biological impurities from the RO water. The RO water, from which biological impurities have been removed by the UF17, is sent as dialysis water to various medical devices (not shown) used for dialysis treatment. Typically, in these medical devices, the dialysis water is heated to 36°C and used for various dialysis treatments. After circulating through the medical devices, the dialysis water returns to the UF18 (ultrafilter, also called the "limit filtration membrane") and is then returned to the 15t RO water tank.

[0043] (Related to RO module recovery) Furthermore, as shown in Figure 1, the water treatment apparatus 10 of this embodiment includes a recovery RO module 31 that separates RO wastewater into return water and non-recoverable wastewater using a reverse osmosis membrane, and a recovery RO pump 32 that sends RO wastewater to the recovery RO module 31.

[0044] An RO drain channel 33, extending from RO module 14m and equipped with a first drain adjustment valve 34 along its length, is configured to guide RO wastewater to the recovery RO pump 32. Additionally, a non-recovery drain channel 35 extends from recovery RO module 31, guiding non-recovery wastewater to a drain outlet 36. A second drain adjustment valve 39 and a non-recovery wastewater volume sensor 40 are provided along the non-recovery drain channel 35. On the other hand, a recovery channel 41 extends from recovery RO module 31 for reusing the RO membrane-treated return water and is connected to either the raw water tank 11 or the RO water tank 15t via a switching valve 42.

[0045] In the water treatment device 10 shown in Figure 1, the amount of return water generated in the recovery RO module 31 is detected by a return water volume sensor 38, and the recovery RO pump 32 is controlled based on the detection result of the return water volume sensor 38 (inverter control).

[0046] Specifically, when the detection result from the return water volume sensor 38 is greater than the target set water volume (for example, set and input by the user to the control unit 30 via a touch panel, etc.), the inverter value of the recovery RO pump 32 is reduced by a predetermined amount (for example, 0.3%) at predetermined time intervals (for example, 0.5 seconds). Conversely, when the detection result from the return water volume sensor 38 is smaller than the target set water volume, the inverter value of the recovery RO pump 32 is increased by a predetermined amount (for example, 0.5%) at predetermined time intervals (for example, 1.0 second).

[0047] Furthermore, in the water treatment device 10 shown in Figure 1, in order to ensure stable operation of the recovery RO pump 32, the pressure of the RO wastewater supplied to the recovery RO pump 32 must be above a predetermined pressure (for example, 0.10 MPa or higher).

[0048] Here, the operating state of the RO module 14m fluctuates depending on the desired amount of RO water produced (which may be set according to the water level in the RO water tank 15t, or as desired), and the amount of RO wastewater guided through the RO drainage channel 33 also fluctuates accordingly.

[0049] In the water treatment device 10 shown in Figure 1, the opening degree of the first drainage adjustment valve 34 is automatically controlled to ensure that the pressure of the RO wastewater sent to the recovery RO pump 32 (monitored by a pressure sensor 37 near the inlet of the recovery RO pump 32) is always above a predetermined pressure, and to suppress fluctuations in that pressure to a minimum, in response to such fluctuations in the amount of RO wastewater (this control is performed preferentially by the control unit 30 over other coordinated controls).

[0050] Specifically, when the detection result from the pressure sensor 37 is greater than the target set pressure (for example, set and input by the user to the control unit 30 via a touch panel, etc., and is, for example, 0.15 MPa), the opening degree of the first drain adjustment valve 34 is reduced by a predetermined amount (for example, 0.5%: a relative value where fully closed is 0% and fully open is 100%) at predetermined time intervals (for example, 1.0 second). Conversely, when the detection result from the pressure sensor 37 is smaller than the target set pressure, the opening degree of the first drain adjustment valve 34 is increased by a predetermined amount (for example, 0.5%) at predetermined time intervals (for example, 1.0 second).

[0051] Furthermore, in the water treatment device 10 shown in Figure 1, the opening degree of the second wastewater adjustment valve 39 is automatically controlled based on a preset target recovery rate in order to maintain the recovery rate (wastewater recovery membrane recovery rate) in the recovery RO module 31 at a substantially constant value.

[0052] Specifically, when the recovery rate at that time point is greater compared to the target recovery rate (for example, set and input to the control unit 30 by the user via a touch panel or the like, and for example, 65%), the opening degree of the second drainage adjustment valve 39 is increased by a predetermined amount (for example, 0.5%: a relative value with fully closed being 0% and fully open being 100%) every predetermined time interval (for example, 1.0 seconds). Conversely, when the recovery rate at that time point is smaller compared to the target recovery rate, the opening degree of the second drainage adjustment valve 39 is reduced by a predetermined amount (for example, 0.5%) every predetermined time interval (for example, 1.0 seconds). The recovery rate at that time point is calculated by the control unit 30 according to the arithmetic formula: (detection result by the return water volume sensor 38) / ((detection result by the return water volume sensor 38) + (detection result by the non-recovered drainage volume sensor 40) × 100).

[0053] In addition, in the water treatment apparatus 10 shown in FIG. 1, a raw water drainage path that extends from the upstream side of the RO module 14m and guides raw water to the RO drainage path 33 is further provided, and a raw water drainage valve 43 is provided in the middle of the raw water drainage path.

[0054] (Operation) Next, the operation of this embodiment will be described.

[0055] As shown in FIG. 1, raw water, which is tap water at, for example, 14°C, is stored in the raw water tank 11. Then, the heating heater 11h of the raw water tank 11 further heats the temperature of the raw water to 25°C.

[0056] The raw water heated to 25°C is sent to the pretreatment unit 13 by the raw water pump 12. In the pretreatment unit 13, the pre-filter 13a mainly filters and removes impurities (dust) in the raw water, the water softening device 13b mainly removes calcium ions (Ca 2+ ) and magnesium ions (Mg 2+ ) in the raw water, and the carbon filter 13c mainly removes residual chlorine (total chlorine: free chlorine + combined chlorine) in the raw water.

[0057] After pretreatment in the pretreatment unit 13, the raw water is sent to the RO unit 14 (reverse osmosis membrane treatment device). The RO unit 14 uses the RO pump 14p to supply the pretreated raw water into the RO module 14m. The RO module 14m performs treatment to remove all inorganic ions contained in the raw water, and the RO water that has been treated in the RO module 14m is sent to the RO water supply unit 15.

[0058] On the other hand, of the RO wastewater generated by the treatment in RO module 14m, a portion (also called "recirculating water") is reintroduced into RO module 14m via RO pump 14p, while another portion (approximately 30-50% of the raw water, also called "concentrated water") is treated as wastewater.

[0059] In this embodiment, the control unit 30 coordinately controls the RO pump 14p and the first drain adjustment valve 34 so that a desired amount of RO water is generated and a desired drain pressure (pressure detected by the pressure sensor 37 (drain recovery pump inlet pressure)) of the RO module 14m is achieved (however, the control of the first drain adjustment valve 34, which will be described later, takes precedence).

[0060] In the RO water supply unit 15, RO water is stored in the RO water tank 15t. If necessary, UV irradiation treatment is performed by the UV irradiation device 15u.

[0061] Subsequently, the RO water stored in the RO water tank 15t is sent to the UF17 (ultrafilter) via the water pump 16. The UF17 removes biological impurities from the RO water. The RO water, from which biological impurities have been removed by the UF17, is sent to various medical devices (not shown) for dialysis treatment, for example, as dialysis water. After circulating through the medical devices, this dialysis water returns to the UF18 (ultrafilter) and is then returned to the RO water tank 15t.

[0062] Meanwhile, the amount of return water generated in the recovery RO module 31 is detected by the return water volume sensor 38, and the recovery RO pump 32 is controlled based on the detection result of the return water volume sensor 38 (inverter control).

[0063] Specifically, when the detection result from the return water volume sensor 38 is greater than the target set water volume, the inverter value of the recovery RO pump 32 is reduced by a predetermined amount at predetermined time intervals. Conversely, when the detection result from the return water volume sensor 38 is smaller than the target set water volume, the inverter value of the recovery RO pump 32 is increased by a predetermined amount at predetermined time intervals.

[0064] Furthermore, the opening of the first drainage adjustment valve 34 is automatically controlled to ensure that the pressure of the RO wastewater sent to the recovery RO pump 32 is always above a predetermined pressure, and to suppress fluctuations in that pressure (this control is performed preferentially over other coordinated controls).

[0065] Specifically, when the detection result from the pressure sensor 37 is greater than the target set pressure, the opening degree of the first drain adjustment valve 34 is reduced by a predetermined amount at predetermined time intervals. Conversely, when the detection result from the pressure sensor 37 is smaller than the target set pressure, the opening degree of the first drain adjustment valve 34 is increased by a predetermined amount at predetermined time intervals.

[0066] Furthermore, in order to maintain the recovery rate (wastewater recovery membrane recovery rate) in the recovery RO module 31 at a nearly constant value, the opening degree of the second wastewater adjustment valve 39 is automatically controlled based on a preset target recovery rate.

[0067] Specifically, when the recovery rate at a given time is greater than the target recovery rate, the opening of the second drainage control valve 39 is increased by a predetermined amount at predetermined time intervals. Conversely, when the recovery rate at a given time is less than the target recovery rate, the opening of the second drainage control valve 39 is decreased by a predetermined amount at predetermined time intervals.

[0068] (effect) With the water treatment device 10 described above, in addition to the recovery RO pump 31 being controlled based on the detection result of the return water volume sensor 38, the first drain adjustment valve 34 is controlled based on the detection result of the pressure sensor 37, and the second drain adjustment valve 39 is controlled based on a preset target recovery rate. This makes it possible to maintain the recovery rate (wastewater recovery membrane recovery rate) in the recovery RO module 31 at a substantially constant value, and consequently improve the overall system recovery rate of the water treatment device 10.

[0069] In particular, the water treatment device 10 in Figure 1 includes an RO pump 14p that supplies raw water to the RO module 14m, and an RO water volume sensor 15s that detects the amount of RO water produced in the RO module 14m. The RO pump 14p is controlled based on the detection result of the RO water volume sensor 15s.

[0070] In this embodiment, the amount of RO wastewater led from the RO module 14m by the RO drain channel 33 fluctuates depending on the amount of RO water generated (which can be set according to the water level in the RO water tank, or as desired). However, according to this embodiment, despite (and absorbing) such fluctuations in the amount of RO wastewater, it is possible to maintain the recovery rate (wastewater recovery membrane recovery rate) in the recovery RO module 31 at a substantially constant value.

[0071] Specifically, as shown in the table in Figure 2 as an example, the water treatment device 10 shown in Figure 1 ensures that the pressure of the RO wastewater at the inlet of the recovery RO pump 32 (monitored by the pressure sensor 37) is at a predetermined pressure (e.g., 0.1 MPa or higher), and that fluctuations in this pressure are kept small.

[0072] Furthermore, the recovery RO pump 32 is inverter-controlled based on the detection result of the return water volume sensor 38, and the second drain adjustment valve 39 is controlled based on a preset target recovery rate, so that the recovery rate (wastewater recovery membrane recovery rate) in the recovery RO module 31 stabilizes at 65.6% (within 65% ± 1%).

[0073] At this time, the detection result of the return water volume sensor 38 was within the range of 6.3 to 11.3 L / min, and the wastewater flow rate (wastewater recovery RO wastewater flow rate) flowing from the non-recovery drainage channel 35 to the drain outlet 36 was within the range of 3.3 to 5.9 L / min. Also at this time, the flow rate of RO water generated by the RO module 14m (RO treated water flow rate) was 21.2 to 39.8 L / min, the recovery rate in the RO module 14m (RO membrane recovery rate) was 67.9 to 69.3%, and the overall system recovery rate of the water treatment device was 86.5 to 87.0%. Comparing the lower limits, it can be seen that there has been an improvement of 3% compared to the comparative example.

[0074] In addition, in the water treatment device 10 shown in Figure 1, the return water from the recovery RO module 31 is selectively returned to the raw water tank 11 or to the RO water tank 15t via a switching valve 42. Therefore, in emergencies such as when the RO module malfunctions and RO water cannot be generated, the return water (recovered RO membrane treated water) can be used as dialysis water.

[0075] Furthermore, in the water treatment device 10 shown in Figure 1, a raw water drainage channel is provided that extends from the upstream side of the RO module 14m and guides raw water to the RO drainage channel 33. Therefore, in emergencies such as when the RO module malfunctions and RO water cannot be produced, raw water can be guided to a recovery RO module as an alternative treatment to the RO module, and the return water (recovered RO membrane treated water) from the recovery RO module can be used as dialysis water. [Explanation of symbols]

[0076] 10 Water treatment equipment 11 Raw water tank 11h heating heater 12 Raw water pump 13 Pre-processing unit 13a Pre-filter 13b Water softener 13c carbon filter 14 RO units 14m RO module 14p RO pump 15 RO water supply unit 15f Air Filter 15s RO water volume sensor 15t RO water tank 15u UV irradiation device 16 Water supply pump 17 Ultrafiltration membrane (UF) for water supply 18. Return ultrafiltration membrane (UF) 22 Branching point 23 Circulation route 24. Circulation water volume control valve 30 Control Panel 31 RO recovery module 32 RO recovery pump 33 RO drain 34. First drainage adjustment valve 35 Non-recoverable drainage channels 36 Drain 37 Pressure Sensor 38. Return water volume sensor 39. Second drainage adjustment valve 40 Unrecovered wastewater volume sensor 41 Recovery Route 42 Diverter valve 43. Valve for raw water drainage 51 Raw water tank 51h heating element 52 Raw water pump 53 Pre-processing unit 53a Pre-filter 53b Water softener 53c carbon filter 54 RO units 54m RO module 54p RO Pump 55 RO water supply unit 55f Air Filter 55t RO water tank 55u UV irradiation device 56 Water supply pump 57. Ultrafiltration membrane (UF) for water supply 58. Return ultrafiltration membrane (UF) 61 RO Recovery Module 62 RO recovery pump 63 RO Drainage Channel 64. First drainage adjustment valve 65 Non-recoverable drainage channels 66 Drain 67 Pressure Sensor 68 Return water volume sensor

Claims

1. An RO module that separates raw water into RO water and RO wastewater using a reverse osmosis membrane, A recovery RO module that separates the RO wastewater into return water and non-recoverable wastewater using a reverse osmosis membrane, A recovery RO pump that sends the RO wastewater to the recovery RO module, An RO drainage channel extending from the RO module and leading the RO wastewater to the RO recovery pump, A pressure sensor for detecting the pressure of the RO wastewater being sent to the RO recovery pump, A return water volume sensor for detecting the amount of return water generated in the RO recovery module, A first drainage adjustment valve is installed in the middle of the aforementioned RO drainage channel, A non-recovery drainage channel extending from the RO recovery module and leading the non-recovery wastewater to the drain outlet, A second drainage adjustment valve is installed in the middle of the aforementioned non-recoverable drainage channel, Equipped with, The RO recovery pump is controlled based on the detection result of the return water volume sensor. The first drain adjustment valve is controlled based on the detection result of the pressure sensor. The second drainage control valve is controlled based on a preset target recovery rate. A water treatment apparatus characterized by the following:

2. An RO pump that supplies the raw water to the RO module, An RO water volume sensor for detecting the amount of RO water generated in the RO module, Furthermore, The RO pump is controlled based on the detection result of the RO water volume sensor. The water treatment apparatus according to feature 1.

3. A raw water tank for storing the raw water is provided upstream of the RO module. An RO tank for storing the RO water is provided downstream of the RO module. The return water is selectively returned to either the raw water tank or the RO tank. The water treatment apparatus according to claim 1 or 2.

4. A raw water drainage channel extending from the upstream side of the RO module and leading raw water to the RO drainage channel. The water treatment apparatus according to claim 1 or 2.

5. A raw water drainage channel extending from the upstream side of the RO module and leading raw water to the RO drainage channel. The water treatment apparatus according to claim 3.

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