Water treatment device and water treatment method

Abstract

To provide a water treatment device and a water treatment method capable of maintaining the quality of water to be treated while sufficiently using the heat of the underground water.SOLUTION: A water treatment device 100 comprises a main route 1 guiding water to be treated i.e., the underground water, a heat exchanger 3 exchanging heat with the water to be treated, a membrane treatment unit 6 membrane-treating the water to be treated having passed through the heat exchanger 3, a thermometer 5 measuring the temperature of the water to be treated between the heat exchanger 3 and the membrane treatment unit 6, and a controller 7 controlling the flow rate of the water to be treated. The heat exchanger 3 comprises a circulation route 21 guiding at least a portion of the water to be treated present in the main route 1 as circulating water, a heat exchanger 22 exchanging heat with the circulating water, and a return route 23 returning the circulating water having passed through the heat exchanger 22 to the main route 1. The controller 7 controls the flow rate of the circulating water according to the measurement value of the thermometer 5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a water treatment device and a water treatment method. [Background technology]

[0002] Conventionally, heat utilization systems that utilize groundwater have been used. This type of heat utilization system includes, for example, a heat exchanger, a tank, and a circulation passage. The heat exchanger uses groundwater as a heat source. The tank stores the groundwater discharged from the outlet of the heat exchanger. The circulation passage circulates the groundwater in the tank to the inlet of the heat exchanger (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Utility Model Registration No. 3219818 [Patent Document 2] Patent Publication No. 2021-113662 Summary of the Invention [Problem to be solved by the invention]

[0004] In a heat utilization system employing a circulating heat exchanger such as that described in Patent Document 1, heat is removed from groundwater, which can cause a drop in the groundwater temperature. In this heat utilization system, if a membrane device is installed downstream of the circulation passage to produce purified water such as drinking water, the temperature of the membrane supply water will fluctuate depending on the outside air temperature, and the membrane rejection rate will also fluctuate, which can have a negative impact on the quality of the treated water.

[0005] An example of a water treatment device that utilizes the heat of groundwater and purifies the groundwater is the device described in Patent Document 2. Patent Document 2 discloses that a one-pass system is used. This water treatment device is advantageous in improving the quality of treated water because it can suppress temperature fluctuations in the groundwater, but there are cases where the heat of the groundwater cannot be fully utilized.

[0006] An object of one aspect of the present invention is to provide a water treatment device and a water treatment method that can ensure the quality of treated water while fully utilizing the heat of groundwater. [Means for solving the problem]

[0007] In view of the above problems, the inventors discovered that the above problems can be solved by circulating the water to be treated and heat exchanging it so that the temperature of the water to be treated supplied to the membrane treatment is within the allowable temperature range of the membrane treatment, and thus completed the present invention.

[0008] [1] A water treatment device for purifying groundwater, a main path through which the groundwater is guided as water to be treated; A heat exchange unit that performs heat exchange of the water to be treated; a membrane treatment unit that performs membrane treatment on the water to be treated that has passed through the heat exchange unit; a thermometer for measuring the temperature of the water to be treated between the heat exchange unit and the membrane treatment unit; a control unit for controlling the flow rate of the water to be treated, The heat exchange unit is a circulation path that guides at least a portion of the water to be treated in the main path as circulating water; a heat exchanger that exchanges heat with the circulating water; a return path that returns the circulating water that has passed through the heat exchanger to the main path, The control unit controls the flow rate of the circulating water based on the measurement value of the thermometer. Water treatment equipment. [2] A circulation pump is provided in the circulation path to send the circulating water to the heat exchanger, The water treatment device according to [1], wherein the control unit reduces the flow rate of the circulating water by reducing the output of the circulating pump when the measurement value of the thermometer falls outside the allowable temperature range of the membrane treatment unit. [3] A circulation valve that opens and closes the circulation path is provided in the circulation path, The water treatment device according to [1], wherein the control unit reduces the flow rate of the circulating water by reducing the opening of the circulation valve when the measurement value of the thermometer falls outside the allowable temperature range of the membrane treatment unit. [4] The water treatment device according to any one of [1] to [3], further comprising a storage section for storing the water to be treated that is to be guided to the heat exchange section. [5] The water treatment device according to any one of [1] to [4], further comprising a pre-treatment section that pre-treats the water to be treated, located upstream of the membrane treatment section. [6] A water treatment method for purifying groundwater, comprising: a heat exchange step of introducing the groundwater as water to be treated and performing heat exchange on the water to be treated; a membrane treatment step of performing membrane treatment on the water to be treated that has undergone the heat exchange step, In the heat exchange step, at least a portion of the water to be treated is guided as circulating water through a circulation path, and heat exchange of the circulating water is performed using a heat exchanger. Then, the circulating water that has passed through the heat exchanger is returned. measuring the temperature of the water to be treated between the heat exchange step and the membrane treatment step; The water treatment method further comprises controlling the flow rate of the circulating water based on the measured temperature. [7] A circulation pump is provided in the circulation path to send the circulating water to the heat exchanger, [6] A water treatment method according to [6], wherein, when controlling the flow rate of the circulating water, if the measured temperature value falls outside the allowable temperature range of the membrane treatment, the flow rate of the circulating water is reduced by reducing the output of the circulating pump. [8] A circulation valve that opens and closes the circulation path is provided in the circulation path, [6] A water treatment method according to [6], wherein, when controlling the flow rate of the circulating water, if the measured temperature value falls outside the allowable temperature range of the membrane treatment, the flow rate of the circulating water is reduced by reducing the opening of the circulation valve. [9] The water treatment method according to any one of [6] to [8], further comprising a preliminary measurement step of determining an allowable temperature range for the membrane treatment by measuring the relationship between the temperature of the water to be treated and the rejection rate of the membrane treatment prior to the heat exchange step. [Effects of the Invention]

[0009] According to one aspect of the present invention, it is possible to provide a water treatment device and a water treatment method that can ensure the quality of treated water while fully utilizing the heat of groundwater. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of a water treatment device according to a first embodiment. [Figure 2] FIG. 10 is a schematic diagram of a water treatment device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] The treatment target of the water treatment device and water treatment method of the embodiments is groundwater. The groundwater is pumped up from, for example, a deep well. A deep well is, for example, a well that uses groundwater from a confined aquifer. The groundwater can be, for example, groundwater from 10 to 200 meters underground. The temperature of groundwater pumped up from a deep well varies depending on the region, but in Japan it is generally, for example, 15 to 18°C, with an annual temperature difference of less than 2°C. In other words, the "groundwater" in this document is groundwater that satisfies one or more of the following conditions: - Groundwater with a year-round temperature of 15-18°C Groundwater with an annual temperature difference of less than 2°C Groundwater pumped from a confined aquifer 10m to 200m below ground

[0012] Groundwater may contain impurities such as organic matter, ammonia nitrogen, anions such as bicarbonate ions, nitrate ions, sulfate ions, and chloride ions; cations such as iron ions, manganese ions, calcium ions, and magnesium ions; and bacteria.

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0014] First Embodiment [Water treatment equipment] FIG. 1 is a schematic diagram of a water treatment device 100 according to the first embodiment. 1, the water treatment device 100 includes a main path 1, a pretreatment section 2, a heat exchange section 3, a storage section 4, a thermometer 5, a membrane treatment section 6, a control section 7, a posttreatment section 8, a circulation pump 9, and a circulation valve 10. The water treatment device 100 is a device for purifying groundwater.

[0015] The main path 1 is a pipe that pumps up groundwater from a well 20 and guides the pumped groundwater as water to be treated W1. The pretreatment section 2 includes a raw water tank 11 , a clarification section 12 , and an adsorption section 13 .

[0016] The raw water tank 11 stores the water to be treated W1. The clarification unit 12 removes turbid components (e.g., solid substances) from the water to be treated W1. The clarification unit 12 is, for example, a filtration device filled with filter media. The clarification unit 12 is, for example, a sand filtration tank using sand as the filter media. The water to be treated W1 that has passed through the clarification unit 12 is called clarified water W2.

[0017] The adsorption unit 13 adsorbs and removes organic matter, inorganic matter (residual chlorine, metals, metal compounds, etc.) contained in the clarified water W2 (water to be treated). The adsorption unit 13 is, for example, an adsorption device filled with an adsorbent. Examples of adsorbents include activated carbon, ion exchange resins, and natural product adsorbents (zeolite, etc.). The clarified water W2 that has passed through the adsorption unit 13 is referred to as adsorption-treated water W3 (water to be treated). The pretreatment unit 2 may include a water quality adjustment unit (a pH adjustment unit, a hypochlorite addition unit, etc.).

[0018] The heat exchange unit 3 performs heat exchange on the adsorption treated water W3. The heat exchange unit 3 has a circulation path 21, a heat exchanger 22, and a return path . The circulation path 21 is a pipe provided branching off from the main path 1. The circulation path 21 guides at least a portion of the adsorption-treated water W3 in the reservoir 4 to the heat exchanger 22 as circulating water W6 (water to be treated).

[0019] The heat exchanger 22 may be, for example, a groundwater cooler, an outdoor unit of an air conditioner, a heat pump, a fan coil, or a chiller (cooling water circulation device). A heat exchanger used in an air conditioner is preferable as the heat exchanger 22. The heat exchanger 22 exchanges heat with the circulating water W6. The heat exchanger 22 can utilize the heat of the circulating water W6 by exchanging heat between the circulating water W6 and a heat medium or a cooling medium, for example, air.

[0020] The return path 23 connects the heat exchanger 22 and the main path 1. The return path 23 returns the circulating water W6 that has passed through the heat exchanger 22 to the main path 1 as returned water W7 (water to be treated).

[0021] The storage section 4 is provided on the main path 1. The storage section 4 stores the adsorption-treated water W3 (water to be treated) on the main path 1. The storage section 4 has a function of ensuring the amount of adsorption-treated water W3 (water to be treated) to be guided to the heat exchanger 22. The storage section 4 is a so-called cushion tank.

[0022] The thermometer 5 (water temperature gauge) is provided in the main path 1 at a position between the reservoir 4 and the membrane treatment section 6. The thermometer 5 measures the temperature of the adsorption-treated water W3 in the main path 1.

[0023] The membrane treatment unit 6 performs membrane treatment on the adsorption-treated water W3. The membrane treatment unit 6 treats the adsorption-treated water W3 using a separation membrane to obtain membrane-treated water W4. The membrane-treated water W4 is permeate that has permeated the separation membrane. Examples of separation membranes that can be used include ultrafiltration membranes (UF membranes), microfiltration membranes (MF membranes), nanofiltration membranes (NF membranes), and reverse osmosis membranes (RO membranes). Examples of the form of the separation membrane include spiral membranes, hollow fiber membranes, tubular membranes, and flat membranes. Examples of materials for the separation membrane include polyamide, polysulfone, cellulose acetate, and polyacrylonitrile.

[0024] The control unit 7 controls the flow rate of the circulating water W6 based on the measurement value of the thermometer 5. The control unit 7 can control the operation of at least one of the circulation pump 9 and the circulation valve 10. The control unit 7 can, for example, control the output of the circulation pump 9 based on the measurement value of the thermometer 5. The control unit 7 can, for example, control the opening degree of the circulation valve 10 based on the measurement value of the thermometer 5.

[0025] The control unit 7 may be linked to a remote monitoring system. For example, using equipment such as a PC or mobile terminal, the measurement value of the thermometer 5, the flow rate of the circulating water W6, and the status of the circulation pump 9 and circulation valve 10 are monitored remotely. If the measurement value of the thermometer 5 exceeds a preset upper temperature limit, the control unit 7 issues an alarm and stops the circulation pump 9 or closes the circulation valve 10, thereby reducing the circulating water flow rate to zero.

[0026] The post-treatment unit 8 adds a hypochlorite such as sodium hypochlorite to the membrane-treated water W4. The membrane-treated water W4 becomes treated water W5 by adding the hypochlorite.

[0027] The circulation pump 9 and the circulation valve 10 are provided in the circulation path 21 . The circulation pump 9 sends the circulation water W6 to the heat exchanger 22. The circulation pump 9 can determine the flow rate of the circulation water W6 flowing through the circulation path 21 by adjusting the output. The circulation valve 10 can freely open and close the flow path of the circulation path 21. The circulation valve 10 can determine the flow rate of the circulating water W6 flowing through the circulation path 21 by adjusting the opening degree.

[0028] [Water treatment method] The water treatment method according to the first embodiment is a water treatment method using a water treatment device 100 shown in FIG. The water treatment method of this embodiment includes a pretreatment step, a heat exchange step, a membrane treatment step, and a posttreatment step. The water treatment method of this embodiment is a method for purifying groundwater.

[0029] (Pretreatment process) Groundwater is pumped up from a well 20 through a main path 1. The pumped up groundwater is led to a raw water tank 11 as water to be treated W1. The water to be treated W1 in the raw water tank 11 is led to a clarification section 12. In the clarification section 12, turbid components (e.g., solid substances) in the water to be treated W1 are removed, and clarified treated water W2 (water to be treated) is obtained.

[0030] The clarified water W2 is introduced into the adsorption section 13. In the adsorption section 13, organic matter and inorganic matter (residual chlorine, metals, metal compounds, etc.) contained in the clarified water W2 are adsorbed and removed to obtain adsorption-treated water W3 (water to be treated). The adsorption-treated water W3 is introduced into the storage section 4.

[0031] (Heat exchange process) The adsorption-treated water W3 in the reservoir 4 is guided through a circulation path 21 to a heat exchanger 22 as circulating water W6 (water to be treated). The heat exchanger 22 exchanges heat with the circulating water W6. The heat exchanger 22 can utilize the heat of the circulating water W6, for example, by exchanging heat between the circulating water W6 and a heating medium or a cooling medium (e.g., air). The circulating water W6 that has passed through the heat exchanger 22 is returned to the main path 1 through a return path 23 as returned water W7 (water to be treated).

[0032] In this process, the control unit 7 controls the flow rate of the circulating water W6 based on the measurement value of the thermometer 5. At least one of the circulation pump 9 and the circulation valve 10 can be used to control the flow rate of the circulating water W6. As mentioned above, the control unit 7 may be linked to a remote monitoring system. For example, using equipment such as a PC or mobile terminal, the measurement value of the thermometer 5, the flow rate of the circulating water W6, and the status of the circulation pump 9 and the circulation valve 10 are monitored remotely. If the measurement value of the thermometer 5 exceeds a preset upper temperature limit, the control unit 7 issues an alarm and stops the circulation pump 9 or closes the circulation valve 10, thereby reducing the circulating water flow rate to zero.

[0033] When using the circulation pump 9, the following method can be used: When the measurement value of the thermometer 5 is outside the allowable temperature range of the membrane treatment unit 6, the control unit 7 reduces the output of the circulation pump 9, thereby reducing the flow rate of the circulating water W6. When the measurement value of the thermometer 5 is within the allowable temperature range of the membrane processing unit 6, the control unit 7 does not need to adjust the output of the circulating pump 9. When the measurement value of the thermometer 5 is within the allowable temperature range of the membrane processing unit 6, the control unit 7 may adjust the output of the circulating pump 9 depending on the capacity of the circulating pump 9.

[0034] When the circulation valve 10 is used, the following method can be used: When the measurement value of the thermometer 5 is outside the allowable temperature range of the membrane treatment section 6, the control section 7 reduces the opening of the circulation valve 10 to reduce the flow rate of the circulating water W6. When the measurement value of the thermometer 5 is within the allowable temperature range of the membrane processing unit 6, the control unit 7 does not need to adjust the opening of the circulation valve 10. When the measurement value of the thermometer 5 is within the allowable temperature range of the membrane processing unit 6, the control unit 7 may adjust the opening of the circulation valve 10 depending on the capacity of the circulation pump 9.

[0035] An example of a control method by the control unit 7 is given below. (i) First control example When the measurement value of the thermometer 5 is within the allowable temperature range of the membrane treatment unit 6 (e.g., above 5°C and below 25°C), the control unit 7 circulates at least a portion of the adsorption-treated water W3 through the heat exchange unit 3 and performs heat exchange in the heat exchanger 22. If the measurement value of the thermometer 5 is outside the allowable temperature range of the membrane processing unit 6 (for example, below 5°C or above 25°C), the control unit 7 will not circulate the circulating water W6 using the heat exchange unit 3.

[0036] (i) Second control example The control unit 7 controls the flow rate of the circulating water W6 so that the measurement value of the thermometer 5 falls within the allowable temperature range of the membrane processing unit 6. The control unit 7 adjusts, for example, the output of the circulating pump 9 or the opening of the circulating valve 10 so that the temperature falls within the allowable temperature range of the membrane processing unit 6.

[0037] (Membrane treatment process) The adsorption-treated water W3 (water to be treated) in the reservoir 4 is guided to the membrane treatment section 6. In the membrane treatment section 6, the adsorption-treated water W3 is treated using a separation membrane to obtain membrane-treated water W4.

[0038] (Post-processing process) A hypochlorite such as sodium hypochlorite is added to the membrane-treated water W4 by the post-treatment unit 8. The membrane-treated water W4 becomes treated water W5 by adding the hypochlorite.

[0039] The allowable temperature range of the membrane treatment unit 6 can be determined by the following preliminary measurement step. The preliminary measurement step can be performed prior to the pretreatment step. That is, the water treatment method of the embodiment may include a preliminary measurement step, a pretreatment step, a heat exchange step, a membrane treatment step, and a posttreatment step.

[0040] In this specification, the "allowable temperature range of the membrane processing section" refers to the operating temperature range of the separation membrane in the membrane processing section, i.e., the temperature range of the membrane supply water (water supplied to the separation membrane) that can maintain the performance (e.g., rejection) of the separation membrane.

[0041] The allowable temperature range of the membrane treatment section 6 can be determined by measuring the relationship between the temperature of the membrane feed water and the rejection rate of the membrane treatment in the membrane treatment section 6. For example, the allowable temperature range of the membrane treatment section (the operating temperature range of the separation membrane) can be determined from the following perspectives. i) The correlation between the temperature of the membrane feed water and the rejection rate as specified by the membrane manufacturer. ii) The temperature of the membrane supply water corresponding to the rejection rate obtained according to the quality of the treated water required when applied to a water treatment device. iii) The temperature of the membrane feed water, which is set taking into account practical issues when providing treated water.

[0042] Regarding i) and ii) above, when the temperature of the water to be treated is within the temperature range allowed by the membrane treatment unit 6, the pore size of the separation membrane is within the appropriate range. The viscosity of the water is relatively low. As a result, the resistance to water flow through the separation membrane is low. This allows the water to be properly treated through the membrane. In contrast, when the temperature of the water to be treated falls below the temperature allowed by the membrane treatment unit 6, the pore size of the separation membrane becomes smaller. The viscosity of the water becomes higher. As a result, the resistance to water flow through the separation membrane becomes higher. When the temperature of the water to be treated exceeds the temperature allowed by the membrane treatment unit 6, the pore size of the separation membrane becomes larger, and the performance of removing impurities decreases.

[0043] Regarding the above-mentioned iii), considering the quality of the treated water, for example, if the treated water meets the 51-item (tap water) standard, it is preferable to set the upper limit temperature to the temperature of tap water. Also, to avoid freezing problems, it is preferable to set the lower limit of the allowable temperature range for the membrane treatment section to 5°C.

[0044] [Effects of the water treatment device and water treatment method according to the first embodiment] In the water treatment device 100 of this embodiment, the control unit 7 controls the flow rate of the circulating water W6 based on the measurement value of the thermometer 5. By controlling the flow rate of the circulating water W6, the amount of heat exchanged in the heat exchanger 22 increases or decreases. Therefore, the temperature of the water to be treated introduced into the membrane treatment unit 6 can be kept within the temperature range allowed by the membrane treatment unit 6. This makes it possible to improve the treatment performance of the membrane treatment unit 6. Therefore, the quality of the treated water W5 can be ensured.

[0045] In the water treatment device 100, the circulating water W6 is circulated in the heat exchange section 3, and therefore the heat of the circulating water W6, which is groundwater, can be fully utilized in the heat exchanger 22.

[0046] In the water treatment device 100, a circulation pump 9 is provided in the circulation path 21. When the measurement value of the thermometer 5 is outside the allowable temperature range of the membrane treatment device 6, the control unit 7 can reduce the output of the circulation pump 9 to reduce the flow rate of the circulating water W6. Therefore, the water treatment device 100 can accurately control the flow rate of the circulating water W6 with a simple configuration.

[0047] In the water treatment device 100, a circulation valve 10 is provided in the circulation path 21. When the measurement value of the thermometer 5 is outside the allowable temperature range of the membrane treatment device 6, the control unit 7 can reduce the flow rate of the circulating water W6 by reducing the opening of the circulation valve 10. Therefore, the water treatment device 100 can accurately control the flow rate of the circulating water W6 with a simple configuration.

[0048] The water treatment device 100 includes the reservoir 4, so that the amount of water to be treated can be secured, and therefore the water to be treated can be stably treated.

[0049] The water treatment device 100 includes a pretreatment unit 2 that pretreats the water to be treated, thereby improving the quality of the treated water W5.

[0050] According to the water treatment method of this embodiment, in the heat exchange step, the flow rate of the circulating water W6 is controlled based on the measured temperature of the adsorption-treated water W3 (water to be treated). By controlling the flow rate of the circulating water W6, the amount of heat exchanged in the heat exchanger 22 increases or decreases. Therefore, the temperature of the water to be treated introduced into the membrane treatment unit 6 can be kept within the temperature range allowed by the membrane treatment unit 6. This makes it possible to improve the treatment performance of the membrane treatment unit 6. Therefore, the quality of the treated water W5 can be ensured.

[0051] In the water treatment method, the circulating water W6 is circulated in the heat exchange section 3, and therefore the heat of the circulating water W6, which is groundwater, can be fully utilized in the heat exchanger 22.

[0052] In the water treatment method, if the measurement value of the thermometer 5 is outside the allowable temperature range of the membrane treatment in the heat exchange step, the flow rate of the circulating water W6 can be reduced by lowering the output of the circulating pump 9. Therefore, the flow rate of the circulating water W6 can be accurately controlled with a simple configuration.

[0053] In the water treatment method, if the measurement value of the thermometer 5 is outside the allowable temperature range of the membrane treatment in the heat exchange step, the flow rate of the circulating water W6 can be reduced by reducing the opening of the circulation valve 10. Therefore, the flow rate of the circulating water W6 can be accurately controlled with a simple configuration.

[0054] In the water treatment method, a preliminary measurement step may be carried out prior to the heat exchange step, thereby making it possible to properly determine the allowable temperature range for membrane treatment.

[0055] <Second embodiment> [Water treatment equipment] FIG. 2 is a schematic diagram of a water treatment device 200 according to the second embodiment. 2, the water treatment device 200 includes a main path 1, a pretreatment section 202, a heat exchange section 3, a storage section 4, a thermometer 5, a membrane treatment section 6, a control section 7, a posttreatment section 8, a circulation pump 9, and a circulation valve 10. Components common to the water treatment device 100 according to the first embodiment are designated by the same reference numerals, and descriptions thereof will be omitted.

[0056] The pretreatment unit 202 includes a raw water tank 11, a clarification unit 12, and an adsorption unit 13. The raw water tank 11 and the clarification unit 12 are provided in the same positions as the raw water tank 11 and the clarification unit 12 in the water treatment device 100 (see FIG. 1). The adsorption unit 13 is provided in a position between the thermometer 5 and the membrane treatment unit 6. Except for the adsorption unit 13, the water treatment device 200 may have the same configuration as the water treatment device 100 (see FIG. 1).

[0057] [Water treatment method] The water treatment method according to the second embodiment is a water treatment method using a water treatment device 200 shown in FIG. The water treatment method of this embodiment includes a first pretreatment step, a heat exchange step, a second pretreatment step, a membrane treatment step, and a post-treatment step.

[0058] (First pretreatment step) Groundwater is introduced into raw water tank 11 as water to be treated W1. The water to be treated W1 in raw water tank 11 is introduced into clarification section 12. In clarification section 12, turbid components (e.g., solid substances) in the water to be treated W1 are removed to obtain clarified water W2 (water to be treated). The clarified water W2 is introduced into storage section 4.

[0059] (Heat exchange process) The clarified water W2 in the reservoir 4 is guided through a circulation path 21 to a heat exchanger 22 as circulating water W6. The heat exchanger 22 performs heat exchange of the circulating water W6. The heat exchanger 22 can utilize the heat of the circulating water W6, for example, by exchanging heat between the circulating water W6 and a heating medium or a cooling medium (e.g., air). The circulating water W6 that has passed through the heat exchanger 22 is returned to the main path 1 through a return path 23 as returned water W7.

[0060] In this step, the control unit 7 controls the flow rate of the circulating water W6 based on the measurement value of the thermometer 5. At least one of a circulation pump 9 and a circulation valve 10 can be used to control the flow rate of the circulating water W6.

[0061] (Second pretreatment process) The clarified water W2 is introduced into the adsorption section 13. In the adsorption section 13, organic matter, inorganic matter (residual chlorine, metals, metal compounds, etc.) contained in the clarified water W2 is adsorbed and removed to obtain adsorption-treated water W3 (water to be treated).

[0062] (Membrane treatment process) The adsorption-treated water W3 is introduced into the membrane treatment section 6. In the membrane treatment section 6, the adsorption-treated water W3 is treated using a separation membrane to obtain membrane-treated water W4.

[0063] (Post-processing process) Hypochlorite is added to the membrane-treated water W4 by the post-treatment unit 8. The membrane-treated water W4 becomes treated water W5 by adding hypochlorite.

[0064] [Effects of the water treatment device and water treatment method according to the second embodiment] In the water treatment device 200 of this embodiment, similar to the water treatment device 100 (see FIG. 1), the treatment performance in the membrane treatment unit 6 can be improved. Therefore, the quality of the treated water W5 can be ensured. In the water treatment device 200, the heat exchanger 22 can fully utilize the heat of the circulating water W6, which is groundwater.

[0065] According to the water treatment method of this embodiment, similar to the water treatment method of the first embodiment, the treatment performance in membrane treatment can be improved. Therefore, the water quality of the treated water W5 can be ensured. In this water treatment method, the heat exchanger 22 can fully utilize the heat of the circulating water W6, which is groundwater.

[0066] Although the present invention has been described above with reference to several specific embodiments, these embodiments are presented as examples and do not limit the scope of the present invention. Each embodiment described in this specification can be modified in various ways within the scope of the effects of the invention, and can be combined with features described in other embodiments within the scope of feasibility.

[0067] For example, in the water treatment device 100 shown in FIG. 1, the circulation path 21 connects the reservoir 4 and the heat exchanger 22, but the circulation path 21 may branch off from the main path 1. 1, the heat exchanger 3 is disposed downstream of the pretreatment unit 2, but the location of the heat exchanger 3 is not particularly limited as long as it is upstream of the membrane treatment unit 6. For example, the heat exchanger 3 may be disposed upstream of the pretreatment unit 2.

[0068] The water treatment device 100 shown in FIG. 1 includes a pre-treatment device 2 and a post-treatment device 8, but the water treatment device of the embodiment can also be configured without one or both of the pre-treatment device 2 and the post-treatment device 8. 1, the circulation path 21 connects the storage section 4 and the heat exchanger 22, and the return path 23 connects the heat exchanger 22 and the main path 1, but the configurations of the circulation path 21 and the return path 23 are not limited to this. For example, the circulation path 21 may connect the main path 1 and the heat exchanger 22, and the return path 23 may connect the heat exchanger 22 and the storage section 4. [Explanation of symbols]

[0069] 1...main path, 2...pretreatment section, 3...heat exchange section, 4...storage section, 5...thermometer, 6...membrane treatment section, 7...control section, 9...circulation pump, 10...circulation valve, 21...circulation path, 22...heat exchanger, 23...return path

Claims

1. A water treatment device for purifying groundwater, a main path through which the groundwater is guided as water to be treated; A heat exchange unit that performs heat exchange of the water to be treated; a membrane treatment unit that performs membrane treatment on the water to be treated that has passed through the heat exchange unit; a thermometer for measuring the temperature of the water to be treated between the heat exchange unit and the membrane treatment unit; a control unit for controlling the flow rate of the water to be treated, The heat exchange unit is a circulation path that guides at least a portion of the water to be treated in the main path as circulating water; a heat exchanger that exchanges heat with the circulating water; a return path that returns the circulating water that has passed through the heat exchanger to the main path, The control unit controls the flow rate of the circulating water based on the measurement value of the thermometer. Water treatment equipment.

2. a circulation pump that sends the circulating water to the heat exchanger is provided in the circulation path; When the measurement value of the thermometer is outside the allowable temperature range of the membrane processing unit, the control unit reduces the output of the circulation pump to reduce the flow rate of the circulating water. The water treatment device according to claim 1.

3. a circulation valve that opens and closes the circulation path is provided in the circulation path, When the measurement value of the thermometer is outside the allowable temperature range of the membrane processing unit, the control unit reduces the flow rate of the circulating water by reducing the opening of the circulation valve. The water treatment device according to claim 1.

4. Further provided is a storage section that stores the water to be treated that is guided to the heat exchange section. The water treatment device according to any one of claims 1 to 3.

5. A pretreatment unit is further provided upstream of the membrane treatment unit to pretreat the water to be treated. The water treatment device according to any one of claims 1 to 3.

6. A water treatment method for purifying groundwater, comprising: a heat exchange step of introducing the groundwater as water to be treated and performing heat exchange on the water to be treated; a membrane treatment step of performing membrane treatment on the water to be treated that has undergone the heat exchange step, In the heat exchange step, at least a portion of the water to be treated is guided as circulating water through a circulation path, and heat exchange of the circulating water is performed using a heat exchanger. Then, the circulating water that has passed through the heat exchanger is returned. measuring the temperature of the water to be treated between the heat exchange step and the membrane treatment step; controlling the flow rate of the circulating water based on the measured temperature; Water treatment methods.

7. a circulation pump that sends the circulating water to the heat exchanger is provided in the circulation path; When controlling the flow rate of the circulating water, if the measured temperature value is outside the allowable temperature range of the membrane treatment, the flow rate of the circulating water is reduced by reducing the output of the circulating pump. The water treatment method according to claim 6.

8. a circulation valve for opening and closing the circulation path is provided in the circulation path; When controlling the flow rate of the circulating water, if the measured temperature value is outside the allowable temperature range of the membrane treatment, the flow rate of the circulating water is reduced by reducing the opening of the circulation valve. The water treatment method according to claim 6.

9. The method further includes a preliminary measurement step of determining an allowable temperature range for the membrane treatment by measuring the relationship between the temperature of the water to be treated and the rejection rate of the membrane treatment prior to the heat exchange step. The water treatment method according to any one of claims 6 to 8.

Images