Water treatment apparatus and water treatment method

Abstract

To provide a water treatment apparatus and a water treatment method capable of efficiently using heat of underground water and suppressing corrosion of a liquid contact part of a heat exchange part.SOLUTION: A water treatment apparatus 20A includes a pumping piping L1 for pumping up underground water in a well 10 as water to be treated W1 and a heat exchange part 1 for heat-exchanging the water to be treated W1 pumped up by the pumping piping L1, wherein a first end part of the pumping piping L1 is connected to a pumping pump 9 and a second end part of the pumping piping L1 is directly connected to the heat exchange part 1.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] Groundwater stored in aquifers 10 meters or less underground remains at a nearly constant temperature whether it is rain that falls in the summer or melting snow that seeps in during the winter. When this water is pumped up as well water, it feels cold in the summer and warm in the winter because the well water is at nearly the same temperature in both summer and winter.

[0003] In Japan, although it varies by region, groundwater temperatures in the Kanto Plain, Nobi Plain, and Osaka Plain are between 15 and 18°C, and the annual temperature difference is generally within 1°C. Of course, in shallow wells that are only a few meters deep, the annual temperature difference can be affected by the outside air. Conversely, in deep wells that are more than 100 meters underground, the groundwater temperature gradually increases the deeper it goes from the surface due to rising ground temperatures. The reason the groundwater temperature increases the deeper it goes from the surface is because it is influenced by magma inside the Earth. Although it varies by region, it rises by about 3°C ​​for every 100 meters.

[0004] Deep well water and shallow well water are generally the most accessible groundwater sources. Deep well water is groundwater pumped from a confined aquifer 10 to 200 meters underground. Shallow well water is groundwater pumped from the top of a confined aquifer 1 to 50 meters underground. The deeper the water, the closer the temperature is to 15 to 18°C. In this article, well water refers to water pumped from either a deep or shallow well.

[0005] The thermal energy of groundwater pumped up from deep or shallow wells can also be utilized. For example, Patent Document 1 proposes a heat utilization system that utilizes the heat of groundwater. The heat utilization system in Patent Document 1 includes a pretreatment means that treats groundwater using a separation membrane, and a heat exchanger that is installed downstream of the pretreatment means and performs heat exchange using the groundwater treated by the pretreatment means. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-113662 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the heat utilization system of Patent Document 1, heat exchange is carried out after the membrane separation device, so the heat of the groundwater pumped up from the deep well is affected by the outside air through the piping, tanks, and devices. As a result, the heat of the groundwater that could have been used for heat exchange is lost, resulting in a decrease in the efficiency of heat recovery.

[0008] In addition, when heat exchange is performed downstream of the membrane separation device as in Patent Document 1, dissolved oxygen is likely to be mixed into the groundwater. When producing purified water for domestic use or drinking water, it is often disinfected with an oxidizing agent such as hypochlorous acid. When water containing such dissolved oxygen or oxidizing substances such as oxidizing agents comes into contact with the liquid-contacting parts (especially copper piping) of the downstream heat exchanger, corrosion reactions in the liquid-contacting parts progress quickly. As a result, water leakage from the heat exchanger or damage to the equipment may occur.

[0009] The present invention provides a water treatment device and a water treatment method that can fully utilize the heat of groundwater and can suppress corrosion of the liquid-contacting parts of the heat exchanger. [Means for solving the problem]

[0010] The present invention has the following aspects. [1] A water treatment device for purifying groundwater, a pumping pipe for pumping the groundwater as water to be treated; a heat exchange unit that performs heat exchange of the water to be treated pumped up by the water pumping pipe; Equipped with A water treatment device, wherein a first end of the water pumping pipe is connected to a water pumping pump, and a second end of the water pumping pipe is directly connected to the heat exchange unit. [2] A storage tank for storing heat-exchanged water generated by heat exchange of the water to be treated in the heat exchange unit; a heat exchange water supply pipe for passing the heat exchange water from the heat exchange unit to the storage tank; The water treatment device according to [1], further comprising: [3] The water treatment device according to [2], further comprising a raw water supply pipe for guiding the heat exchange water from the storage tank to a downstream side of the storage tank. [4] The water treatment device according to [3], wherein a raw water pump for supplying the heat exchange water to a subsequent stage is provided in the raw water supply pipe. [5] The water treatment device according to any one of [2] to [4], further comprising a circulation pipe for returning a portion of the heat exchange water stored in the storage tank to the heat exchange section. [6] The water treatment device according to [5], wherein a circulation pump is provided in the circulation piping for returning a portion of the heat exchange water stored in the storage tank to the heat exchange section. [7] The water treatment device according to any one of [3] to [6], further comprising a branch circulation pipe that returns a portion of the heat exchange water flowing through the raw water supply pipe to the heat exchange section. [8] A water treatment device as described in [7], in which a circulation valve is provided in the branch circulation pipe for changing the return flow rate when returning a portion of the heat exchange water flowing through the raw water supply pipe to the heat exchange section.

[0011] [9] A water treatment method for purifying groundwater, comprising: a pumping step of pumping the groundwater as water to be treated; a heat exchange step of directly supplying the water to be treated to a heat exchange section that performs heat exchange on the water to be treated pumped up in the pumping step; and A water treatment method, wherein a first end of a pumping pipe used in the pumping step is connected to a pumping pump, and a second end of the pumping pipe is directly connected to the heat exchanger.

[10] The water treatment method described in [9], further comprising a circulation process in which a portion of the heat exchange water produced by the heat exchange of the treated water in the heat exchange section is returned to the heat exchange section, and the returned heat exchange water is used to perform heat exchange again in the heat exchange section.

[11] The water treatment method described in

[10] , further comprising a control step of controlling the return flow rate when returning a portion of the heat exchange water to the heat exchange section based on the water temperature of the heat exchange water returned in the circulation step.

[12] A water treatment method using the water treatment device according to any one of [1] to [8]. [Effects of the Invention]

[0012] According to the present invention, a water treatment apparatus and a water treatment method are provided that can fully utilize the heat of groundwater and can suppress corrosion of the liquid-contacting parts of the heat exchanger. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing an example of a water treatment device. [Figure 2] FIG. 2 is a schematic diagram showing another example of the water treatment device. [Figure 3] FIG. 3 is a schematic diagram showing another example of the configuration of a water treatment device. [Figure 4] FIG. 4 is a schematic diagram showing another example of the configuration of a water treatment device. DETAILED DESCRIPTION OF THE INVENTION

[0014] The meanings of the terms are as follows: The symbol "to" indicating a range of values ​​means that the values ​​before and after it are included as the lower and upper limits.

[0015] The target of treatment in the water treatment device and water treatment method is groundwater. The groundwater is pumped up from, for example, a deep well or a shallow well. In a deep well, groundwater from a confined aquifer can be used. The groundwater can be, for example, groundwater from a depth of 1 to 200 m below ground. The temperature of the groundwater pumped up from a deep or shallow well is, for example, 15 to 18°C.

[0016] 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.

[0017] Hereinafter, several embodiments of the present invention will be described with reference to the drawings. However, the following description is for representative examples, and the present invention is not limited to the following description. The dimensional ratios in the drawings are for the convenience of explanation and may differ from the actual ones. In the following drawings, the same components are indicated by the same reference numerals, and descriptions of overlapping components may be omitted.

[0018] [First embodiment] (Water treatment equipment) First, a first embodiment of a water treatment device 20A shown in Fig. 1 will be described. The water treatment device 20A is used to purify groundwater from a well 10. The water treatment device 20A includes a pumping pipe L1, a heat exchanger 1, a heat-exchanged water supply pipe L2, a storage tank 2, a raw water supply pipe L3, a raw water pump 3, an oxidation treatment unit 4, a sand filtration treatment unit 5, an activated carbon treatment unit 6, a membrane treatment unit 7, and a disinfection treatment unit 8.

[0019] The pumping pipe L1 is used to pump up groundwater from a well 10 as water to be treated W1. A first end of the pumping pipe L1 is connected to a pumping pump 9 disposed in the well 10. A second end of the pumping pipe L1 is directly connected to a heat exchanger (not shown) of the heat exchange unit 1. The water pump 9 is not particularly limited as long as it can pump up groundwater, and examples thereof include a submersible pump and a land pump.

[0020] Here, the direct connection of the second end of the water pumping pipe L1 to the heat exchanger 1 means that the pumped water W1 to be treated is connected so that it can pass directly through the heat exchanger 1 without undergoing any water treatment. In such a water treatment device, as illustrated in Fig. 1, no processing units for performing various water treatments such as turbidity removal, chemical treatment, or purification treatment are disposed between the water pumping pipe L1 and the heat exchanger 1.

[0021] In one example, the length of the pumping pipe L1 extending from the pumping pipe L1 exposed above the ground surface of the well 10 to the inlet of the heat exchanger 1 is preferably 100 m or less, more preferably 50 m or less, and even more preferably 30 m or less, from the viewpoint of efficiently utilizing the heat of the groundwater. In another example, the pumping pipe L1 does not have to be exposed above the ground surface of the well 10, in which case the heat exchanger 1 may be located below the ground surface of the well 10 (underground side).

[0022] The heat exchange unit 1 is for performing heat exchange of the water to be treated W1 pumped up through the water pumping pipe L1. The heat exchange unit 1 may be used for heating the heat exchange target, such as for heating purposes, or for cooling the heat exchange target, such as for cooling purposes.

[0023] The heat exchanger (not shown) of the heat exchanger section 1 can be, for example, a groundwater cooler, an outdoor unit of an air conditioner, a heat pump, a fan coil, a chiller (cooling water circulation device), etc. The heat exchanger is preferably a heat exchanger used in an air conditioner. The heat exchanger performs heat exchange using the heat of the water to be treated W1.

[0024] The material of the liquid-contacting part of the heat exchanger 1 that is in contact with the second end of the water pumping pipe L1 is not particularly limited, but may be a metal material such as copper, stainless steel, etc. In particular, since copper pipes are prone to corrosion, the technical significance of applying the water treatment device and water treatment method of this embodiment becomes even greater.

[0025] When the water pump 9 is stopped for a certain period of time, the water to be treated W1 remains in the liquid-contacting portion of the heat exchanger 1, and as the retention time increases, a higher concentration of copper dissolves therein than when the water pump 9 is operating. The copper concentration of the water retained in the heat exchanger is measured in advance for each retention time, and a retention time within a range in which the copper concentration does not exceed 1.0 mg / L is measured. A mechanism may be provided to discharge the water retained in the heat exchanger outside the system if the retention time is exceeded. The copper concentration standard of the heat exchange water W2 is not particularly limited as long as it does not exceed 1.0 mg / L, but is preferably 1.0 mg / L or less, more preferably 0.5 mg / L or less, and even more preferably 0.2 mg / L or less.

[0026] In one example, a heat exchanger (not shown) can utilize the heat of the water to be treated W1 by heat exchange between a heat medium or refrigerant (e.g., air) and the water to be treated W1. After the heat of the water to be treated W1 is utilized, the water to be treated W1 becomes heat-exchanged water W2. The water to be treated W1 is subjected to heat exchange in the heat exchange section 1, thereby generating the heat-exchanged water W2.

[0027] The heat exchange water supply pipe L2 is used to pass the heat exchange water W2 from the heat exchange section 1 to the storage tank 2. A first end of the heat exchange water supply pipe L2 is connected to a heat exchanger (not shown) of the heat exchange section 1, and a second end of the heat exchange water supply pipe L2 is connected to the storage tank 2. The storage tank 2 is used to store the heat exchange water W2.

[0028] If the material of the liquid-contacting part of the heat exchange unit 1 is copper, copper will dissolve in the water to be treated W1. If the water is intended for drinking, it must be operated within a range that does not exceed the copper concentration of 1.0 mg / L, which is the standard value for tap water quality. The copper concentrations of the water to be treated W1 and the heat exchange water W2 should be measured in advance. If there is a possibility that the copper concentration will exceed the standard value for tap water quality, the modified example shown in Figure 4 is useful.

[0029] The water treatment device 1D shown in Fig. 4 includes a bypass pipe L6. A first end of the bypass pipe L6 is connected to a portion of the water pumping pipe L1, and a second end of the bypass pipe L6 is connected to a portion of the heat exchange water supply pipe L2. A valve V1 is provided in the water pumping pipe L1, and a valve V2 is provided in the bypass pipe L6. A drainage pipe L7 is connected to a portion of the heat exchange water supply pipe L2, and a drain valve V3 is provided in the drainage pipe L7.

[0030] Bypass piping L6 allows a portion of the water to be treated W1 to be supplied to the storage tank 2 without passing through the heat exchange section 1. The opening and closing of valves V1 and V2 can be changed so that the copper concentration of the heat exchange water W2 is maintained within a range not exceeding 1.0 mg / L.

[0031] Referring again to Figure 1, the raw water supply pipe L3 is used to guide the heat exchange water W2 from the storage tank 2 to a stage downstream of the storage tank 2. The storage tank 2 is connected to a first end of the raw water supply pipe L3. The raw water supply pipe L3 is provided with a raw water pump 3, an oxidation treatment unit 4, a sand filtration treatment unit 5, an activated carbon treatment unit 6, a membrane treatment unit 7, and a disinfection treatment unit 8, in this order. The raw water pump 3 is used to supply the heat exchange water W2 to the oxidation treatment unit 4, sand filtration treatment unit 5, activated carbon treatment unit 6, membrane treatment unit 7, and disinfection treatment unit 8, which are located downstream.

[0032] The oxidation treatment unit 4 oxidizes the heat exchange water W2 using an oxidizing agent. Examples of the oxidizing agent include, but are not limited to, hypochlorites such as sodium hypochlorite. The heat exchange water W2 becomes oxidized water W3 by adding the oxidizing agent.

[0033] The oxidation treatment unit 4 can oxidize impurities such as iron and manganese in the groundwater. In the water treatment device 20A, the oxidation treatment unit 4 is installed after the heat exchange unit 1 to prevent corrosion of the liquid-contacting parts of the heat exchange unit 1.

[0034] The sand filtration unit 5 is an example of a turbidity removal unit. The sand filtration unit 5 is a sand filtration device filled with sand as a filter medium. The sand filtration unit 5 removes turbid components (e.g., solids) from the oxidation treated water W3. After passing through the sand filtration unit 5, the oxidation treated water W3 becomes sand filtered water W4.

[0035] The activated carbon treatment unit 6 is also an example of a clarification treatment unit. The activated carbon treatment unit 6 is an adsorption device filled with activated carbon as a filter medium. The activated carbon treatment unit 6 removes organic and inorganic substances (residual chlorine, metals, metal compounds, etc.) from the sand filtration treated water W4 by adsorption. After passing through the activated carbon treatment unit 6, the sand filtration treated water W4 becomes activated carbon treated water W5.

[0036] The membrane processing unit 7 performs membrane treatment on the activated carbon treated water W5. The membrane processing unit 7 treats the activated carbon treated water W5 using a separation membrane to obtain membrane treated water W6. The membrane treated water W6 is permeate that has passed through 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 filtration 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.

[0037] The disinfection treatment unit 8 disinfects the membrane-treated water W6 using a disinfectant. Examples of disinfectants include, but are not limited to, hypochlorites such as sodium hypochlorite. The membrane-treated water W6 becomes treated water W7 by adding the disinfectant.

[0038] (Water treatment method) Next, an example of a water treatment method using the above-described water treatment device 20A will be described. First, groundwater is pumped up from the well 10 as the water to be treated W1 (pumping step). Next, the water to be treated W1 pumped up in the pumping step is directly supplied to the heat exchanger 1 (heat exchanging step).

[0039] Here, directly supplying the water to be treated W1 pumped up in the pumping process to the heat exchanger 1 means that the pumped water to be treated W1 is not subjected to any water treatment and is passed directly through the heat exchanger 1. In this water treatment method, as illustrated in Fig. 1, no processing units for performing various water treatments such as turbidity removal, chemical treatment, or purification are disposed between the pumping pipe L1 and the heat exchanger 1.

[0040] A first end of the pumping pipe L1 is connected to the pumping pump 9 of the well 10, and a second end of the pumping pipe L1 is directly connected to the heat exchanger 1. This makes it possible to minimize heat loss from the groundwater W1 (water to be treated W1) until it is supplied to the heat exchanger 1.

[0041] The temperature difference between the groundwater temperature in the well 10 and the water to be treated W1 at the inlet of the heat exchanger 1 is not particularly limited, but may be 2.0° C. or less, 1.0° C. or less, or 0.5° C. or less. To reduce this temperature difference, the outer periphery of the pumping pipe L1 may be wrapped in a heat-insulating material.

[0042] The dissolved oxygen concentration of the water to be treated W1 at the inlet of the heat exchange section 1 is preferably 2.0 mg / L or less, more preferably 1.0 mg / L or less, and even more preferably 0.5 mg / L or less. The dissolved oxygen concentration of groundwater is often nearly 0 mg / L. Therefore, the lower the dissolved oxygen concentration of the water to be treated W1 at the inlet of the heat exchange section 1, the better.

[0043] The heat exchange water W2 produced in the heat exchange section 1 is temporarily stored in a storage tank 2 and then flows through a raw water supply pipe L3. By the action of a raw water pump 3, the heat exchange water W2 is sequentially supplied to an oxidation treatment section 4, a sand filtration treatment section 5, an activated carbon treatment section 6, a membrane treatment section 7, and a disinfection treatment section 8. During this time, the heat exchange water W2 sequentially becomes oxidation-treated water W3, sand filtration-treated water W4, activated carbon-treated water W5, membrane-treated water W6, and treated water W7.

[0044] The use of the treated water W7 is not particularly limited, but it can be used, for example, as drinking water or purified water. According to the water treatment device 20A, heat exchange can be performed in conjunction with the production of purified water or drinking water. Therefore, heat exchange is stopped when the water supply is stopped, such as at night. Such a water treatment device 20A is suitable for use in places such as shopping malls where water supply and heating / cooling are used simultaneously.

[0045] According to the water treatment device 20A, groundwater from a well 10 can be treated in one pass, without branching or joining pipes, to produce drinking water or purified water, passing through the heat exchanger 1, oxidation treatment unit 4, sand filtration treatment unit 5, activated carbon treatment unit 6, membrane treatment unit 7, and disinfection treatment unit 8 in that order. This allows for a simple structure that allows for both the production of drinking water or purified water and the utilization of groundwater heat.

[0046] The temperatures of the heat exchange water W2 and the treated water W7 are preferably monitored using a water thermometer or the like. Water temperature monitoring may be performed remotely or on-site. For example, when the heat exchange unit 1 is used for heating purposes, an alarm may be issued when the temperature of the heat exchange water W2 falls below the lower limit of a preset allowable temperature range. When the heat exchange unit 1 is used for cooling purposes, an alarm may be issued when the temperature of the heat exchange water W2 rises above the upper limit of a preset allowable temperature range. When an alarm is issued, the heat exchange can be stopped by stopping the water pump 9.

[0047] The "allowable temperature range" is the temperature range in which the separation membrane in the membrane processing section 7 can be used, that is, the temperature range of the membrane feed water in which the performance (for example, rejection) of the separation membrane can be maintained. The allowable temperature range of the membrane treatment section 7 can be determined by measuring the relationship between the temperature of the membrane feed water to be treated and the rejection rate of membrane treatment in the membrane treatment section 7. For example, the allowable temperature range of the membrane treatment section (operating temperature range of the separation membrane) can be determined from the following viewpoints.

[0048] i) The correlation between the temperature of the membrane feed water and the rejection rate specified by the separation membrane manufacturer; ii) The temperature of the membrane supply water corresponding to the rejection rate obtained according to the water quality of the treated water required when applied to the water treatment device; iii) Temperatures set taking into account practical issues when providing treated water.

[0049] Regarding i) and ii) above, when the water temperature is within the temperature range allowed by the membrane treatment unit 7, 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 treated through the membrane appropriately. On the other hand, when the temperature of the water to be treated falls below the temperature allowed by the membrane treatment unit 7, 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 7, the pore size of the separation membrane becomes larger, and the performance of removing impurities decreases.

[0050] Regarding the above-mentioned iii), considering the quality of the treated water, it is preferable to set the upper limit of the tap water temperature so that the treated water meets the 51 standard values ​​for tap water. Also, it is preferable to set the lower limit of the allowable temperature range for the membrane treatment section to 5°C to prevent freezing problems.

[0051] (Mechanism of action) According to the first embodiment described above, the second end of the water pumping pipe L1 is directly connected to the heat exchange unit 1. This makes it possible to prevent heat loss from the groundwater (the water to be treated W1) to the maximum extent possible before it is supplied to the heat exchange unit 1. In addition, it is easy to prevent oxygen from being mixed into the water to be treated W1 from the atmosphere before it is supplied to the heat exchange unit 1. Therefore, the dissolved oxygen concentration of the water to be treated W1 supplied to the heat exchanger of the heat exchange unit 1 is also easy to reduce, thereby suppressing corrosion of the liquid-contacting parts of the heat exchange unit.

[0052] [Second embodiment] The water treatment device 20B shown in FIG. 2 differs from the water treatment device 20A shown in FIG. 1 in the following two points. The water treatment device 20B further includes a circulation pipe L4 for returning a portion of the heat exchange water W2 stored in the storage tank 2 to the heat exchange unit 1. A circulation pump 11 for returning a portion of the heat exchange water W2 stored in the storage tank 2 to the heat exchange section 1 is provided in the circulation pipe L4. Valve V4 is installed on circulation pipe L4.

[0053] The water treatment device 20B also operates under the same mechanism as the water treatment device 20A in Fig. 1. In addition to this, the water treatment device 20B has the following features.

[0054] A first end of the circulation pipe L4 is immersed in the heat exchange water W2 in the storage tank 2, and a second end of the circulation pipe L4 is connected to a heat exchanger (not shown) of the heat exchange section 1. According to the water treatment device 20B, heat exchange can be performed while circulating a portion of the heat exchange water W2 stored in the storage tank 2 between the storage tank 2 and the heat exchange section 1. More specifically, a portion of the heat exchange water W2 can be returned to the heat exchange section 1, and the returned heat exchange water W2 can be used to perform heat exchange again in the heat exchanger (not shown) of the heat exchange section 1 (circulation process). Using the storage tank 2 as a cushion tank in this way is also useful for effectively utilizing the heat of groundwater and the water to be treated W1.

[0055] According to water treatment device 20B, heat exchange can be performed by operating circulation pump 11 between storage tank 2 and heat exchanger 1. Therefore, even if raw water pump 3 is stopped during periods of water outage, such as overnight, heat exchange can be performed at any time by operating circulation pump 11, regardless of the operation of producing drinking water or purified water. Therefore, water treatment device 20B can be suitably applied to hospitals, welfare centers, apartment buildings, detached houses, etc.

[0056] In the water treatment device 20B, it is also preferable to monitor the water temperature of the heat exchange water W2 and the treated water W7 using a water thermometer or the like, but it is also useful to control the return flow rate when returning a portion of the heat exchange water W2 to the heat exchange section 1 based on the water temperature of the returned heat exchange water W2' (control process).

[0057] The return flow rate of the heat exchange water W2' can be changed by the output of the circulation pump 11. In a preferred example, the circulation pump 11 can be used to control the return flow rate when returning a portion of the heat exchange water W2 to the heat exchange section 1 based on the temperature of the heat exchange water W2' flowing through the circulation pipe L4.

[0058] For example, when the temperature of the heat exchange water W2' is within the temperature range allowed by the membrane treatment unit 7 (e.g., 5°C or higher and less than 25°C), a portion of the heat exchange water W2 in the storage tank 2 can be returned to the heat exchange unit 1 to perform heat exchange. On the other hand, when the temperature of the heat exchange water W2' is outside the temperature range allowed by the membrane treatment unit 7 (e.g., less than 5°C or more than 25°C), the heat exchange water W2' is not circulated using the storage tank 2 and the heat exchange unit 1. In addition, when the temperature of the heat exchange water W2' matches the outside air temperature, the heat exchange water W2' is not circulated using the storage tank 2 and the heat exchange unit 1.

[0059] For example, when the heat exchange unit 1 is used for heating purposes, it is useful to increase the return flow rate of the heat exchange water W2 from the storage tank 2 by changing the output of the circulation pump 11 so as to increase the flow rate of the heat exchange water W2' when the temperature of the heat exchange water W2' falls below the lower limit of a preset allowable temperature range.When the heat exchange unit 1 is used for cooling purposes, it is useful to decrease the return flow rate of the heat exchange water W2 from the storage tank 2 by changing the output of the circulation pump 11 so as to decrease the flow rate of the heat exchange water W2' when the temperature of the heat exchange water W2 rises above the upper limit of a preset allowable temperature range.

[0060] In the water treatment device 20B, it is preferable to monitor the dissolved oxygen concentration of the heat exchange water W2′ flowing through the circulation pipe L4 in order to control the corrosion state of the liquid-contacting portion between the second end of the circulation pipe L4 and the heat exchanger (not shown) of the heat exchange unit 1.

[0061] [Third embodiment] The water treatment device 20C shown in FIG. 3 differs from the water treatment device 20A shown in FIG. 1 in the following two points. The water treatment device 20C further includes a branch circulation pipe L5 that returns a portion of the heat exchange water W2 flowing through the raw water supply pipe L3 to the heat exchange unit 1. A circulation valve V5 for changing the return flow rate when returning a portion of the heat exchange water W2 flowing through the raw water supply pipe L3 to the heat exchange section 1 is provided in the branch circulation pipe L5.

[0062] The water treatment device 20C also operates under the same mechanism as the water treatment device 20A in Fig. 1. In addition to this, the water treatment device 20C has the following features.

[0063] A first end of the branch circulation pipe L5 is connected to the middle of the raw water supply pipe L3, and a second end of the branch circulation pipe L5 is connected to the heat exchanger (not shown) of the heat exchanger unit 1. According to the water treatment device 20C, heat exchange can be performed by circulating a portion of the heat exchange water W2 flowing through the raw water supply pipe L3 through the heat exchanger unit 1, the storage tank 2, and the raw water supply pipe L3 in that order. More specifically, a portion of the heat exchange water W2 can be returned to the heat exchanger unit 1, and the returned heat exchange water W2 can be used to perform heat exchange again in the heat exchanger (not shown) of the heat exchanger unit 1 (circulation process). Using the storage tank 2 as a cushion tank in this way is also useful for effectively utilizing the heat of groundwater and the water to be treated W1.

[0064] A first end of the branch circulation pipe L5 is connected to the raw water supply pipe L3 downstream of the raw water pump 3. According to the water treatment device 20C, the raw water pump 3 operates to supply the heat exchange water W2 sequentially to the oxidation treatment section 4, sand filtration treatment section 5, activated carbon treatment section 6, membrane treatment section 7, and disinfection treatment section 8, while also returning a portion of the heat exchange water W2 to the heat exchange section 1. Therefore, the raw water pump 3 can be shared between the production of drinking water and purified water and heat exchange in the water treatment device 20C. As a result, the number of pumps required can be reduced.

[0065] In the water treatment device 20C, it is also preferable to monitor the water temperature of the heat exchange water W2 and the treated water W7 using a water thermometer or the like, but it is also useful to control the return flow rate when returning a portion of the heat exchange water W2 to the heat exchange section 1 based on the water temperature of the returned heat exchange water W2' (control process).

[0066] In the water treatment device 20C, the flow rate of the returned heat exchange water W2' can be changed by changing the opening degree of the valve V5. In a preferred example, the return flow rate when returning a portion of the heat exchange water W2 to the heat exchange unit 1 can be controlled using the valve V5 based on the temperature of the heat exchange water W2' flowing through the branch circulation pipe L5.

[0067] For example, when the temperature of the heat exchange water W2' is within the temperature range allowed by the membrane treatment unit 7 (e.g., 5°C or higher and lower than 25°C), a portion of the heat exchange water W2 flowing through the raw water supply pipe L3 can be returned to the heat exchange unit 1 to perform heat exchange. On the other hand, when the temperature of the heat exchange water W2' is outside the temperature range allowed by the membrane treatment unit 7 (e.g., lower than 5°C or higher than 25°C), the heat exchange water W2' is not circulated using the raw water supply pipe L3, the heat exchange unit 1, and the storage tank 2. In addition, when the temperature of the heat exchange water W2' matches the outside air temperature, the heat exchange water W2' is not circulated using the raw water supply pipe L3, the heat exchange unit 1, and the storage tank 2.

[0068] For example, when the heat exchange unit 1 is used for heating purposes, it is useful to increase the return flow rate of the heat exchange water W2 from the raw water supply pipe L3 by changing the opening of the valve V5 so that the flow rate of the heat exchange water W2' increases when the temperature of the heat exchange water W2' falls below the lower limit of a preset allowable temperature range. When the heat exchange unit 1 is used for cooling purposes, it is useful to decrease the return flow rate of the heat exchange water W2 from the raw water supply pipe L3 by changing the opening of the valve V5 so that the flow rate of the heat exchange water W2' decreases when the temperature of the heat exchange water W2 rises above the upper limit of a preset allowable temperature range.

[0069] In the water treatment device 20C, it is preferable to monitor the dissolved oxygen concentration of the heat exchange water W2′ flowing through the branch circulation pipe L5 in order to control the corrosion state of the liquid-contacting portion between the second end of the branch circulation pipe L5 and the heat exchanger (not shown) of the heat exchange unit 1.

[0070] [Other embodiment examples] Although one embodiment has been described above by showing one example embodiment, the present invention is not limited to the example embodiment disclosed in this specification and can be appropriately modified and implemented without departing from the spirit of the invention. The embodiment disclosed in this specification can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. [Industrial Applicability]

[0071] According to the present invention, a water treatment apparatus and a water treatment method are provided that can fully utilize the heat of groundwater and can suppress corrosion of the liquid-contacting parts of the heat exchanger. [Explanation of symbols]

[0072] 1 Heat exchange section 2. Reservoir 3 Raw water pump 4. Oxidation treatment section 5 Sand filtration processing section 6 Activated carbon treatment section 7. Membrane processing section 8. Disinfection Processing Unit 9. Water pump 10. Well 11 Circulation pump L1 Pumping pipe L2 Heat exchange water supply piping L3 raw water supply pipe L4 Circulation piping L5 Branch circulation piping

Claims

1. A water treatment device for purifying groundwater, a pumping pipe for pumping the groundwater as water to be treated; a heat exchange unit that performs heat exchange of the water to be treated pumped up by the water pumping pipe; Equipped with A water treatment device, wherein a first end of the water lifting pipe is connected to a water lifting pump, and a second end of the water lifting pipe is directly connected to the heat exchange unit.

2. a storage tank for storing heat-exchanged water generated by heat exchange of the water to be treated in the heat exchange unit; a heat exchange water supply pipe for passing the heat exchange water from the heat exchange unit to the storage tank; The water treatment device of claim 1 further comprising:

3. The water treatment device according to claim 2 , further comprising a raw water supply pipe for guiding the heat exchange water from the storage tank to a stage downstream of the storage tank.

4. The water treatment device according to claim 3 , further comprising a raw water pump provided in the raw water supply pipe for supplying the heat exchange water to a downstream stage.

5. The water treatment device according to claim 2 , further comprising a circulation pipe that returns a portion of the heat exchange water stored in the storage tank to the heat exchange section.

6. The water treatment device according to claim 5, further comprising a circulation pump provided in the circulation pipe for returning a portion of the heat exchange water stored in the storage tank to the heat exchange section.

7. The water treatment device according to claim 3 , further comprising a branch circulation pipe that returns a portion of the heat exchange water flowing through the raw water supply pipe to the heat exchange section.

8. The water treatment device according to claim 7 , further comprising a circulation valve provided in the branch circulation pipe for changing a return flow rate when a portion of the heat exchange water flowing through the raw water supply pipe is returned to the heat exchange section.

9. A water treatment method for purifying groundwater, comprising: a pumping step of pumping the groundwater as water to be treated; a heat exchange step of directly supplying the water to be treated to a heat exchange section that performs heat exchange on the water to be treated pumped up in the pumping step; and A water treatment method, wherein a first end of a pumping pipe used in the pumping step is connected to a pumping pump, and a second end of the pumping pipe is directly connected to the heat exchanger.

10. The water treatment method according to claim 9, further comprising a circulation process in which a portion of the heat exchange water produced by the heat exchange of the treated water in the heat exchange section is returned to the heat exchange section, and the returned heat exchange water is used to perform heat exchange again in the heat exchange section.

11. The water treatment method according to claim 10, further comprising a control step of controlling the return flow rate when returning a portion of the heat exchange water to the heat exchange section based on the water temperature of the heat exchange water returned in the circulation step.

12. A water treatment method using the water treatment device according to any one of claims 1 to 8.

Images