JP7663195B2 - Water purification device and water purification method - Google Patents

Description

This disclosure relates to a water purification device and a water purification method.

When nutrients such as nitrogen and phosphorus contained in domestic and industrial wastewater flow into oceans, rivers, reservoirs, lakes, and other bodies of water, a large amount of phytoplankton is produced, and a large amount of oxygen is consumed to decompose the dead bodies that accumulate at the bottom of the body of water, resulting in an oxygen-deficient state. In this state, anaerobic bacteria that can decompose in the absence of oxygen become dominant, and the toxic hydrogen sulfide or sulfides produced during decomposition kill the organisms in the body of water.

On the other hand, the surface layer is oxygen-rich due to photosynthesis, and if vertical mixing is performed properly, oxygen deficiency in the bottom layer will not occur. However, in actual water bodies, layers (density stratification) are formed due to differences in density caused by temperature differences between the surface and bottom layers, making it difficult for vertical mixing to occur.

For this reason, a water purification device has been proposed that uses a pump mechanism to forcibly cause vertical mixing in a water body (see, for example, Patent Document 1).

Patent No. 4076824

In conventional water purification devices such as that described in Patent Document 1, a pump mechanism sends the surface water and bottom water through a pipe to a water outlet located in the middle layer, where they are mixed and discharged. This means that the oxygen concentration in the water discharged from the water outlet is low, and the amount of oxygen that can be supplied to the bottom layer is insufficient.

The objective of this disclosure is to provide a water purification device and a water purification method that can efficiently supply oxygen to the bottom layer of a water body.

A water purification device according to some embodiments includes a pipe having an upper opening located in the surface layer of a water body and a lower opening located in the bottom layer of the water body, and a pump mechanism provided in the pipe for pumping water so that one of the upper opening and the lower opening serves as a water intake and the other serves as a water discharge. With this configuration, the water from the surface layer can be taken into the pipe from the upper opening and discharged from the lower opening in the bottom layer, thereby directly supplying the water from the surface layer to the bottom layer, or the water from the bottom layer can be taken into the pipe from the lower opening and discharged from the upper opening in the surface layer, thereby gradually supplying the water from the surface layer to the bottom layer by convection, thereby efficiently supplying oxygen to the bottom layer.

In one embodiment, the water purification device has an internal temperature sensor that measures the temperature of the water inside the pipe at a predetermined depth, an external temperature sensor that measures the temperature of the water outside the pipe at the predetermined depth, and a control unit that controls the flow rate of the pump mechanism so that the difference between the measurement value by the internal temperature sensor and the measurement value by the external temperature sensor falls within a predetermined range. With this configuration, the flow rate of the pump mechanism is limited, i.e., the water is sent slowly (for example, at a flow rate that flows through the pipe at a speed of 1 to 10 mm/s, 1 to 30 mm/s, or 1 to 100 mm/s) so that the difference between the measurement value by the internal temperature sensor and the measurement value by the external temperature sensor falls within a predetermined range (for example, within ±5°C, within ±4°C, or within ±3°C), so that the water can be sent while firmly reducing the temperature difference of the water between the inside and outside of the pipe, and therefore the density difference, due to heat transfer between the inside and outside of the pipe through the pipe. Therefore, the buoyancy or sinking force acting on the sent water caused by the density difference, which becomes the load, i.e. the resistance force, when sending water can be firmly reduced, so that the pump mechanism can be operated efficiently with a low load.

In one embodiment, the internal temperature sensor and the external temperature sensor measure the temperature of the water at the water outlet. With this configuration, the load on the pump mechanism can be reduced simply and efficiently. In addition, the re-surfacing or re-sinking of the discharged water can be more reliably reduced, allowing the discharged water to remain.

In one embodiment, the pump mechanism has a throttling section that reduces the cross-sectional area of the flow passage in the pipe, an impeller disposed in the throttling section, and an electric motor that rotates the impeller. With this configuration, by providing the throttling section, even if the cross-sectional area of the flow passage in the pipe is too large, an impeller of a suitable size that is not too large can be used, and the electric motor can be operated at a suitable rotation range that is not too low and has good energy efficiency. Therefore, the energy efficiency of the pump mechanism can be improved.

In one embodiment, the control unit controls the flow rate of the pump mechanism to a larger flow rate set without using the internal temperature sensor and the external temperature sensor, and then reduces the flow rate of the pump mechanism so that the difference between the measurement value by the internal temperature sensor and the measurement value by the external temperature sensor falls within the predetermined range. With this configuration, the flow rate of the pump mechanism can be controlled quickly and efficiently.

In some embodiments, the water purification method includes an arrangement step of arranging a pipe having an upper opening and a lower opening and a pump mechanism inside so that the upper opening is located in the surface layer of a water area and the lower opening is located in the bottom layer of the water area, and a water supply step of supplying water by the pump mechanism so that one of the upper opening and the lower opening is a water intake port and the other of the upper opening and the lower opening is a water discharge port. With this configuration, the water from the surface layer can be directly supplied to the bottom layer by taking in the water from the upper opening into the pipe and discharging it from the lower opening in the bottom layer, or the water from the bottom layer can be taken in the pipe from the lower opening and discharging it from the upper opening in the surface layer, so that the water from the surface layer can be gradually supplied to the bottom layer by convection, thereby efficiently supplying oxygen to the bottom layer.

In one embodiment, the water conveying step includes an internal temperature measuring step of measuring the temperature of the water inside the pipe at a predetermined depth, an external temperature measuring step of measuring the temperature of the water outside the pipe at the predetermined depth, and a control step of controlling the flow rate of the pump mechanism so that the difference between the measurement value obtained by the internal temperature measuring step and the measurement value obtained by the external temperature measuring step falls within a predetermined range. According to this configuration, the flow rate of the pump mechanism is limited, i.e., the water is conveyed slowly (for example, at a flow rate flowing through the pipe at a speed of 1 to 10 mm/s, 1 to 30 mm/s, or 1 to 100 mm/s) so that the difference between the measurement value obtained by the internal temperature measuring step and the measurement value obtained by the external temperature measuring step falls within a predetermined range (for example, within ±5°C, ±4°C, or ±3°C), thereby making it possible to convey water while firmly reducing the temperature difference, and therefore the density difference, between the water inside and outside the pipe due to heat transfer between the inside and outside of the pipe through the pipe. Therefore, the buoyancy or sinking force acting on the water being pumped due to density differences, which acts as a load or resistance when pumping water, can be effectively reduced, allowing the pump mechanism to operate efficiently with low load. Note that the timing of performing the internal temperature measurement step and the external temperature measurement step does not matter, and they can be performed either first or simultaneously.

In one embodiment, the internal temperature measurement step and the external temperature measurement step measure the temperature of the water at the water outlet. With this configuration, the load on the pump mechanism can be reduced simply and efficiently. In addition, the re-surfacing or re-sinking of the discharged water can be more reliably reduced, allowing the discharged water to remain.

In one embodiment, in the control step, the flow rate of the pump mechanism is controlled to a larger flow rate that is set independently of the internal temperature measurement step and the external temperature measurement step, and then the flow rate of the pump mechanism is reduced so that the difference between the measurement value in the internal temperature measurement step and the measurement value in the external temperature measurement step falls within the predetermined range. With this configuration, the flow rate of the pump mechanism can be controlled quickly and efficiently.

The present disclosure provides a water purification device and a water purification method that can efficiently supply oxygen to the bottom layer of a water body.

FIG. 1 is a layout diagram of a water purification device according to a first embodiment. FIG. 2 is a block diagram of the water purification device shown in FIG. 1 . FIG. 7 is a layout diagram of a water purification device according to a second embodiment.

The following provides a detailed explanation of the embodiments of the present disclosure with reference to the drawings.

The water purification device 1 according to the first embodiment shown in FIG. 1 has a pipe 2, a pump mechanism 3, an internal temperature sensor 4, an external temperature sensor 5, a control unit 6, a power source 7, a float 8, and an anchor 9, and is placed in a body of water 10 such as the ocean, a river, a reservoir, or a lake.

In the water area 10, the difference in density between the surface layer 10a and the bottom layer 10b due to the temperature difference causes layers to form, making vertical mixing difficult, and therefore the bottom layer 10b is prone to becoming hypoxic, which may lead to contamination. The water purification device 1 is a device that uses a pump mechanism 3 to forcibly cause vertical mixing in the water area 10, supplying oxygen from the surface layer 10a to the bottom layer 10b, thereby purifying the water. The surface layer 10a is the layer of water that forms the water surface 10c of the water area 10, and the bottom layer 10b is the layer of water that contacts the bottom surface 10d of the water area 10.

The pipe 2 is cylindrical and extends vertically in the water area 10. The pipe 2 has an upper opening 2a disposed in the surface layer 10a and a lower opening 2b disposed in the bottom layer 10b, and a flow path is formed inside the pipe 2 to connect the upper opening 2a and the lower opening 2b. The upper opening 2a is composed of a plurality of openings that penetrate the pipe 2 in the radial direction. The upper opening 2a may be composed of a single opening. The lower opening 2b is composed of an opening formed at the lower end edge of the pipe 2. The pipe 2 is formed of a plastic film having a thickness of, for example, several mm. Therefore, the pipe 2 has good thermal conductivity and is low-cost. The pipe 2 is flexible and easy to handle until installation. The pipe 2 may be formed of a material other than the plastic film. However, it is preferable that the pipe 2 is formed of a material having thermal conductivity. It is also preferable that the pipe 2 is formed of a flexible material.

The lower end 2c of the pipe 2 is connected and held by the anchor 9 to the bottom surface 10d. The anchor 9 is composed of multiple linear members 9a, and the lower end of each linear member 9a is provided with a locking portion that is inserted into and locked into the bottom surface 10d. The anchor 9 may have any configuration as long as it can connect and hold the lower end 2c of the pipe 2 to the bottom surface 10d.

The upper end 2d of the pipe 2 is connected to the float 8 and is stretched vertically by the buoyancy of the float 8, so that the upper opening 2a is located within the surface layer 10a. There are no particular limitations on the configuration of the float 8, as long as it generates buoyancy in water. Note that, without using the float 8, the upper opening 2a may be located within the surface layer 10a, for example, by mechanically connecting the pipe 2 to another structure.

In addition, a weight may be attached to the lower end 2c of the pipe 2 instead of the anchor 9, so that the pipe 2 can be stretched vertically.

The upper end surface 2e of the pipe 2 protrudes above the water surface 10c, and the power source 7 and the control unit 6 are disposed on the upper end surface 2e. The power source 7 and the control unit 6 may also be disposed underwater. In this embodiment, the pump mechanism 3 is driven by low power, so the power source 7 can be composed of, for example, a natural energy power generation device such as a solar cell and a secondary battery that stores the electricity generated by the device.

The pump mechanism 3 is provided in the pipe 2 and is configured to send water so that the upper opening 2a serves as the water intake 2f and the lower opening 2b serves as the water discharge port 2g. The pump mechanism 3 is also configured with a throttle section 3a that reduces the cross-sectional area of the flow path in the pipe 2, an impeller 3b placed in the throttle section 3a, and an electric motor 3c that rotates the impeller 3b. The electric motor 3c is connected to the power source 7 and the control section 6 via wiring 11. The pump mechanism 3 can send water from the water intake 2f to the water discharge port 2g by rotating the impeller 3b in the throttle section 3a. The throttle section 3a narrows the flow path in a stepped manner, but may be configured to narrow the flow path in a tapered manner.

The pump mechanism 3 is disposed at the top of the pipe 2, but it may be disposed at the bottom of the pipe 2 or at the middle in the vertical direction. However, disposing it at the top of the pipe 2 is preferable because it requires a shorter wiring 11.

The internal temperature sensor 4 is disposed inside the pipe 2 at the water outlet 2g and is configured to measure the temperature of the water inside the pipe 2 at the water outlet 2g. The external temperature sensor 5 is disposed outside the pipe 2 at the water outlet 2g and is configured to measure the temperature of the water outside the pipe 2 at the water outlet 2g.

The control unit 6 is configured to control the flow rate of the pump mechanism 3 so that the difference between the measurement value from the internal temperature sensor 4 and the measurement value from the external temperature sensor 5 falls within a predetermined range (e.g., within ±5°C, within ±4°C, or within ±3°C).

As shown in FIG. 2, the control unit 6 is composed of a computer 6a and a driver 6b. The computer 6a is capable of communicating with the internal temperature sensor 4, the external temperature sensor 5, and the driver 6b, and is configured to calculate the difference between the measurement value obtained by the internal temperature sensor 4 and the measurement value obtained by the external temperature sensor 5, and to instruct the driver 6b on the target rotation speed of the electric motor 3c based on this difference. The driver 6b is electrically connected to the power source 7 and the electric motor 3c, and is configured to control the voltage or current supplied from the power source 7 to the electric motor 3c so that the rotation speed of the electric motor 3c becomes the target rotation speed.

The water purification method using such a water purification device 1 has a placement step and a water supply step. The water supply step has an internal temperature measurement step, an external temperature measurement step, and a control step.

The placement step is a step of placing the pipe 2 so that the upper opening 2a is located in the surface layer 10a and the lower opening 2b is located in the bottom layer 10b. The water supply step is a step of supplying water by the pump mechanism 3 so that the upper opening 2a becomes the water intake 2f and the lower opening 2b becomes the water discharge 2g.

According to this water supply step, the water from the surface layer 10a is taken into the pipe 2 from the upper opening 2a and discharged from the lower opening 2b in the bottom layer 10b, so that the oxygen-rich water from the surface layer 10a can be directly supplied to the bottom layer 10b, and oxygen can be efficiently supplied to the bottom layer 10b.

The internal temperature measurement step is a step in which the temperature of the water inside the pipe 2 at the water outlet 2g is measured by the internal temperature sensor 4. The external temperature measurement step is a step in which the temperature of the water outside the pipe 2 at the water outlet 2g is measured by the external temperature sensor 5. The control step is a step in which the control unit 6 controls the flow rate of the pump mechanism 3 so that the difference between the measurement value in the internal temperature measurement step and the measurement value in the external temperature measurement step falls within the predetermined range. Note that the timing of performing the internal temperature measurement step and the external temperature measurement step does not matter, and they may be performed either first or simultaneously.

According to such a control step, the flow rate of the pump mechanism 3 is limited so that the difference between the measured value in the internal temperature measurement step and the measured value in the external temperature measurement step falls within the predetermined range, i.e., the water is sent slowly (for example, at a flow rate flowing through the pipe 2 at a speed of 1 to 10 mm/s, 1 to 30 mm/s, or 1 to 100 mm/s), and the temperature difference, and therefore the density difference, between the inside and outside of the pipe 2 can be reduced by heat transfer from the inside of the pipe 2 to the outside of the pipe 2 through the pipe 2. Therefore, the buoyancy acting on the water being sent due to the density difference, which becomes the load, or resistance, when sending water, can be reduced, so the pump mechanism 3 can be operated efficiently with low load and low power. In addition, since there is almost no pressure difference between the inside and outside of the pipe 2 by flowing water slowly, the pipe 2 can be made of a flexible material. In addition, if the temperature difference (density difference) between the water coming out of the water outlet 2g and the water around the water outlet 2g is small, the water coming out of the water outlet 2g is less likely to rise again and is more likely to remain in the bottom layer 10b.

In addition, in this embodiment, the pump mechanism 3 is provided with a throttle section 3a, so that even if the flow passage cross-sectional area in the pipe 2 is too large, an impeller 3b of an appropriate size that is not too large can be used, and the electric motor 3c can be operated at an appropriate rotation range that is not too low and has good energy efficiency. Therefore, the energy efficiency of the pump mechanism 3 can be improved.

In the control step, the control unit 6 may control the flow rate of the pump mechanism 3 (i.e., the number of revolutions of the electric motor 3c) to a larger flow rate set based on the temperature distribution of the water area 10, the diameter dimension of the pipe 2, and the axial length of the pipe 2, which have been previously investigated, without relying on the internal temperature measurement step and the external temperature measurement step, and then reduce the flow rate of the pump mechanism 3 so that the difference between the measured value in the internal temperature measurement step and the measured value in the external temperature measurement step falls within the predetermined range. With this configuration, the previously set "larger flow rate" can quickly and reliably form a water flow from the water intake to the water discharge, and then the flow rate can be adjusted, so that the flow rate of the pump mechanism 3 can be quickly and efficiently controlled.

In the water purification device 1 according to the first embodiment, the pump mechanism 3 is configured to send water so that the upper opening 2a serves as the water intake 2f and the lower opening 2b serves as the water discharge 2g. However, as in the second embodiment shown in FIG. 3, the pump mechanism 3 may be configured to send water so that the lower opening 2b serves as the water intake 2f and the upper opening 2a serves as the water discharge 2g. In FIG. 3, elements corresponding to those shown in FIG. 1 are given the same reference numerals.

In the water purification method using the water purification device 1 according to the second embodiment, the water supply step is a step of supplying water by the pump mechanism 3 so that the lower opening 2b serves as the water intake 2f and the upper opening 2a serves as the water discharge 2g. According to this water supply step, water from the bottom layer 10b is taken into the pipe 2 from the lower opening 2b and discharged from the upper opening 2a in the surface layer 10a, so that the oxygen-rich water from the surface layer 10a can be gradually supplied to the bottom layer 10b by convection, and oxygen can be efficiently supplied to the bottom layer 10b.

In addition, according to the control step, the flow rate of the pump mechanism 3 is limited so that the difference between the measured value in the internal temperature measurement step and the measured value in the external temperature measurement step falls within the predetermined range. This allows water to be pumped while thoroughly reducing the temperature difference between the inside and outside of the pipe 2, and therefore the density difference, due to heat transfer from the outside of the pipe 2 to the inside of the pipe 2 through the pipe 2. Therefore, the sinking force acting on the water being pumped due to the density difference, which is a load when pumping water, can be thoroughly reduced, so that the pump mechanism 3 can be operated efficiently with low load and low power. In addition, since there is almost no pressure difference between the inside and outside of the pipe 2 by flowing water slowly, the pipe 2 can be made of a flexible material. In addition, if the temperature difference (density difference) between the water coming out of the water outlet 2g and the water around the water outlet 2g is small, the water coming out of the water outlet 2g is less likely to fall again and is more likely to remain on the surface layer 10a.

Other aspects are the same as in the water purification method using the water purification device 1 of the first embodiment.

The above-described embodiment is an example of the present disclosure, and it goes without saying that various modifications are possible.

For example, the water purification device 1 and water purification method according to the above-described embodiment can be modified in various ways, as described below.

The water purification device 1 according to the embodiment described above can be modified in various ways as long as it has a pipe 2 with an upper opening 2a located in the surface layer 10a of the water area 10 and a lower opening 2b located in the bottom layer 10b of the water area 10, and a pump mechanism 3 provided in the pipe 2 for sending water so that one of the upper opening 2a and the lower opening 2b serves as a water intake 2f and the other of the upper opening 2a and the lower opening 2b serves as a water discharge 2g.

However, it is preferable that the water purification device 1 has an internal temperature sensor 4 that measures the temperature of the water inside the pipe 2 at a predetermined depth, an external temperature sensor 5 that measures the temperature of the water outside the pipe 2 at the predetermined depth, and a control unit 6 that controls the flow rate of the pump mechanism 3 so that the difference between the measurements by the internal temperature sensor 4 and the external temperature sensor 5 falls within a predetermined range.

It is also preferable that the internal temperature sensor 4 and the external temperature sensor 5 measure the temperature of the water at the water outlet 2g.

The pump mechanism 3 preferably has a throttling section 3a that reduces the cross-sectional area of the flow path in the pipe 2, an impeller 3b that is disposed in the throttling section 3a, and an electric motor 3c that rotates the impeller 3b.

In addition, it is preferable that the control unit 6 controls the flow rate of the pump mechanism 3 to a larger flow rate set without relying on the internal temperature sensor 4 and the external temperature sensor 5, and then reduces the flow rate of the pump mechanism 3 so that the difference between the measurement value obtained by the internal temperature sensor 4 and the measurement value obtained by the external temperature sensor 5 falls within the predetermined range.

The water purification method according to the embodiment described above can be modified in various ways, so long as it includes an arrangement step of arranging a pipe 2 having an upper opening 2a and a lower opening 2b and a pump mechanism 3 installed therein so that the upper opening 2a is located within the surface layer 10a of the water area 10 and the lower opening 2b is located within the bottom layer 10b of the water area 10, and a water supply step of supplying water by the pump mechanism 3 so that one of the upper opening 2a and the lower opening 2b is a water intake 2f and the other of the upper opening 2a and the lower opening 2b is a water discharge 2g.

However, it is preferable that the water supply step includes an internal temperature measurement step for measuring the temperature of the water inside the pipe 2 at a predetermined depth, an external temperature measurement step for measuring the temperature of the water outside the pipe 2 at the predetermined depth, and a control step for controlling the flow rate of the pump mechanism 3 so that the difference between the measurement value obtained by the internal temperature measurement step and the measurement value obtained by the external temperature measurement step falls within a predetermined range.

In addition, in the internal temperature measurement step and the external temperature measurement step, it is preferable to measure the temperature of the water at the water outlet 2g.

In addition, in the control step, it is preferable to control the flow rate of the pump mechanism 3 to a larger flow rate that is set regardless of the internal temperature measurement step and the external temperature measurement step, and then reduce the flow rate of the pump mechanism 3 so that the difference between the measurement value in the internal temperature measurement step and the measurement value in the external temperature measurement step falls within the predetermined range.

REFERENCE SIGNS LIST 1 Water purification device 2 Pipe 2a Upper opening 2b Lower opening 2c Lower end 2d Upper end 2e Upper end surface 2f Water intake 2g Water discharge 3 Pump mechanism 3a Throttle section 3b Impeller 3c Electric motor 4 Internal temperature sensor 5 External temperature sensor 6 Control section 6a Computer 6b Driver 7 Power supply 8 Float 9 Anchor 9a Linear member 10 Water area 10a Surface layer 10b Bottom layer 10c Water surface 10d Bottom surface 11 Wiring

Claims (5)

a pipe having an upper opening disposed within a surface layer of a body of water and a lower opening disposed within a bottom layer of said body of water;
a pump mechanism provided in the pipe for pumping water so that one of the upper opening and the lower opening serves as a water intake and the other of the upper opening and the lower opening serves as a water discharge ;
an internal temperature sensor for measuring the temperature of the water in the pipe at a predetermined depth;
an external temperature sensor for measuring the temperature of the water outside the pipe at the predetermined water depth;
a control unit that controls the flow rate of the pump mechanism so that the difference between the measurement value obtained by the internal temperature sensor and the measurement value obtained by the external temperature sensor falls within a predetermined range of ±5°C . The water purification device according to claim 1, wherein the control unit controls the flow rate of the pump mechanism to a set flow rate without relying on the internal temperature sensor and the external temperature sensor, and then controls the flow rate of the pump mechanism to be reduced so that the difference between the measurement value by the internal temperature sensor and the measurement value by the external temperature sensor falls within the specified range. The water purification device according to claim 1 or 2 , wherein the internal temperature sensor and the external temperature sensor measure the temperature of the water at the water outlet. The water purification device according to any one of claims 1 to 3, wherein the pump mechanism includes a throttle section that reduces the cross-sectional area of the flow path in the pipe, an impeller disposed in the throttle section, and an electric motor that rotates the impeller. a placement step of placing a pipe having an upper opening and a lower opening, the pipe having a pump mechanism therein, such that the upper opening is located within a surface layer of the water body and the lower opening is located within a bottom layer of the water body;
a water supply step of supplying water by the pump mechanism so that one of the upper opening and the lower opening serves as a water intake port and the other of the upper opening and the lower opening serves as a water discharge port;
The water purification method includes an internal temperature measurement step of measuring the temperature of water inside the pipe at a predetermined depth, an external temperature measurement step of measuring the temperature of water outside the pipe at the predetermined depth, and a control step of controlling the flow rate of the pump mechanism so that the difference between the measurement value obtained by the internal temperature measurement step and the measurement value obtained by the external temperature measurement step falls within a predetermined range of ±5°C .

Images