JP2022086142A - Water treatment system - Google Patents

Abstract

To provide a water treatment system capable of suppressing proliferation of microorganisms in a reverse osmosis membrane device.SOLUTION: There is provided a water treatment system 1 which comprises: a reverse osmosis membrane device 10 which has a reverse osmosis membrane and separates feed water into treated water and concentrated water; a feed water line 20 for supplying the feed water to the reverse osmosis membrane device 10; a feed water pump 22 installed in the feed water line; a circulation water line 40 for returning a part of concentrated water flowing out of the reverse osmosis membrane device 10 to an upstream side of the feed water pump 22 in the feed water line 20; an ultraviolet sterilization device 21 which is installed between a confluence point of the circulation water line 40 in the feed water line 20 and the feed water pump 22 and has an ultraviolet light source which radiates ultraviolet light to the feed water; a clogging index detection unit 54 for detecting a clogging index indicating a clogging degree of the reverse osmosis membrane; and a radiation control unit 55 for turning on the ultraviolet light source to the ultraviolet sterilization device 21 according to the detected value of the clogging index detection section 54.SELECTED DRAWING: Figure 1

Description

The present invention relates to a water treatment system.

A water treatment system that purifies water using a reverse osmosis membrane is widely used. When microorganisms are contained in the feed water, the microorganisms propagate on the surface of the reverse osmosis membrane to generate slime (also called biofilm), which reduces the processing capacity of the reverse osmosis membrane device or damages the reverse osmosis membrane. May cause.

There is also a method of adding a slime control agent to the feed water, but chlorine contained in the slime control agent can damage the reverse osmosis membrane. Therefore, it is necessary to remove chlorine by using an activated carbon filtration device or a reducing agent before supplying the reverse osmosis membrane device.

Further, a water treatment system in which an ultraviolet sterilizer is provided in a supply water tank has also been proposed (see, for example, Patent Document 1). By irradiating the supplied water with ultraviolet rays using an ultraviolet sterilizer, the microorganisms in the supplied water can be inactivated, so that the growth of the microorganisms in the reverse osmosis membrane device can be prevented.

Japanese Unexamined Patent Publication No. 2011-36809

However, in order to sufficiently inactivate the microorganisms in the supply water by irradiating the supply water tank that stores a certain amount of supply water with ultraviolet rays, it is necessary to increase the output of the ultraviolet rays. Therefore, it is difficult to completely prevent microorganisms from entering the reverse osmosis membrane device.

Therefore, an object of the present invention is to provide a water treatment system capable of suppressing the growth of microorganisms in a reverse osmosis membrane device.

The water treatment system according to one aspect of the present invention has a back-penetrating membrane, a back-penetrating membrane device that separates the supplied water into treated water and concentrated water, and a water supply that supplies the supplied water to the back-penetrating membrane device. A line, a water supply pump provided in the water supply line, a circulating water line that recirculates a part of the concentrated water flowing out from the back-penetrating membrane device to the upstream side of the water supply pump of the water supply line, and the water supply line. An ultraviolet sterilizer provided between the confluence of the circulating water line and the water supply pump and having an ultraviolet light source that irradiates the supply water with ultraviolet rays, and a clogging index that detects a clogging index indicating the degree of clogging of the back-penetrating film. A detection unit and an irradiation control unit for lighting the ultraviolet light source in the ultraviolet sterilizer according to the detection value of the clogging index detection unit are provided.

In the above-mentioned water treatment system, the reverse osmosis membrane device can perform a normal operation in which the treated water is mainly generated from the supply water, and the irradiation control unit can perform a normal operation when the clogging index exceeds a predetermined value. The ultraviolet light source may be turned on or blinked during the normal operation of the reverse osmosis membrane device.

In the above-mentioned water treatment system, the reverse osmosis membrane device can perform a flushing operation to wash away turbidity adhering to the reverse osmosis membrane by increasing the ratio of the flow rate of the concentrated water to the flow rate of the supply water. When the clogging index exceeds a predetermined value, the irradiation control unit may turn on or blink the ultraviolet light source during the flushing operation of the reverse osmosis membrane device.

In the above-mentioned water treatment system, a recovery rate detection unit for detecting a recovery rate which is a ratio of the flow rate of the treated water to the flow rate of the supply water is further provided, and the irradiation control unit includes the ultraviolet rays according to the recovery rate. The amount of light may be changed.

In the water treatment system described above, the clogging index may be the differential pressure between the reverse osmosis membranes or the permeation flux of the reverse osmosis membranes.

According to the present invention, it is possible to provide a water treatment system capable of suppressing the growth of microorganisms in a reverse osmosis membrane apparatus.

It is a figure which shows the structure of the water treatment system which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the configuration of the water treatment system 1 of the present invention.

The water treatment system 1 of the present embodiment has a back-penetrating film, a back-penetrating film device 10 that separates the supplied water into treated water and concentrated water, and a water supply line 20 that supplies the supplied water to the back-penetrating film device 10. A treated water line 30 that guides the treated water flowing out of the back-penetrating membrane device 10 to a demand destination, and a circulating water line 40 that returns a part of the concentrated water flowing out of the back-penetrating membrane device 10 to the water supply line 20. A control device 50 for controlling the operation of each component is provided.

The reverse osmosis membrane device 10 separates the supplied water into a treated water that has permeated the reverse osmosis membrane and a concentrated water that has not permeated the reverse osmosis membrane by membrane separation using the reverse osmosis membrane.

The water supply line 20 is provided with an ultraviolet sterilizer 21 that irradiates the supplied water with ultraviolet rays, and a water supply pump 22 for pressurizing the supplied water and supplying it to the reverse osmosis membrane device 10. Further, in the water supply line 20, a supply water pressure sensor 23 for detecting the pressure of the supply water, a supply water flow meter 24 for detecting the flow rate of the supply water, and a supply water temperature sensor 25 for detecting the temperature of the supply water are provided. Is provided.

The ultraviolet sterilizer 21 is provided between the confluence of the circulating water line 40 of the water supply line 20 and the water supply pump 22, and has an ultraviolet light source that irradiates the supplied water with ultraviolet rays. As the ultraviolet light source, a diode array light source having a plurality of ultraviolet light emitting diodes is preferably used.

The ultraviolet sterilizer 21 inactivates microorganisms existing in the supply water by irradiating the supply water with ultraviolet rays. As a result, the formation of slime due to the propagation of the microorganisms that have entered the reverse osmosis membrane device 10 on the membrane surface of the reverse osmosis membrane can be suppressed, so that the membrane clogging in which the reverse osmosis membrane is blocked by the slime can be prevented.

The ultraviolet sterilizer 21 may not be able to completely inactivate microorganisms, or the supplied water may pass through the ultraviolet sterilizer 21 while the ultraviolet sterilizer 21 is inactive. In these cases, microorganisms may enter the flow path from the ultraviolet sterilizer 21 to the reverse osmosis membrane device 10 or the inside of the reverse osmosis membrane device 10. If there is no continuous invasion of microorganisms, the growth of microorganisms on the membrane surface of the reverse osmosis membrane will not be promoted, but if the flow path from the ultraviolet sterilizer 21 to the reverse osmosis membrane device 10 becomes long, for example, the piping Since microorganisms can propagate in joints and the like, it is desirable to shorten the flow path from the ultraviolet sterilizer 21 to the reverse osmosis membrane device 10.

The ultraviolet sterilizer 21 is preferably arranged on the upstream side of the water supply pump 22. By disposing the ultraviolet sterilizer 21 on the upstream side of the water supply pump 22, high pressure resistance is not required for the ultraviolet sterilizer 21, so that the design of the ultraviolet sterilizer 21 becomes easy.

The treated water line 30 is provided with a treated water flow meter 31 for detecting the flow rate of the treated water and an electric conductivity sensor 32 for detecting the electric conductivity of the treated water.

The circulating water line 40 recirculates a part of the concentrated water to the water supply line 20 and discharges the rest to the outside of the system. Therefore, the circulating water line 40 includes an outflow section 41 that guides the concentrated water flowing out from the reverse osmosis membrane device 10, a return section 42 that guides a part of the concentrated water from the outflow section 41 to the water supply line 20, and an outflow section 41. It has a discharge unit 43 for discharging the balance of concentrated water from the water.

The return unit 42 is connected to the upstream side of the ultraviolet sterilizer 21 and the water supply pump 22 of the water supply line 20. Therefore, the circulating water line 40 recirculates a part of the concentrated water to the upstream side of the ultraviolet sterilizer 21 and the water supply pump 22 of the water supply line 20. In particular, since the concentrated water also has an increased content of active microorganisms due to the concentration of impurities in the reverse osmosis membrane device 10, the concentrated water is returned to the upstream side of the ultraviolet sterilizer 21 and is subjected to ultraviolet rays. By inactivating microorganisms, clogging (biofouling) of the reverse osmosis membrane due to slime formation in the reverse osmosis membrane device 10 can be effectively prevented.

The circulating water line 40 is provided with a concentrated water pressure sensor 44 provided in the outflow section 41 to detect the pressure of the concentrated water flowing out from the reverse osmosis membrane device 10, and is provided in the outflow section 41 and flows out from the reverse osmosis membrane device 10. A concentrated water flow rate adjusting valve 45 for adjusting the flow rate of the concentrated water to be used and a discharge flow rate adjusting valve 46 provided in the discharge unit 43 for adjusting the flow rate of the concentrated water discharged to the outside of the system are provided.

The control device 50 includes a normal operation control unit 51 that causes the reverse osmosis membrane device 10 to perform a normal operation mainly for generating treated water from supply water, and a flushing control unit 52 that causes the reverse osmosis membrane device 10 to perform a flushing operation. A recovery rate detection unit 53 that detects the recovery rate, which is the ratio of the flow rate of the treated water to the flow rate of the supply water, and a clogging index detection unit 54 that detects a clogging index indicating the degree of blockage of the reverse osmosis membrane of the reverse osmosis membrane device 10. It also has an irradiation control unit 55 that turns on an ultraviolet light source in the ultraviolet sterilizer 21 according to the detection value of the clogging index detection unit 54.

The control device 50 can be realized by, for example, causing a computer device having a CPU, a memory, an input / output interface, and the like to execute an appropriate program. Each component of the above-mentioned control device 50 categorizes the functions of the control device 50, and may not be clearly distinguishable in the physical structure and the program structure.

The normal operation control unit 51 controls the normal operation for obtaining the treated water. As an example, the normal operation control unit 51 may be configured to feedback control the opening degree of the concentrated water flow rate adjusting valve 45 so as to hold the detected value of the electric conductivity sensor 32 at a set value.

The flushing control unit 52 controls the flushing operation performed to wash away the turbidity adhering to the reverse osmosis membrane by increasing the ratio of the flow rate of the concentrated water to the flow rate of the supply water, for example, at the end of the normal operation. As an example, the flushing control unit 52 reduces the recovery rate of the reverse osmosis membrane device 10, that is, the flow rate of the treated water with respect to the flow rate of the supply water, by fully opening the concentrated water flow rate adjusting valve 45. As a result, the amount of water flowing along the membrane surface of the reverse osmosis membrane is larger than the amount of water penetrating the reverse osmosis membrane, so that the turbidity adhering to the membrane surface is peeled off and discharged to the circulating water line 40.

The flushing operation by the flushing control unit 52 is generally performed when the normal operation is stopped. This is because when concentrated water stays inside the reverse osmosis membrane device 10, inorganic components in the water are more likely to precipitate than when water is flowing, so that the water staying inside the reverse osmosis membrane device 10 is more likely to precipitate. This is because it is desired to reduce the degree of concentration as much as possible. Further, the flushing operation may be performed even when the stop time reaches a certain time. This is to prevent the precipitated inorganic component from being fixed on the membrane surface of the reverse osmosis membrane by extruding the precipitated inorganic component after a long stop.

The recovery rate detection unit 53 may be configured to calculate the recovery rate of the reverse osmosis membrane device 10 based on the detection values of the supply water flow meter 24 and the treated water flow meter 31.

The clogging index detection unit 54 is based on, for example, detection values of a supply water pressure sensor 23, a supply water flow meter 24, a supply water temperature sensor 25, a treated water flow meter 31, an electric conductivity sensor 32, a concentrated water pressure sensor 44, and the like. It is possible to calculate a clogging index indicating the degree of obstruction of the back-penetrating membrane. Specific clogging indicators include differential pressure between reverse osmosis membranes (pressure loss occurring in water flowing along the reverse osmosis membrane) that can be calculated as the difference between the detected values of the supply water pressure sensor 23 and the concentrated water pressure sensor 44, and treatment. A permeation flux (permeated water amount per unit area) of a reverse osmosis membrane that can be calculated from the detected value of the water flow meter 31 or the like can be used. The value of the clogging index is not limited to a numerical value represented by a well-known unit system such as an SI unit, and may be any value that can be converted into a numerical value of a desired unit system. The clogging index detecting unit 54 may further use a value obtained by correcting these values with the water temperature, that is, a value assumed when the water temperature is a predetermined value and other conditions are the same, as the clogging index.

The irradiation control unit 55 turns on the ultraviolet light source in the ultraviolet sterilizer 21 according to the detection value of the clogging index detection unit 54. In this way, the irradiation control unit 55 turns on or blinks the ultraviolet light source according to the value of the clogging index to suppress clogging due to the generation of slime, and unnecessary irradiation of ultraviolet rays is not performed, so that power consumption can be suppressed. ..

As a specific example, the irradiation control unit 55 may turn on or blink the ultraviolet light source during the normal operation of the reverse osmosis membrane device 10 when the clogging index exceeds a predetermined value, and reverse when the clogging index exceeds a predetermined value. The ultraviolet light source may be turned on or blinked during the flushing operation of the osmosis membrane device 10, and when the clogging index exceeds a predetermined value, the ultraviolet light source is turned on or blinked in both the normal operation and the flushing operation of the reverse osmosis membrane device 10. You may.

By turning on or blinking the ultraviolet light source during normal operation according to the value of the clogging index, the irradiation control unit 55 can reduce the amount of microorganisms newly flowing into the reverse osmosis membrane device 10 without consuming excessive power. Therefore, clogging due to the formation of slime on the membrane surface of the reverse osmosis membrane can be suppressed. Further, the irradiation control unit 55 turns on or blinks the ultraviolet light source during the flushing operation according to the value of the clogging index, so that the ultraviolet light source stays inside the reverse osmosis membrane device 10 while the operation is stopped without consuming excessive power. Since the amount of microorganisms in the water can be reduced, clogging due to the production of slime during shutdown can be suppressed.

The irradiation control unit 55 may change the amount of ultraviolet light (emission intensity of the ultraviolet light source) of the ultraviolet sterilizer 21 according to the value of the clog index, and set the emission time (duty ratio) of the ultraviolet light source to the value of the clog index. It may be changed accordingly.

Further, the irradiation control unit 55 may change the amount of ultraviolet light according to the recovery rate of the reverse osmosis membrane device 10 detected by the recovery rate detection unit 53. When the recovery rate of the reverse osmosis membrane device 10 is high, the flow rate of the concentrated water returned from the circulating water line 40 to the water supply line 20 becomes small, so that the flow rate of water passing through the ultraviolet sterilizer 21 decreases. Therefore, when the recovery rate of the reverse osmosis membrane device 10 is high, the amount of ultraviolet light in the ultraviolet sterilizer 21 can be reduced to effectively suppress the growth of microorganisms and suppress the power consumption.

Although the preferred embodiments of the water treatment system of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be appropriately modified.

In the water treatment system of the present invention, not all the sensors described in the above-described embodiment are required, and those not required for the control to be adopted may be omitted, and the sensors differ depending on the control to be adopted. May be provided.

1 Water treatment system 10 Reverse permeation membrane device 20 Water supply line 21 Ultraviolet sterilizer 22 Water supply pump 23 Supply water pressure sensor 24 Supply water flow meter 25 Supply water temperature sensor 30 Treated water line 31 Treated water flow meter 32 Electrical conductivity sensor 40 Circulation Water line 41 Outflow unit 42 Return unit 43 Discharge unit 44 Concentrated water pressure sensor 45 Concentrated water flow rate adjustment valve 46 Discharge flow rate adjustment valve 50 Control device 51 Normal operation control unit 52 Flushing control unit 53 Time yield detection unit 54 Clog index detection unit 55 Irradiation control unit

Claims (5)

A reverse osmosis membrane device that has a reverse osmosis membrane and separates the supplied water into treated water and concentrated water.
A water supply line that supplies the supply water to the reverse osmosis membrane device,
The water supply pump provided in the water supply line and
A circulating water line that recirculates a part of the concentrated water flowing out of the reverse osmosis membrane device to the upstream side of the water supply pump of the water supply line.
An ultraviolet sterilizer provided between the confluence of the circulating water line of the water supply line and the water supply pump and having an ultraviolet light source for irradiating the supply water with ultraviolet rays.
A clogging index detecting unit that detects a clogging index indicating the degree of blockage of the reverse osmosis membrane, and a clogging index detecting unit.
An irradiation control unit that lights the ultraviolet light source on the ultraviolet sterilizer according to the detection value of the clogging index detection unit.
A water treatment system. The reverse osmosis membrane device can perform a normal operation in which the treated water is mainly generated from the supply water.
The water treatment system according to claim 1, wherein the irradiation control unit lights or blinks the ultraviolet light source during the normal operation of the reverse osmosis membrane device when the clogging index exceeds a predetermined value. The reverse osmosis membrane device can perform a flushing operation to wash away turbidity adhering to the reverse osmosis membrane by increasing the ratio of the flow rate of the concentrated water to the flow rate of the supply water.
The water treatment system according to claim 1 or 2, wherein the irradiation control unit lights or blinks the ultraviolet light source during the flushing operation of the reverse osmosis membrane device when the clogging index exceeds a predetermined value. Further, a recovery rate detection unit for detecting a recovery rate which is a ratio of the flow rate of the treated water to the flow rate of the supply water is provided.
The water treatment system according to any one of claims 1 to 3, wherein the irradiation control unit changes the amount of ultraviolet light according to the recovery rate. The water treatment system according to any one of claims 1 to 4, wherein the clogging index is a differential pressure between the reverse osmosis membranes or a permeation flux of the reverse osmosis membranes.

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