JP2022086143A - 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 chemical injection device 21 for injecting a slime control agent to the feed water line 20; a concentration detector 24 for detecting residual concentration of an active component of the slime control agent in the feed water on a downstream side from an injection point of the slime control agent in the feed water line 20 or in the concentrated water flowing out of the reverse osmosis membrane device 10; an ultraviolet sterilization device 22 which is provided on the downstream side from the injection point of the slime control agent in the feed water line 20 and has an ultraviolet light source which radiates ultraviolet light to the feed water; and a radiation control unit 54 for turning on the ultraviolet light source to the ultraviolet sterilization device 22 according to the detected value of the concentration detector 24.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. The line, a chemical injection device for injecting a slime control agent into the water supply line, and the concentrated water flowing out of the supply water or the back-penetration membrane device downstream of the injection point of the slime control agent in the water supply line. An ultraviolet sterilizer having a concentration detector for detecting the residual concentration of the active ingredient of the slime control agent and an ultraviolet light source provided downstream of the injection point of the slime control agent in the water supply line and irradiating the supplied water with ultraviolet rays. And an irradiation control unit that lights the ultraviolet light source in the ultraviolet sterilizer according to the detection value of the concentration detector.

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 has a smaller detection value of the concentration detector. If so, the ultraviolet light source may be turned on or blinked during the normal operation of the reverse osmosis membrane device.

The water treatment system described above comprises a 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 osmotic membrane device to the upstream side of the water supply pump of the water supply line. Further, the concentration detector is provided on the upstream side of the confluence of the circulating water lines of the water supply line, and the ultraviolet sterilizer is located on the downstream side of the confluence of the circulating water lines of the water supply line. It may be provided.

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 treatment system 1 may include an atmospheric temperature sensor that detects the atmospheric temperature of the reverse osmosis membrane device 10, that is, the temperature of the air around the reverse osmosis membrane device 10.

The water supply line 20 includes a chemical injection device 21 for injecting a slime control agent, an ultraviolet sterilizer 22 for irradiating the supply water with ultraviolet rays, and a water supply pump 23 for pressurizing the supply water and supplying it to the reverse osmosis membrane device 10. And are provided. Further, in the water supply line 20, a concentration detector 24 for detecting the residual concentration of the active ingredient of the slime control agent and a supply water flow meter 25 for detecting the flow rate of the supply water supplied to the reverse osmosis membrane device 10 are provided. It will be provided.

The chemical injection device 21 reduces the activity of microorganisms in the supply water by injecting a slime control agent into the supply water. As a result, the formation of slime due to the propagation of microorganisms that have entered the reverse osmosis membrane device 10 on the membrane surface of the reverse osmosis membrane can be suppressed, so that biofouling in which the reverse osmosis membrane is blocked by the slime can be suppressed.

As the slime control agent, a chemical having an oxidizing action and capable of deteriorating the reverse osmosis membrane of the reverse osmosis membrane apparatus 10 is generally used. Therefore, the injection amount of the slime control agent by the chemical injection device 21 is such that even if the quality of the raw water supplied to the water treatment system 1 changes, the slime control agent becomes excessive inside the reverse osmosis membrane device 10 and back-permeates. The amount is set so as not to deteriorate the deterioration of the film.

The ultraviolet sterilizer 22 is provided between the confluence of the circulating water line 40 of the water supply line 20 and the water supply pump 23, 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 22 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 microorganisms that have entered the reverse osmosis membrane device 10 on the membrane surface of the reverse osmosis membrane can be suppressed. Therefore, even if the amount of the slime control agent used is reduced, the reverse osmosis membrane is formed by the slime. It is possible to prevent obstructive biofouling.

The ultraviolet sterilizer 22 may not be able to completely inactivate microorganisms, or the supplied water may pass through the ultraviolet sterilizer 22 while the ultraviolet sterilizer 22 is inactive. In these cases, microorganisms may enter the flow path from the ultraviolet sterilizer 22 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 22 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 22 to the reverse osmosis membrane device 10.

The ultraviolet sterilizer 22 is preferably arranged on the upstream side of the water supply pump 23. By disposing the ultraviolet sterilizer 22 on the upstream side of the water supply pump 23, the ultraviolet sterilizer 22 is not required to have high pressure resistance, so that the design of the ultraviolet sterilizer 22 becomes easy.

The concentration detector 24 is arranged to detect the residual concentration of the active ingredient of the slime control agent in the supply water downstream from the injection point of the slime control agent in the water supply line or in the concentrated water flowing out from the reverse osmosis membrane device 10. .. The detected value of the concentration detector 24 is an index of the activity of microorganisms when the ultraviolet sterilizing device 22 of the supplied water supplied to the reverse osmosis membrane device 10 is stopped. More specifically, the higher the residual concentration of the active ingredient of the slime control agent detected by the concentration detector 24, the lower the activity of microorganisms in the supply water supplied to the reverse osmosis membrane device 10 when the ultraviolet sterilizer 22 is stopped. It can be evaluated as possible.

It is preferable that the concentration detector 24 is provided on the upstream side of the confluence of the circulating water lines 40 of the water supply line 20 as in the present embodiment. As a result, it is possible to more accurately detect the shortage of the injection amount of the slime control agent with respect to the water quality of the raw water, so that it is possible to accurately determine whether or not the ultraviolet sterilizer 22 needs to be operated. Further, the concentration detector 24 is provided on the downstream side of the confluence point of the water supply line 20 with the circulating water line 40 so as to detect the residual amount of the slime control agent in the supply water introduced into the reverse osmosis membrane device 10. You may. Further, the concentration detector 24 may be provided in the circulating water line 40 when the slime control agent is concentrated in the concentrated water without penetrating the reverse osmosis membrane.

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 22 and the water supply pump 23 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 22 and the water supply pump 23 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 22 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 flow rate adjusting valve 44, which is provided in the outflow section 41 and adjusts the flow rate of the concentrated water flowing out from the reverse osmosis membrane device 10, and is provided in the discharge section 43 and is discharged to the outside of the system. A discharge flow rate adjusting valve 45 for adjusting the flow rate of the concentrated water is 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 an irradiation control unit 54 that lights an ultraviolet light source on the ultraviolet sterilizer 22 according to the detection value of the concentration detector 24. , Have.

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 44 so as to hold the detected value of the electric conductivity sensor 32 at the 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 44. 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 25 and the treated water flow meter 31.

The irradiation control unit 54 turns on the ultraviolet light source in the ultraviolet sterilizer 22 according to the detection value of the concentration detector 24. The deterioration of the reverse osmosis membrane is prevented by suppressing the injection amount of the slime control agent by the chemical injection device 21, and the microorganisms are inactivated by the ultraviolet sterilizer 22 when the effect of the slime control agent is considered to be insufficient. This can prevent clogging due to the formation of slime. Further, when the injection amount of the slime control agent is considered to be sufficient, the irradiation control unit 54 does not irradiate the ultraviolet sterilizer 22 with unnecessary ultraviolet rays, so that the power consumption can be suppressed.

As a specific example, the irradiation control unit 54 sets the reverse osmosis membrane device 10 when the detection value of the concentration detector 24 becomes small, specifically, when the detection value of the concentration detector 24 becomes a predetermined value or less. The ultraviolet light source may be turned on or blinked during normal operation, or the ultraviolet light source may be turned on or blinked during flushing operation of the reverse osmosis membrane device 10 when the detection value of the concentration detector 24 is equal to or less than a predetermined value. Frequently, when the detection value of the concentration detector 24 is equal to or less than a predetermined value, the ultraviolet light source may be turned on or blinked in both the normal operation and the flushing operation of the reverse osmosis membrane device 10.

By turning on or blinking the ultraviolet light source during normal operation according to the detection value of the concentration detector 24, the irradiation control unit 54 flows into the reverse osmosis membrane device 10 without consuming excessive power in the irradiation control unit 54. Since the activity of microorganisms is reduced, clogging due to biofouling of the reverse osmosis membrane during normal operation can be suppressed. Further, the irradiation control unit 54 turns on or blinks the ultraviolet light source during the flushing operation according to the detection value of the concentration detector 24, so that the inside of the reverse osmosis membrane device 10 is stopped without consuming excessive power. Since the amount of microorganisms in the water that stays in the water can be reduced, clogging due to the production of slime during the shutdown can be suppressed.

The irradiation control unit 54 may change the amount of ultraviolet light of the ultraviolet sterilizer 22 according to the detection value of the concentration detector 24. Specifically, the irradiation control unit 54 may change the emission intensity of the ultraviolet light source of the ultraviolet sterilizer 22 according to the detection value of the concentration detector 24, and detect the emission time (duty ratio) of the ultraviolet light source. It may be changed according to the detection value of the device 24.

Further, the irradiation control unit 54 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 22 decreases. Therefore, when the recovery rate of the reverse osmosis membrane device 10 is high, the amount of ultraviolet light in the ultraviolet sterilizer 22 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 osmotic membrane device 20 Water supply line 21 Chemical injection device 22 Ultraviolet sterilization device 23 Water supply pump 24 Concentration detector 25 Supply water flow meter 30 Treated water line 31 Treated water flow meter 32 Electrical conductivity sensor 40 Circulating water line 41 Outflow unit 42 Return unit 43 Discharge unit 44 Concentrated water flow rate adjustment valve 45 Discharge flow rate adjustment valve 50 Control device 51 Normal operation control unit 52 Flushing control unit 53 Time rate detection unit 54 Irradiation control unit

Claims (3)

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,
A medicinal injection device that injects a slime control agent into the water supply line,
A concentration detector that detects the residual concentration of the active ingredient of the slime control agent in the feed water downstream from the injection point of the slime control agent in the water supply line or in the concentrated water flowing out from the reverse osmosis membrane device.
An ultraviolet sterilizer provided on the downstream side of the injection point of the slime control agent in the water supply line and having an ultraviolet light source for irradiating the supplied water with ultraviolet rays.
An irradiation control unit that lights the ultraviolet light source on the ultraviolet sterilizer according to the detection value of the concentration detector, and
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 detection value of the concentration detector becomes small. 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.
Further prepare
The concentration detector is provided on the upstream side of the confluence of the circulating water line of the water supply line.
The water treatment system according to claim 1 or 2, wherein the ultraviolet sterilizer is provided on the downstream side of the confluence of the circulating water lines of the water supply line.

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