Water Treatment Systems

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

[Technical field]

[0001] The present invention relates to a water treatment system. [Background technology]

[0002] Water treatment systems that purify water using reverse osmosis membranes are widely used. When microorganisms are present in the supply water, they grow on the surface of the reverse osmosis membrane and produce slime (also called biofilm), which can reduce the treatment capacity of the reverse osmosis membrane equipment and cause damage to the reverse osmosis membrane.

[0003] Although slime control agents can be added to the feed water, the chlorine contained in the slime control agents can damage the reverse osmosis membrane, so it is necessary to remove the chlorine using activated carbon filters or reducing agents before feeding the water to the reverse osmosis membrane device.

[0004] Also, a water treatment system has been proposed in which an ultraviolet sterilization device is provided in the supply water tank (for example, see Patent Document 1). By irradiating the supply water with ultraviolet rays using the ultraviolet sterilization device, microorganisms in the supply water can be inactivated, thereby preventing the proliferation of microorganisms in the reverse osmosis membrane device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2011-36809 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in order to sufficiently inactivate microorganisms in the supply water by irradiating the supply water tank with ultraviolet light, which stores a certain amount of supply water, it is necessary to increase the output of ultraviolet light, which makes it difficult to completely prevent microorganisms from entering the reverse osmosis membrane device.

[0007] Therefore, an object of the present invention is to provide a water treatment system capable of suppressing the proliferation of microorganisms in a reverse osmosis membrane device. [Means for solving the problem]

[0008] A water treatment system according to one embodiment of the present invention comprises a reverse osmosis membrane device having a reverse osmosis membrane and separating supply water into treated water and concentrated water, a water supply line that supplies the supply water to the reverse osmosis membrane device, a chemical 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 supply water downstream of 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 sterilization device provided downstream of the injection point of the slime control agent in the water supply line and having an ultraviolet light source that irradiates ultraviolet light onto the supply water, and an irradiation control unit that turns on the ultraviolet light source for the ultraviolet sterilization device in accordance with the detection value of the concentration detector.

[0009] In the above-described water treatment system, the reverse osmosis membrane device can perform normal operation to mainly produce the treated water from the supply water, and the irradiation control unit can turn on or blink the ultraviolet light source during the normal operation of the reverse osmosis membrane device when the detection value of the concentration detector becomes small.

[0010] The above-mentioned water treatment system may further include a water supply pump provided in the water supply line, and a circulating water line that returns a portion of the concentrated water flowing out from the reverse osmosis membrane device to the upstream side of the water supply pump in the water supply line, and the concentration detector may be provided upstream of the confluence of the water supply line with the circulating water line, and the ultraviolet sterilization device may be provided downstream of the confluence of the water supply line with the circulating water line. Effect of the Invention

[0011] According to the present invention, it is possible to provide a water treatment system capable of suppressing the proliferation of microorganisms in a reverse osmosis membrane device. [Brief description of the drawings]

[0012] [Figure 1] 1 is a diagram showing a configuration of a water treatment system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a diagram showing the configuration of a water treatment system 1 of the present invention.

[0014] The water treatment system 1 of this embodiment includes a reverse osmosis membrane device 10 having a reverse osmosis membrane and separating supply water into treated water and concentrated water, a water supply line 20 that supplies supply water to the reverse osmosis membrane device 10, a treated water line 30 that guides the treated water flowing out from the reverse osmosis membrane device 10 to a demand destination, a circulating water line 40 that returns a portion of the concentrated water flowing out from the reverse osmosis membrane device 10 to the water supply line 20, and a control device 50 that controls the operation of each component.

[0015] The reverse osmosis membrane device 10 separates the feed water into treated water that has permeated the reverse osmosis membrane and concentrated water that has not permeated the reverse osmosis membrane by using a reverse osmosis membrane. The water treatment system 1 may include an ambient temperature sensor that detects the ambient temperature of the reverse osmosis membrane device 10, i.e., the temperature of the air surrounding the reverse osmosis membrane device 10.

[0016] The water supply line 20 is provided with a chemical injection device 21 that injects a slime control agent, an ultraviolet sterilization device 22 that irradiates the supply water with ultraviolet rays, and a water supply pump 23 that pressurizes the supply water and supplies it to the reverse osmosis membrane device 10. The water supply line 20 is also provided with a concentration detector 24 that detects the residual concentration of the active ingredient of the slime control agent, and a supply water flow meter 25 that detects the flow rate of the supply water supplied to the reverse osmosis membrane device 10.

[0017] The chemical injection device 21 reduces the activity of microorganisms in the supply water by injecting a slime control agent into the supply water. This makes it possible to suppress the generation of slime caused by the proliferation of microorganisms that have entered the reverse osmosis membrane device 10 on the membrane surface of the reverse osmosis membrane, thereby suppressing biofouling, which is the clogging of the reverse osmosis membrane by slime.

[0018] The slime control agent generally used is a chemical that has an oxidizing effect and may deteriorate the reverse osmosis membrane of the reverse osmosis membrane device 10. For this reason, the amount of slime control agent injected by the chemical injection device 21 is set to an amount that will not cause an excess of slime control agent inside the reverse osmosis membrane device 10 to deteriorate the reverse osmosis membrane even if the quality of the raw water supplied to the water treatment system 1 changes.

[0019] The ultraviolet sterilization device 22 is provided between the junction of the water supply line 20 and the circulating water line 40 and the water supply pump 23, and has an ultraviolet light source that irradiates the supply water with ultraviolet rays. As the ultraviolet light source, a diode array light source having a plurality of ultraviolet light emitting diodes is suitably used.

[0020] The ultraviolet sterilization device 22 inactivates microorganisms present in the supply water by irradiating the supply water with ultraviolet rays. This makes it possible to suppress the generation of slime caused by the proliferation of microorganisms that have entered the reverse osmosis membrane device 10 on the membrane surface of the reverse osmosis membrane, and therefore makes it possible to prevent biofouling, in which the reverse osmosis membrane is clogged with slime, even if the amount of slime control agent used is reduced.

[0021] There are cases where microorganisms cannot be completely inactivated in the ultraviolet sterilization device 22, and where the supply water passes through the ultraviolet sterilization device 22 while the ultraviolet sterilization device 22 is not in operation. In these cases, microorganisms may invade the flow path from the ultraviolet sterilization device 22 to the reverse osmosis membrane device 10 or into the inside of the reverse osmosis membrane device 10. If there is no continuous intrusion of microorganisms, the proliferation of microorganisms on the membrane surface of the reverse osmosis membrane is not promoted. However, if the flow path from the ultraviolet sterilization device 22 to the reverse osmosis membrane device 10 is long, microorganisms may also proliferate in, for example, piping joints, and therefore it is desirable to shorten the flow path from the ultraviolet sterilization device 22 to the reverse osmosis membrane device 10.

[0022] The ultraviolet sterilization device 22 is preferably disposed upstream of the water supply pump 23. By disposing the ultraviolet sterilization device 22 upstream of the water supply pump 23, the ultraviolet sterilization device 22 is not required to have high pressure resistance, which makes it easier to design the ultraviolet sterilization device 22.

[0023] The concentration detector 24 is disposed so as to detect the residual concentration of the active ingredient of the slime control agent in the supply water downstream of 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 detection value of the concentration detector 24 serves as an index of microbial activity when the ultraviolet sterilization device 22 of the supply water supplied to the reverse osmosis membrane device 10 is stopped. More specifically, it can be evaluated that the higher the residual concentration of the active ingredient of the slime control agent detected by the concentration detector 24, the lower the microbial activity in the supply water supplied to the reverse osmosis membrane device 10 when the ultraviolet sterilization device 22 is stopped.

[0024] As in this embodiment, the concentration detector 24 is preferably provided upstream of the junction of the water supply line 20 with the circulating water line 40. This allows a more accurate detection of a deficiency in the amount of slime control agent injected relative to the quality of the raw water, allowing an accurate determination of whether or not the ultraviolet sterilization device 22 needs to be operated. The concentration detector 24 may also be provided downstream of the junction of the water supply line 20 with the circulating water line 40 so as to detect the amount of slime control agent remaining in the supply water introduced into the reverse osmosis membrane device 10. Furthermore, 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 passing through the reverse osmosis membrane.

[0025] 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 electrical conductivity sensor 32 for detecting the electrical conductivity of the treated water.

[0026] The circulating water line 40 returns a portion of the concentrated water to the water supply line 20 and discharges the remainder to the outside of the system. For this reason, the circulating water line 40 has an outflow section 41 that guides the concentrated water flowing out of the reverse osmosis membrane device 10, a return section 42 that guides a portion of the concentrated water from the outflow section 41 to the water supply line 20, and a discharge section 43 that discharges the remainder of the concentrated water from the outflow section 41.

[0027] The return section 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 returns a portion 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 contains an increased amount of active microorganisms due to the concentration of impurities in the reverse osmosis membrane device 10, by returning this concentrated water to the upstream side of the ultraviolet sterilizer 22 and inactivating the microorganisms with ultraviolet light, clogging of the reverse osmosis membrane due to slime generation in the reverse osmosis membrane device 10 (biofouling) can be effectively prevented.

[0028] The circulating water line 40 is provided with a concentrated water flow rate control valve 44 at the outlet 41 for adjusting the flow rate of the concentrated water flowing out from the reverse osmosis membrane device 10, and a discharge flow rate control valve 45 at the discharge section 43 for adjusting the flow rate of the concentrated water discharged outside the system.

[0029] The control device 50 includes a normal operation control unit 51 that causes the reverse osmosis membrane device 10 to perform normal operation in which it mainly produces treated water from supply water, a flushing control unit 52 that causes the reverse osmosis membrane device 10 to perform flushing operation, a recovery rate detection unit 53 that detects the recovery rate, which is the ratio of the flow rate of treated water to the flow rate of supply water, and an irradiation control unit 54 that turns on the ultraviolet light source of the ultraviolet sterilization device 22 in accordance with the detection value of the concentration detector 24.

[0030] The control device 50 can be realized by, for example, executing an appropriate program on a computer device having a CPU, memory, an input / output interface, etc. Each component of the control device 50 described above is a classification of the function of the control device 50, and does not necessarily have to be clearly distinguishable in terms of physical structure and program structure.

[0031] The normal operation control unit 51 controls normal operation for obtaining treated water. For example, the normal operation control unit 51 can be configured to perform feedback control of the opening degree of the concentrated water flow rate adjustment valve 44 so as to maintain the detection value of the electrical conductivity sensor 32 at a set value.

[0032] The flushing control unit 52 controls the flushing operation performed to wash away turbidity adhering to the reverse osmosis membrane, for example, by increasing the ratio of the flow rate of concentrated water to the flow rate of feed water at the end of normal operation. As an example, the flushing control unit 52 fully opens the concentrated water flow rate adjustment valve 44 to reduce the recovery rate of the reverse osmosis membrane device 10, that is, the flow rate of treated water relative to the flow rate of feed water. As a result, the amount of water flowing along the membrane surface of the reverse osmosis membrane becomes larger than the amount of water permeating the reverse osmosis membrane, so that the turbidity adhering to the membrane surface is peeled off and discharged into the circulating water line 40.

[0033] The flushing operation by the flushing control unit 52 is generally performed when normal operation is stopped. This is because, when concentrated water remains inside the reverse osmosis membrane device 10, inorganic components in the water are more likely to precipitate than when the water is flowing, so it is desirable to minimize the concentration of the water remaining inside the reverse osmosis membrane device 10. The flushing operation may also be performed when the stoppage time reaches a certain time, etc. This is to push out the inorganic components that have precipitated due to a long stoppage and to prevent the inorganic components that have precipitated from settling on the membrane surface of the reverse osmosis membrane.

[0034] The recovery rate detection unit 53 can be configured to calculate the recovery rate of the reverse osmosis membrane device 10 based on the detection values ​​of the feed water flow meter 25 and the treated water flow meter 31.

[0035] The irradiation control unit 54 turns on the ultraviolet light source in the ultraviolet sterilization device 22 according to the detection value of the concentration detector 24. By suppressing the injection amount of the slime control agent by the chemical injection device 21, deterioration of the reverse osmosis membrane can be prevented, while when the effect of the slime control agent is deemed insufficient, clogging due to the generation of slime can be prevented by inactivating microorganisms by the ultraviolet sterilization device 22. Furthermore, when the injection amount of the slime control agent is deemed sufficient, the irradiation control unit 54 does not allow the ultraviolet sterilization device 22 to irradiate ultraviolet light unnecessarily, thereby suppressing power consumption.

[0036] As a specific example, the irradiation control unit 54 may turn on or blink the ultraviolet light source during normal operation of 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 falls below a predetermined value, or may turn on or blink the ultraviolet light source during flushing operation of the reverse osmosis membrane device 10 when the detection value of the concentration detector 24 falls below a predetermined value, or may turn on or blink the ultraviolet light source during both normal operation and flushing operation of the reverse osmosis membrane device 10 when the detection value of the concentration detector 24 falls below the predetermined value.

[0037] The irradiation control unit 54 turns on or blinks the ultraviolet light source during normal operation in response to the detection value of the concentration detector 24, thereby reducing the activity of microorganisms flowing into the reverse osmosis membrane device 10 without consuming excessive power in the irradiation control unit 54, thereby suppressing clogging due to biofouling of the reverse osmosis membrane during normal operation. Also, the irradiation control unit 54 turns on or blinks the ultraviolet light source during flushing operation in response to the detection value of the concentration detector 24, thereby reducing the amount of microorganisms in the water retained inside the reverse osmosis membrane device 10 while operation is stopped without consuming excessive power, thereby suppressing clogging due to slime generation while operation is stopped.

[0038] Irradiation control unit 54 may change the amount of ultraviolet light from ultraviolet sterilization device 22 in response to the detection value of concentration detector 24. Specifically, irradiation control unit 54 may change the emission intensity of the ultraviolet light source of ultraviolet sterilization device 22 in response to the detection value of concentration detector 24, or may change the emission time (duty ratio) of the ultraviolet light source in response to the detection value of concentration detector 24.

[0039] Furthermore, the irradiation control unit 54 may change the amount of ultraviolet light depending on 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 concentrated water returned from the circulating water line 40 to the water supply line 20 decreases, and the flow rate of water passing through the ultraviolet sterilization device 22 decreases. Therefore, by reducing the amount of ultraviolet light in the ultraviolet sterilization device 22 when the recovery rate of the reverse osmosis membrane device 10 is high, it is possible to effectively suppress the proliferation of microorganisms while suppressing power consumption.

[0040] Although each preferred embodiment of the water treatment system of the present invention has been described above, the present invention is not limited to the above-described embodiments and can be modified as appropriate.

[0041] In the water treatment system of the present invention, not all of the sensors described in the above embodiments are required, and those that are not required for the control adopted may be omitted, and different sensors may be provided depending on the control adopted. [Explanation of symbols]

[0042] 1. Water Treatment System 10 Reverse osmosis membrane equipment 20 Water Supply Line 21 Chemical dosing device 22 Ultraviolet sterilizer 23 Water 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 42 Return Department 43 Discharge section 44 Concentrated water flow control valve 45 Discharge flow control valve 50 Control device 51 Normal operation control unit 52 Flushing control section 53 Recovery rate detection unit 54 Irradiation control unit

Claims

1. A reverse osmosis membrane device having a reverse osmosis membrane and separating the feed water into treated water and concentrated water; a water supply line for supplying the feed water to the reverse osmosis membrane device; A chemical 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 supply water downstream of 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 sterilization device provided downstream of the injection point of the slime control agent in the water supply line and having an ultraviolet light source that irradiates ultraviolet light to the supply water; An irradiation control unit that turns on the ultraviolet light source in the ultraviolet sterilization device in response to a detection value of the concentration detector; Equipped with The reverse osmosis membrane device can perform a normal operation of mainly producing the treated water from the supply water, The irradiation control unit turns off the ultraviolet light source when the detection value of the concentration detector is large, and turns on 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.

2. a water supply pump provided in the water supply line; a circulating water line for returning a portion of the concentrated water flowing out from the reverse osmosis membrane device to the upstream side of the feed water pump of the feed water line; Further equipped with the concentration detector is provided upstream of a junction of the water supply line and the circulating water line; The water treatment system according to claim 1 , wherein the ultraviolet sterilization device is provided downstream of a junction of the water supply line with the circulating water line.

Images