JP7396124B2 - water treatment system - Google Patents

Description

The present invention relates to water treatment systems.

In water treatment systems that perform membrane filtration processes using reverse osmosis membranes, sodium hypochlorite is used as a chlorine-based disinfectant to remove microorganisms in order to suppress biofilms caused by the growth of microorganisms. There is.

For example, Patent Document 1 discloses a water production method using a reverse osmosis membrane, in which sodium hypochlorite is flowed into the reverse osmosis membrane in a water treatment system in order to suppress biofouling due to the generation of biofilm. The water production method is disclosed.

When water in which free chlorine is present by addition of a chlorine-based oxidizing agent or electrolysis is treated with a reverse osmosis membrane, the reverse osmosis membrane undergoes oxidative deterioration. For this reason, as disclosed in Patent Document 2, for example, there is a conventionally known technique for removing free chlorine by adding a reducing agent such as sodium bisulfite (SBS) or sodium sulfite at the front stage of the reverse osmosis membrane. There is.

Japanese Patent Application Publication No. 2016-190214 Japanese Patent Application Publication No. 7-308671

In order to prevent chlorine from remaining, the conventional method was to add an excessive amount of reducing agent, but if too much reducing agent is added, the oxidizing disinfectant decomposes and disappears after the reducing agent is added, leaving no disinfectant component. In some cases, the inside of the reverse osmosis membrane device is filled with a reducing agent, resulting in a reducing atmosphere, which promotes the formation of biofilms.

In addition, chlorine removal by a reducing agent varies depending on the mixability and water temperature after adding the reducing agent, so if the amount added is close to the residual chlorine concentration, there is a risk that chlorine will remain and cause deterioration of the reverse osmosis membrane. there were.

In addition, due to the addition of sodium bisulfite (SBS), sulfate ions in the water supply increase, which can lead to the proliferation of bacteria that use sulfate ions as a nutrient source, and the leakage of unreacted sulfite into treated water. There were concerns that the quality of treated water would deteriorate.

Furthermore, oxidizing disinfectants are added after chlorine has been removed with a reducing agent, but since the oxidizing disinfectant decomposes and disappears due to the excess reducing agent, it is necessary to add an excess of oxidizing disinfectant to account for the excess reducing agent. I needed to.

Therefore, an object of the present invention is to provide a water treatment system that can suppress the generation of biofilm in a reverse osmosis membrane and measure the deterioration of biofilm while preventing the harmful effects of reducing agents in removing free chlorine. do.

The present invention provides a reverse osmosis membrane module that separates filtered feed water into permeated water and concentrated water, a water supply line that supplies feed water to the reverse osmosis membrane module, and permeated water separated by the reverse osmosis membrane module. a permeated water line that sends out the concentrated water, a concentrated water line that sends out the concentrated water separated by the reverse osmosis membrane module, and a concentrated drainage line that discharges part or all of the concentrated water to the outside of the system as concentrated wastewater, A residual chlorine concentration measuring means for measuring the residual chlorine concentration in the water supply, a first chemical injection means for injecting a reducing agent into the water supply, a second chemical injection means for injecting a stabilizing agent into the water supply, and a chlorine at a predetermined concentration. and a reducing agent injection control means for controlling the injection of the reducing agent by the first chemical injection means so that the reducing agent remains in the water treatment system.

Further, in the above water treatment system, the reducing agent injection control means adjusts the predetermined concentration in stages so that the concentration of a reactant between residual chlorine in the water supply and the stabilizer becomes a predetermined value. It is preferable to do so.

Moreover, it is preferable that the above-mentioned water treatment system further includes a third chemical injection means for injecting another type of disinfectant into the water supply.

Preferably, the water treatment system further includes a stabilizer injection control means for controlling the stabilizing agent injection by the second chemical injection means so that chlorine does not remain in the water supply.

Further, the present invention provides a reverse osmosis membrane module that separates filtered feed water into permeated water and concentrated water, a filtered water line that supplies feed water to the reverse osmosis membrane module, and a reverse osmosis membrane module that separates the feed water into permeated water and concentrated water. a permeated water line that sends out the permeated water, a concentrated water line that sends out the concentrated water separated by the reverse osmosis membrane module, and a concentrated water line that sends out part or all of the concentrated water as concentrated wastewater to the outside of the system. A line, a residual chlorine concentration measuring means for measuring the residual chlorine concentration in the supply water, a first chemical injection means for injecting a reducing agent into the water supply, a second chemical injection means for injecting a stabilizer into the water supply, and reducing agent injection control means for controlling the first chemical injection control means so as to sometimes inject the reducing agent and stop the injection of the reducing agent during sterilization; The present invention relates to a water treatment system comprising a stabilizer chemical injection control means for controlling the second chemical injection control means so as to stop the injection and inject the stabilizer during sterilization treatment.

The above water treatment system also includes a fourth chemical injection means for injecting a chlorine-based oxidizing agent into the water supply, and a fourth chemical injection means for injecting the chlorine-based oxidizing agent into the water supply when the residual chlorine concentration is less than a predetermined value during sterilization treatment. Note: Oxidizing agent injection control that controls the fourth chemical injection means to reduce the amount of the chlorine-based oxidizing agent or to stop the chemical injection when the residual chlorine concentration is equal to or higher than a predetermined value. It is preferable to further include means.

Moreover, in the above water treatment system, it is preferable that the stabilizer contains a sulfamic acid compound.

Moreover, in the above water treatment system, it is preferable that the stabilizer further contains a bromine compound.

Further, in the water treatment system described above, it is preferable that the stabilizer further contains a halogen bonded to the sulfamic acid compound.

Moreover, it is preferable that the above-mentioned water treatment system further includes a fifth chemical injection means for chemically injecting a scale dispersant into the filtered water.

1 is an overall configuration diagram of a water treatment system according to a first embodiment of the present invention. FIG. 2 is a functional block diagram of a control unit included in the water treatment system according to the first embodiment of the present invention. FIG. 2 is an overall configuration diagram of a water treatment system according to a second embodiment of the present invention. It is a functional block diagram of the control part with which the water treatment system concerning a 2nd embodiment of the present invention is equipped. It is an overall block diagram of the water treatment system concerning a 3rd embodiment of the present invention. It is a functional block diagram of the control part with which the water treatment system concerning a 3rd embodiment of the present invention is equipped.

[1 First embodiment]
[1.1 Overall configuration]
Hereinafter, a water treatment system 1 according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of a water treatment system 1 of the present invention.

As shown in FIG. 1, the water treatment system 1 includes a residual chlorine concentration measuring device 5, a first chemical addition device 6, a second chemical addition device 7, a third chemical addition device 8, and a fourth chemical addition device. 9, a pressure pump 15, an inverter 16, a reverse osmosis membrane module (hereinafter also referred to as "RO membrane module") 17, a constant flow valve 18, a proportional control drain valve 19, and a control unit 30. Be prepared. Note that illustration of electrical connection lines between the control unit 30 and the controlled device is omitted.

The water treatment system 1 includes a water supply line L1, a permeated water line L2, a concentrated water line L3, a circulating water line L4, and a concentrated drainage line L5. "Line" is a general term for lines such as channels, routes, and pipes through which fluid can flow. In addition, regardless of its origin (source) or water quality, water flowing through the water supply line L1, concentrated water line L3, or circulating water line L4 is also referred to as "supply water", and the water flowing through the water supply line L1, concentrated water line L3, or circulating water line L4 is also referred to as "supply water", and the water flowing through the water supply line L1, concentrated water line L3, or circulating water line L4 is also referred to as "water supply", The water flowing through the drainage line L5 is also referred to as "concentrated water."

The water supply line L1 is a line that supplies water W11 and W12 toward the reverse osmosis membrane module 17. The water supply line L1 includes a first water supply line L11 and a second water supply line L12 from the upstream side to the downstream side.

The upstream end of the first water supply line L11 is connected to the water source 2 of the water supply W11. The downstream end of the first water supply line L11 is connected to the second water supply line L12 and the circulating water line L4 at a connecting portion J1. In the first water supply line L11, for example, a residual chlorine concentration measuring device 5, a first chemical addition device 6, a second chemical addition device 7, a third chemical addition device 8, and a fourth chemical addition device 9 are installed from the upstream side. They are provided in this order toward the downstream side.

Note that the water supply W11 may be treated water filtered by a filtration device (not shown) or tap water.

The residual chlorine concentration measuring device 5 measures the residual chlorine concentration in the water supply W11. In particular, the residual chlorine concentration measuring device 5 measures the total amount of free chlorine in the water supply W11 as the residual chlorine concentration. Further, the residual chlorine concentration measuring device 5 can measure the residual chlorine concentration by having a configuration similar to the chlorine concentration sensor disclosed in, for example, JP-A-2018-038942. The residual chlorine concentration measuring device 5 is electrically connected to the control section 30.

The first chemical addition device 6 is a device that adds a first chemical to the water supply line L1. The first drug addition device 6 is electrically connected to the control section 30.
In this embodiment, the first chemical addition device 6 adds a reducing agent as the first chemical in order to prevent deterioration of the reverse osmosis membrane provided in the reverse osmosis membrane module 17. Examples of the first chemical include reducing agents such as SBS (NaHSO3: sodium bisulfite), sodium sulfite, sodium thiosulfate, and sulfur dioxide gas. In order to simplify the explanation, an example in which the first drug is SBS will be described below, but the present invention is not limited to this.

The second chemical addition device 7 is a device that adds a second chemical to the water supply line L1. The second drug addition device 7 is electrically connected to the control section 30.

In this embodiment, the second drug addition device 7 adds a stabilizer as the second drug in order to prevent deterioration of the reverse osmosis membrane provided in the reverse osmosis membrane module 17. By adding the stabilizer, for example, the hypochlorous acid contained in the feed water W11 becomes stabilized hypochlorous acid. In the reverse osmosis membrane module 17, examples of the second drug include stabilizers such as amine compounds, such as sulfamic acid compounds, since deterioration of the reverse osmosis membrane can be effectively suppressed.

Moreover, the stabilizer may further contain a bromine compound. In this case, by generating stabilized hypobromous acid, it is possible to reduce damage to the reverse osmosis membrane provided in the reverse osmosis membrane module 17, compared to when generating stabilized hypochlorous acid. Become.

Furthermore, the stabilizer may include a halogen bonded to a sulfamic acid compound. That is, the stabilizer may contain a component in the form of a stabilized halogen and a surplus of the sulfamic acid compound. This makes it possible to use stabilized halogen salts as disinfectants in addition to stabilized hypochlorous acid and stabilized hypobromous acid.

In order to simplify the explanation, an example in which the second drug is a sulfamic acid compound will be described below, but the present invention is not limited thereto.

The third chemical addition device 8 is a device that adds a third chemical to the water supply line L1. The third drug addition device 8 is electrically connected to the control section 30.

In this embodiment, the third chemical addition device 8 adds a different type of sterilizer as the third chemical in order to prevent deterioration of the reverse osmosis membrane provided in the reverse osmosis membrane module 17. Here, "another kind of disinfectant" refers to a disinfectant different from the disinfectant produced by the reaction between the free chlorine in the water supply W11 and the stabilizer as the second chemical. Examples of the third agent include disinfectants containing isothiazoline and the like as components that are affected by the reducing agent as the first agent.

The fourth chemical addition device 9 is a device that adds a fourth chemical to the water supply line L1. The fourth drug addition device 9 is electrically connected to the control section 30.

In this embodiment, the fourth chemical addition device 9 adds a scale dispersant as the fourth chemical to suppress the formation of scale such as silica and hardness components in the reverse osmosis membrane module 17. Examples of the fourth agent include a chelating agent having a sequestering and dispersing effect on metal ions, and/or a low molecular weight polymer.

The upstream end of the second water supply line L12 is connected to the connection part J1. The downstream end of the second water supply line L12 is connected to the primary inlet port of the reverse osmosis membrane module 17. A pressurizing pump 15 is provided in the second water supply line L12.

The pressure pump 15 is a device that sucks in the water supply W11 and pumps it (discharges it) toward the reverse osmosis membrane module 17. The pressurizing pump 15 is supplied with drive power whose frequency has been converted from an inverter 16 . The pressurizing pump 15 is driven at a rotational speed according to the frequency of the supplied (input) driving power (hereinafter also referred to as "driving frequency").

The inverter 16 is an electric circuit (or a device having such a circuit) that supplies frequency-converted drive power to the pressurizing pump 15. Inverter 16 is electrically connected to control section 30 . A command signal is input to the inverter 16 from the control section 30 . The inverter 16 outputs driving power at a driving frequency corresponding to the command signal (current value signal or voltage value signal) input by the control unit 30 to the pressurizing pump 15.

The water supply W12 is supplied to the reverse osmosis membrane module 17 via the pressure pump 15. Moreover, the water supply W12 consists of the water supply W11 and the circulating water W40 (described later).

The reverse osmosis membrane module 17 is equipment that separates the feed water W12 into permeated water W20 and concentrated water W30. Specifically, the reverse osmosis membrane module 17 is a device that performs membrane separation treatment on the feed water W12 discharged from the pressure pump 15 into permeated water W20 from which dissolved salts have been removed and concentrated water W30 from which dissolved salts have been concentrated. It is. The reverse osmosis membrane module 17 includes a single or multiple reverse osmosis membrane elements (not shown). The reverse osmosis membrane module 17 performs membrane separation processing on the feed water W12 using these reverse osmosis membrane elements to produce permeated water W20 and concentrated water W30.

The permeated water line L2 is a line that sends out the permeated water W20 separated by the reverse osmosis membrane module 17. The upstream end of the permeated water line L2 is connected to the secondary port of the reverse osmosis membrane module 17. The downstream end of the permeated water line L2 is connected to a storage tank (not shown).

The concentrated water line L3 is a line through which the concentrated water W30 separated by the reverse osmosis membrane module 17 flows. The upstream end of the concentrated water line L3 is connected to the secondary port of the reverse osmosis membrane module 17. Further, the downstream side of the concentrated water line L3 is branched into a circulating water line L4 and a concentrated drainage line L5 at a connecting portion J2.

The circulating water line L4 is connected to the concentrated water line L3, and is a line that returns concentrated water (circulating water W40) as water supply to the water supply line L1. In the present embodiment, the circulating water line L4 is a line that returns (circulates) the concentrated water W30 flowing through the concentrated water line L3 to the upstream side of the pressurizing pump 15 in the water supply line L1 as circulating water W40. The upstream end of the circulating water line L4 is connected to the concentrated water line L3 at a connection J2. Further, the downstream end of the circulating water line L4 is connected to the water supply line L1 at a connecting portion J1. A constant flow valve 18 is provided in the circulating water line L4.

The constant flow valve 18 is a device that adjusts the flow rate of the circulating water W40 flowing through the circulating water line L4 so as to maintain it at a predetermined constant flow value. The "constant flow value" held in the constant flow valve 18 is a concept that has a range of constant flow values, and is not limited to only the target flow value in the constant flow valve. For example, the constant flow valve may have an adjustment error of about ±10% with respect to the target flow value in consideration of the characteristics of the constant flow mechanism (for example, temperature characteristics due to material and structure). The constant flow valve 18 maintains a constant flow rate value without requiring auxiliary power or external operation, and includes, for example, a valve called a water governor. Note that the constant flow valve 18 may be operated by auxiliary power or external operation to maintain a constant flow value.

The concentrated wastewater line L5 is connected to the concentrated water line L3, and is a line that discharges concentrated water as concentrated wastewater W50 to the outside of the system. In this embodiment, the concentrated water line L5 is connected to the concentrated water line L3 at the connection part J2, and discharges the concentrated water W30 separated by the reverse osmosis membrane module 17 to the outside of the apparatus (outside the system) as concentrated water W50. This is the line to do. A proportional control drainage valve 19 is provided in the concentrated drainage line L5.

The proportional control drain valve 19 is a valve that adjusts the flow rate of the concentrated waste water W50 discharged from the concentrated waste water line L5 to the outside of the apparatus. The proportional control drain valve 19 is electrically connected to the control section 30. The valve opening degree of the proportional control drain valve 19 is controlled by a drive signal transmitted from the control section 30. By transmitting a current value signal (for example, 4 to 20 mA) from the control unit 30 to the proportional control drain valve 19 and controlling the valve opening degree, the drain flow rate of the concentrated waste water W50 can be adjusted.

The control unit 30 is configured by a microprocessor (not shown) including a CPU and memory. In the control unit 30, the CPU of the microprocessor executes various controls related to the water treatment system 1 according to a predetermined program read from the memory. Some of the functions of the control unit 30 will be explained below.

FIG. 2 is a functional block diagram of the control section 30. The control unit 30 includes a reducing agent injection control unit 301 , a stabilizing agent injection control unit 302 , a different germicide injection control unit 303 , and a dispersant injection control unit 304 .

The reducing agent injection control unit 301 controls the addition of the reducing agent to the water supply W11 by the first chemical addition device 6 so that a predetermined concentration of chlorine remains in the water supply W11 based on the measured value by the residual chlorine concentration measuring device 5. Control drug dosing.

The stabilizer injection control unit 302 controls the injection of the stabilizer into the water supply W11 by the second chemical addition device 7 so that no chlorine remains in the water supply W11.

The other type of fungicide injection control unit 303 controls the injection of the other type of fungicide into the water supply W11 by the third chemical addition device 8.

The dispersant injection control unit 304 controls the injection of the scale dispersant into the water supply W11 by the fourth chemical addition device 9.

[1.2 Operation of the first embodiment]
The operation of the water treatment system 1 according to the first embodiment will be described below.
When the water supply W11 is supplied from the water source 2 to the first water supply line L11, the residual chlorine concentration measuring device 5 first measures the residual chlorine concentration in the water supply W11.

Next, a reducing agent as a first chemical is added to the water supply W11 from the first chemical addition device 6 under the control of the reducing agent injection control unit 301. At this time, the reducing agent injection control unit 301 controls the reducing agent injection so that a predetermined concentration of chlorine remains in the water supply W11 based on the residual chlorine concentration measured by the residual chlorine concentration measuring device 5. Control notes. Thereby, in the water supply line L1, the reducing agent added by the first chemical addition device 6 reacts with the entire amount of residual chlorine and is oxidized. Therefore, the water supply W12 can be supplied to the reverse osmosis membrane module 17 without any reducing agent remaining.

Next, a stabilizer as a second chemical is added to the water supply W11 from the second chemical addition device 7 under the control of the stabilizer chemical injection control unit 302. At this time, the stabilizer injection control unit 302 controls the injection of the stabilizer into the water supply W11 by the second chemical addition device 7 so that no chlorine remains in the water supply W11. As a result, no chlorine remains in the water supply W11 after the stabilizing agent is poured, so that deterioration of the reverse osmosis membrane provided in the reverse osmosis membrane module 17 can be suppressed.

Next, a different type of fungicide as a third chemical is added to the water supply W11 from the third chemical addition device 8 under the control of the other type of fungicide injection control unit 303. As a result, in addition to the disinfectant produced by the reaction between free chlorine and the stabilizer, other disinfectants are also used to prevent biofilm formation on the reverse osmosis membrane surface of the reverse osmosis membrane module 17. Adhesion can be further suppressed.

Next, a scale dispersant as a fourth chemical is added to the water supply W11 from the fourth chemical addition device 9 under the control of the dispersant chemical injection control unit 304. Thereby, the formation of scales such as silica and hardness components in the reverse osmosis membrane module 17 can be suppressed.

At the connection part J1, the water supply W11 flowing through the first water supply line L11 and the circulating water W40 flowing through the circulating water line L4 join together and flow into the second water supply line L12 as water supply W12.

The feed water W12 is pumped (discharged) toward the reverse osmosis membrane module 17 by a pressurizing pump 15 to which frequency-converted driving power is supplied from the inverter 16.

The feed water W12 that is force-fed (discharged) toward the reverse osmosis membrane module 17 is subjected to membrane separation treatment in the reverse osmosis membrane module 17 into permeated water W20 from which dissolved salts have been removed and concentrated water W30 from which dissolved salts have been concentrated. be done.

The permeated water W20 subjected to the membrane separation process in the reverse osmosis membrane module 17 is sent out through the permeated water line L2 connected to the secondary port of the reverse osmosis membrane module 17.

On the other hand, the concentrated water W30 subjected to the membrane separation process in the reverse osmosis membrane module 17 flows into the concentrated water line L3 connected to the secondary port of the reverse osmosis membrane module 17.

Concentrated water W30 that has flowed into concentrated water line L3 is separated at connection J2 into circulating water W40 that flows through circulating water line L4 and concentrated waste water W50 that flows through concentrated waste water line L5.

The flow rate of the circulating water W40 that has flowed into the circulating water line L4 is maintained at a predetermined constant flow rate value by the constant flow valve 18. The circulating water W40 that has passed through the constant flow valve 18 is returned to the connection part J1.

The flow rate of the concentrated waste water W50 flowing into the concentrated waste water line L5 is adjusted by the proportional control drain valve 19. The concentrated waste water W50 that has passed through the proportional control drain valve 19 is discharged to the outside of the system.

[1.3 Effects of the first embodiment]
According to the water treatment system 1 according to the present embodiment described above, the following effects are achieved, for example.

The water treatment system 1 of the present invention includes a reverse osmosis membrane module 17 that separates filtered feed water W12 into permeated water W20 and concentrated water W30, and a water supply line L1 that supplies feed water W11 and W12 to the reverse osmosis membrane module 17. , a permeated water line L2 that sends out the permeated water W20 separated by the reverse osmosis membrane module 17, a concentrated water line L3 that sends out the concentrated water W30 separated by the reverse osmosis membrane module 17, and a part of the concentrated water W30. or a concentrated wastewater line L5 that discharges the entire concentrated wastewater W50 to the outside of the system, a residual chlorine concentration measuring device 5 that measures the residual chlorine concentration of the water supply W11, and a first chemical addition device that injects a reducing agent into the water supply W11. 6, a second chemical addition device 7 that injects a stabilizer into the water supply W11, and a reducing agent dosing device that controls the dosing of the reducing agent by the first chemical addition device 6 so that a predetermined concentration of chlorine remains. A control unit 301 is provided.

This caused the reducing agent injection control unit 301 to control the reducing agent injection so that a predetermined concentration of chlorine remained in the water supply line L1. Therefore, the water supply W12 can be supplied to the reverse osmosis membrane module 17 without any reducing agent remaining in the water supply line L1. In addition, since the residual chlorine and the stabilizer can be reacted to generate a reactant (stabilized hypochlorous acid) that has a bactericidal effect, it is possible to suppress biofilm inside the reverse osmosis membrane module 17. Become. Particularly, conventionally, there has been a problem that an excessive amount of the reducing agent passes through the reverse osmosis membrane provided in the reverse osmosis membrane module 17 and deteriorates the purity of the treated water. In addition, when SBS as a reducing agent reacts with chlorine, sulfate ions are generated, but since SBS is added before the reverse osmosis membrane module 17, sulfate ions are generated after chlorine is removed and before the reverse osmosis membrane. However, there was a problem in that bacteria that used sulfate ions as a nutritional source were generated. It is possible to suppress the occurrence of such bacteria by preventing the reducing agent from remaining in the water supply line L1 and by generating the above-mentioned reactants through the reaction between the unreacted free chlorine and the stabilizer. . Furthermore, since no surplus reducing agent is generated, it is possible to prevent the inside of the reverse osmosis membrane module 17 from being filled with the reducing agent and creating a reducing atmosphere.

In addition, the water treatment system 1 further includes a third chemical addition device 8 that injects a different type of disinfectant into the water supply W11.

Thereby, by using other types of disinfectants in addition to the above-mentioned reactants (microbicides), it becomes possible to further suppress biofilm adhesion to the reverse osmosis membrane surface.

Moreover, the water treatment system 1 further includes a stabilizer chemical injection control unit 302 that controls the chemical injection of the stabilizer by the second chemical addition device 7 so that chlorine does not remain in the water supply W11.

As a result, no chlorine remains in the water supply W11 after the stabilizing agent is injected, making it possible to suppress deterioration of the reverse osmosis membrane provided in the reverse osmosis membrane module 17.

Furthermore, in the water treatment system 1, the stabilizer includes a sulfamic acid compound.

This makes it possible to suppress biofilm within the reverse osmosis membrane module 17 by producing stabilized hypochlorous acid.

Moreover, in the water treatment system 1, the stabilizer further contains a bromine compound.

Thereby, by producing stabilized hypobromous acid, it is possible to reduce damage to the reverse osmosis membrane compared to the case where stabilized hypochlorous acid is produced.

Furthermore, in the water treatment system 1, the stabilizer further includes a halogen bonded to a sulfamic acid compound.

This makes it possible to use stabilized halogen salts as disinfectants in addition to stabilized hypochlorous acid and stabilized hypobromous acid.

The water treatment system 1 further includes a fourth chemical addition device 9 that injects a scale dispersant into the water supply.

This makes it possible to suppress the production of scales such as silica and hardness components in addition to biofilms.

[2 Second embodiment]
[2.1 Overall configuration]
Hereinafter, a water treatment system 1A according to a second embodiment of the present invention will be described with reference to the drawings. In addition, below, for the sake of simplification of explanation, among the components included in the water treatment system 1A according to the second embodiment, the same components as those included in the water treatment system 1 according to the first embodiment will be referred to. The same reference numerals are used, and the differences between the water treatment system 1A and the water treatment system 1 will be mainly explained.

FIG. 3 is an overall configuration diagram of the water treatment system 1A of the present invention. The water treatment system 1A differs from the water treatment system 1 in that it does not include the third chemical addition device 8 but includes a fifth chemical addition device 10 instead.

The fifth chemical addition device 10 is a device that adds a fifth chemical to the water supply line L1. The fifth drug addition device 10 is electrically connected to the control section 30.
In this embodiment, the fifth chemical addition device 10 adjusts the chlorine concentration in the water supply W11 by adding an oxidizing agent as the fifth chemical in order to suppress biofilm precipitation in the reverse osmosis membrane module 17. . In particular, in this embodiment, when the residual chlorine concentration in the water supply W11 is less than a predetermined value, the residual chlorine concentration is once increased to a predetermined concentration, and the free chlorine of the predetermined amount or more is a reaction product with the stabilizer. A fifth agent is added to produce stabilized hypochlorous acid.

In the reverse osmosis membrane module 17, an example of the fifth agent is a chlorine-based oxidizing agent such as sodium hypochlorite because it can effectively suppress the attachment of biofilm to the surface of the reverse osmosis membrane. . In order to simplify the explanation, an example in which the fifth agent is sodium hypochlorite will be described below, but the present invention is not limited to this. As other chlorine-based oxidizing agents, for example, liquefied chlorine, bleaching powder, chlorinated isocyanuric acid, etc. may be used.

FIG. 4 is a functional block diagram of the control unit 30A. The control unit 30A includes a reducing agent injection control unit 301A, a stabilizing agent injection control unit 302A, a dispersant injection control unit 304, and an oxidizing agent injection control unit 305.

The reducing agent injection control unit 301A injects the reducing agent with the first chemical addition device 6 during normal operation in the water treatment system 1A, and injects the reducing agent with the first chemical addition device 6 during sterilization processing in the water treatment system 1A. The first drug addition device 6 is controlled to stop the drug injection.

The stabilizer chemical injection control unit 302A stops the stabilizer chemical injection by the second chemical addition device 7 during normal operation in the water treatment system 1A, and stops the stabilizer chemical injection by the second chemical addition device 7 during sterilization processing in the water treatment system 1A. Inject the stabilizer according to step 7.

In the water treatment system 1A, the reducing agent injection control unit 301A and the stabilizing agent injection control unit 302A inject the reducing agent during normal operation, while stopping the stabilizing agent injection. On the other hand, during sterilization, while the injection of the reducing agent is stopped, the stabilizing agent is injected.

During sterilization, if the residual chlorine concentration measured by the residual chlorine concentration measuring device 5 is less than a predetermined value, the oxidizing agent injection control unit 305 injects a chlorine-based oxidizing agent so that the residual chlorine concentration reaches a predetermined value. If the value exceeds the value, the fifth chemical addition device 10 is controlled to reduce the amount of chlorine-based oxidizing agent or to stop the chemical injection.

As a result, if the residual chlorine concentration is too low during sterilization treatment, by increasing the residual chlorine concentration to a predetermined concentration, the reaction product (stabilized hypochlorous : Bactericidal agent) can be produced and the bactericidal effect can be ensured. Moreover, when the residual chlorine concentration is high, addition of excessive chlorine-based oxidant can be prevented by reducing the amount of chlorine-based oxidant or stopping the injection of the chlorine-based oxidant.

[2.2 Operation of second embodiment]
Hereinafter, the operation of the water treatment system 1A according to the second embodiment will be explained separately during normal operation and during sterilization processing.

[2.2.1 During normal operation]
In the configuration shown in FIG. 3, the fifth chemical addition device 10 that adds an oxidizing agent as the fifth chemical is installed at the most upstream side of the first water supply line L11. Device 10 does not function.

When the water supply W11 is supplied from the water source 2 to the first water supply line L11, the residual chlorine concentration measuring device 5 first measures the residual chlorine concentration in the water supply W11.

Next, a reducing agent as a first chemical is added to the water supply W11 from the first chemical addition device 6 under the control of the reducing agent injection control unit 301A.

Next, the water supply W11 passes through an addition point by the second chemical addition device 7 that adds a stabilizer as a second chemical. Since then, the addition of a stabilizer as a second drug has been stopped. By controlling the reducing agent injection control section 301A and the stabilizer injection control section 302A, the influence of free chlorine on the reverse osmosis membrane module 17 can be suppressed by causing free chlorine to react with the reducing agent during normal operation.

Next, a scale dispersant as a fourth chemical is added to the water supply W11 from the fourth chemical addition device 9 under the control of the dispersant chemical injection control unit 304. Thereby, the formation of scales such as silica and hardness components in the reverse osmosis membrane module 17 can be suppressed.

At the connection part J1, the water supply W11 flowing through the first water supply line L11 and the circulating water W40 flowing through the circulating water line L4 join together and flow into the second water supply line L12 as water supply W12.

The feed water W12 is pumped (discharged) toward the reverse osmosis membrane module 17 by a pressurizing pump 15 to which frequency-converted driving power is supplied from the inverter 16.

The feed water W12 that is force-fed (discharged) toward the reverse osmosis membrane module 17 is subjected to membrane separation treatment in the reverse osmosis membrane module 17 into permeated water W20 from which dissolved salts have been removed and concentrated water W30 from which dissolved salts have been concentrated. be done.

The permeated water W20 subjected to the membrane separation process in the reverse osmosis membrane module 17 is sent out through the permeated water line L2 connected to the secondary port of the reverse osmosis membrane module 17.

On the other hand, the concentrated water W30 subjected to the membrane separation process in the reverse osmosis membrane module 17 flows into the concentrated water line L3 connected to the secondary port of the reverse osmosis membrane module 17.

Concentrated water W30 that has flowed into concentrated water line L3 is separated at connection J2 into circulating water W40 that flows through circulating water line L4 and concentrated waste water W50 that flows through concentrated waste water line L5.

The flow rate of the circulating water W40 that has flowed into the circulating water line L4 is maintained at a predetermined constant flow rate value by the constant flow valve 18. The circulating water W40 that has passed through the constant flow valve 18 is returned to the connection part J1.

The flow rate of the concentrated waste water W50 flowing into the concentrated waste water line L5 is adjusted by the proportional control drain valve 19. The concentrated waste water W50 that has passed through the proportional control drain valve 19 is discharged to the outside of the system.

[2.2.2 During sterilization treatment]
In the water treatment system 1A, sterilization of the reverse osmosis membrane module 17 is performed at a predetermined timing. Note that the sterilization process may be performed periodically, or may be performed when the reverse osmosis membrane module 17 tends to be clogged.

When the water supply W11 is supplied from the water source 2 to the first water supply line L11, if the residual chlorine concentration measured by the residual chlorine concentration measuring device 5 described below is less than a predetermined value, first, the water supply W11 is Under the control of the oxidizing agent injection control unit 305, the oxidizing agent as the fifth chemical is added from the fifth chemical adding device 10. Thereby, the residual chlorine concentration in the water supply W11 increases to a predetermined concentration.

Next, the water supply W11 passes through an addition point by the first chemical addition device 7 that adds a reducing agent as a first chemical, but under the control of the reducing agent injection control unit 301A, Addition of the reducing agent as the first chemical has been stopped.

Next, a stabilizer as a second chemical is added to the water supply W11 from the second chemical addition device 7 under the control of the stabilizer chemical injection control unit 302A. Under the control of the reducing agent injection control unit 301A and the stabilizer injection control unit 302A, during sterilization treatment, free chlorine and the stabilizer are reacted to form a reactant (stabilized hypochlorous acid) with sterilization effect. can be generated, making it possible to suppress biofilm within the reverse osmosis membrane module 17. In addition, by intermittently supplying the above-mentioned reactant (bactericide) to the reverse osmosis membrane provided in the reverse osmosis membrane module 17, it is possible to suppress the adhesion of biofilm to the membrane surface of the reverse osmosis membrane, and to suppress the adhesion of biofilm to the membrane surface of the reverse osmosis membrane. It becomes possible to aim at peeling off.

Next, a scale dispersant as a fourth chemical is added to the water supply W11 from the fourth chemical addition device 9 under the control of the dispersant chemical injection control unit 304. Thereby, the formation of scales such as silica and hardness components in the reverse osmosis membrane module 17 can be suppressed.

At the connection part J1, the water supply W11 flowing through the first water supply line L11 and the circulating water W40 flowing through the circulating water line L4 join together and flow into the second water supply line L12 as water supply W12.

The feed water W12 is pumped (discharged) toward the reverse osmosis membrane module 17 by a pressurizing pump 15 to which frequency-converted driving power is supplied from the inverter 16.

The feed water W12 that is force-fed (discharged) toward the reverse osmosis membrane module 17 is subjected to membrane separation treatment in the reverse osmosis membrane module 17 into permeated water W20 from which dissolved salts have been removed and concentrated water W30 from which dissolved salts have been concentrated. be done.

The permeated water W20 subjected to the membrane separation process in the reverse osmosis membrane module 17 is sent out through the permeated water line L2 connected to the secondary port of the reverse osmosis membrane module 17.

On the other hand, the concentrated water W30 subjected to the membrane separation process in the reverse osmosis membrane module 17 flows into the concentrated water line L3 connected to the secondary port of the reverse osmosis membrane module 17.

Concentrated water W30 that has flowed into concentrated water line L3 is separated at connection J2 into circulating water W40 that flows through circulating water line L4 and concentrated waste water W50 that flows through concentrated waste water line L5.

The flow rate of the circulating water W40 that has flowed into the circulating water line L4 is maintained at a predetermined constant flow rate value by the constant flow valve 18. The circulating water W40 that has passed through the constant flow valve 18 is returned to the connection part J1.

The flow rate of the concentrated waste water W50 flowing into the concentrated waste water line L5 is adjusted by the proportional control drain valve 19. The concentrated waste water W50 that has passed through the proportional control drain valve 19 is discharged to the outside of the system.

[2.3 Effects of the second embodiment]
According to the water treatment system 1A according to the present embodiment described above, the following effects are achieved, for example.

The water treatment system 1A of the present invention includes a reverse osmosis membrane module 17 that separates filtered feed water W12 into permeated water W20 and concentrated water W30, and a water supply line L1 that supplies feed water W11 and W12 to the reverse osmosis membrane module 17. , a permeated water line L2 that sends out the permeated water W20 separated by the reverse osmosis membrane module 17, a concentrated water line L3 that sends out the concentrated water W30 separated by the reverse osmosis membrane module 17, and a part of the concentrated water W30. or a concentrated wastewater line L5 that discharges the entire concentrated wastewater W50 to the outside of the system, a residual chlorine concentration measuring device 5 that measures the residual chlorine concentration of the water supply W12, and a first chemical addition device that injects a reducing agent into the water supply W11. 6, a second chemical addition device 7 for injecting a stabilizing agent into the water supply W11, and a first chemical addition device 6 for injecting a reducing agent during normal times and stopping the injection of reducing agent during sterilization processing. a reducing agent injection control unit 301A that controls the second chemical addition device 7, and a stabilizer agent that controls the second chemical addition device 7 so as to stop the stabilizing agent injection in normal times and inject the stabilizer during sterilization processing. Note control unit 302A.

This causes the reducing agent injection control unit 301A to control the first chemical addition device 6 to inject the reducing agent in the water supply line L1 during normal times, and to stop the injection of the reducing agent during sterilization processing, thereby stabilizing the water supply line L1. The drug injection control unit 302A controlled the second drug addition device 7 to stop the injection of the stabilizer in the water supply line L1 during normal times, and to inject the stabilizer during the sterilization process. As a result, in the water supply line L1, the influence of free chlorine on the reverse osmosis membrane module 17 can be suppressed by reacting free chlorine with a reducing agent during normal times, and during sterilization treatment, free chlorine is allowed to react with a stabilizing agent. Since a reactant having a bactericidal effect (stabilized hypochlorous acid) can be generated, it is possible to suppress biofilm within the reverse osmosis membrane module 17. In addition, by intermittently supplying the above-mentioned reactant (bactericide) to the reverse osmosis membrane provided in the reverse osmosis membrane module 17, it is possible to suppress the adhesion of biofilm to the membrane surface of the reverse osmosis membrane, and to suppress the adhesion of biofilm to the membrane surface of the reverse osmosis membrane. It becomes possible to aim at peeling off.

The water treatment system 1A also includes a fifth chemical addition device 10 that injects a chlorine-based oxidizing agent into the water supply W11, and a fifth chemical addition device 10 that injects a chlorine-based oxidizing agent into the water supply W11 when the residual chlorine concentration is less than a predetermined value during sterilization treatment. and an oxidizing agent injection control unit 305 that controls the fifth chemical addition device 10 to reduce the amount of chlorine-based oxidizing agent or to stop the chemical injection when the residual chlorine concentration is higher than a predetermined value. It further includes:

As a result, if the residual chlorine concentration is too low during sterilization treatment, by increasing the residual chlorine concentration to a predetermined concentration, the reaction product (stabilized hypochlorous : Bactericidal agent) can be produced and the bactericidal effect can be ensured. Further, when the residual chlorine concentration is high, addition of excessive chlorine-based oxidant can be prevented by reducing the amount of chlorine-based oxidant or stopping the injection.

[3 Third embodiment]
[3.1 Overall configuration]
Hereinafter, a water treatment system 1B according to a third embodiment of the present invention will be described with reference to the drawings. In addition, below, for the sake of simplicity of explanation, among the components included in the water treatment system 1B according to the third embodiment, the same components as those included in the water treatment system 1 according to the first embodiment will be referred to. The same reference numerals are used, and the differences between the water treatment system 1B and the water treatment system 1 will be mainly explained.

FIG. 5 is an overall configuration diagram of the water treatment system 1B of the present invention. Unlike the water treatment system 1, the water treatment system 1B does not include the third chemical addition device 8, but instead includes a reactant concentration measuring device 11.

The reactant concentration measuring device 11 is a device that measures the concentration of a reactant of free chlorine and a stabilizer in the water supply W11 flowing through the water supply line L1. Specifically, when the stabilizer injected by the second chemical addition device 7 does not contain a bromine compound, the reactant concentration measuring device 11 measures the stabilized hypochlorous acid concentration in the water supply W11. . On the other hand, if the stabilizer injected by the second chemical addition device 7 contains a bromine compound, the reactant concentration measuring device 11 measures the stabilized hypobromite concentration in the water supply W11.

The reactant concentration measuring device 11 is connected to the water supply line L1. Further, the reactant concentration measuring device 11 is electrically connected to the control section 30B. The reactant concentration in the feed water W11 measured by the reactant concentration measuring device 11 (hereinafter also referred to as "measured reactant concentration") is transmitted as a detection signal to the control unit 30B. As the reactant concentration measuring device 11, it is possible to use, for example, a colorimetric sensor.

FIG. 6 is a functional block diagram of the control section 30B. The control unit 30B includes a reducing agent injection control unit 301B, a stabilizing agent injection control unit 302, and a dispersant injection control unit 304.

When controlling the reducing agent injection by the first chemical addition device 6 so that a predetermined concentration of chlorine remains, the reducing agent injection control unit 301B is configured to stabilize the free chlorine measured by the reactant concentration measuring device 11. The predetermined concentration is adjusted in stages so that the concentration of the reactant with the curing agent becomes a predetermined value.

[3.2 Operation of third embodiment]
The operation of the water treatment system 1B according to the third embodiment will be described below.
When the water supply W11 is supplied from the water source 2 to the first water supply line L11, the residual chlorine concentration measuring device 5 first measures the residual chlorine concentration in the water supply W11.

Next, a reducing agent as a first chemical is added to the water supply W11 from the first chemical addition device 6 under the control of the reducing agent injection control unit 301B. At this time, the reducing agent injection control unit 301B controls the reducing agent injection so that a predetermined concentration of chlorine remains in the water supply W11, based on the residual chlorine concentration measured by the residual chlorine concentration measuring device 5. Control notes. At this time, the reducing agent injection control unit 301B adjusts the predetermined concentration in stages so that the concentration of the reactant between free chlorine and the stabilizer measured by the reactant concentration measuring device 11 becomes a predetermined value. do. Thereby, by controlling the concentration of the above-mentioned reactant (bactericide), it becomes possible to suppress the adhesion of biofilm to the reverse osmosis membrane surface and to peel off the adhering biofilm. In particular, increasing the concentration of substances that are normally kept at low concentrations to higher levels in stages will be effective in solving the problem of bacterial resistance to disinfectants.

Next, a stabilizer as a second chemical is added to the water supply W11 from the second chemical addition device 7 under the control of the stabilizer chemical injection control unit 302. At this time, the stabilizer injection control unit 302 controls the injection of the stabilizer into the water supply W11 by the second chemical addition device 7 so that no chlorine remains in the water supply W11. As a result, no chlorine remains in the water supply W11 after the stabilizing agent is poured, so that deterioration of the reverse osmosis membrane provided in the reverse osmosis membrane module 17 can be suppressed.

Next, a scale dispersant as a fourth chemical is added to the water supply W11 from the fourth chemical addition device 9 under the control of the dispersant chemical injection control unit 304. Thereby, the formation of scales such as silica and hardness components in the reverse osmosis membrane module 17 can be suppressed.

Further, as described above, the reactant concentration measuring device 11 measures the reactant concentration in the feed water W11. The measured reactant concentration (measured reactant concentration) is transmitted as a detection signal to the control unit 30B, and as described above, the reducing agent injection control unit 301B controls the injection of the reducing agent by the first chemical addition device 6. used for control.

[3.3 Effects of the third embodiment]
According to the water treatment system 1B according to the third embodiment described above, the following effects are achieved, for example.

In the water treatment system 1B, the reducing agent injection control unit 301B adjusts the predetermined concentration in stages so that the concentration of the reactant between free chlorine and the stabilizer in the water supply becomes a predetermined value.

Thereby, by controlling the concentration of the above-mentioned reactant (bactericide), it becomes possible to suppress the adhesion of biofilm to the reverse osmosis membrane surface and measure the detachment of the attached biofilm. In particular, increasing the concentration of substances that are normally kept at low concentrations to higher levels in stages will be effective in solving the problem of bacterial resistance to disinfectants.

[4 Modification]
[4.1 Modification 1]
In the above embodiment, the first chemical addition device 6 added the reducing agent, and the second chemical addition device 7 added the stabilizing agent. That is, in the above embodiment, the reducing agent and the stabilizer were added separately, but the invention is not limited to this. For example, especially in the first embodiment, the reducing agent and the stabilizing agent may be combined into one component. In this case, the ratio of the reducing agent to the stabilizing agent in the chemical may be changed depending on the residual chlorine concentration in the water supply W11 measured by the residual chlorine concentration measuring device 5.

[4.2 Modification 2]
In the embodiment described above, the reducing agent and the stabilizing agent are injected into the water supply W11 supplied from the water source 2, but the present invention is not limited to this. For example, the water treatment systems 1 to 1B may include a filtration device and/or a water softening device, and a reducing agent or a stabilizing agent may be injected into the treated water treated by the filtration device and/or the water softening device. .

[4.3 Modification 3]
In the embodiment described above, it is assumed that the residual chlorine concentration measuring device 5 automatically measures the residual chlorine concentration in the water supply W11, but the present invention is not limited to this. For example, the administrator of the water treatment system 1, 1A, 1B may manually measure the residual chlorine concentration, assume that the residual chlorine concentration is constant, and input the constant value to the control unit 30, 30A, 30B. You can.

[4.4 Modification 4]
In the water treatment system 1 according to the first embodiment, from upstream to downstream of the water supply line L11, the residual chlorine concentration measuring device 5, the first chemical addition device 6, the second chemical addition device 7, and the third chemical addition device 8 and a fourth drug addition device 9 were installed in this order. In the water treatment system 1A according to the second embodiment, from upstream to downstream of the water supply line L11, the fifth chemical addition device 10, the residual chlorine concentration measuring device 5, the first chemical addition device 6, and the second chemical addition device 10, The addition device 7 and the fourth drug addition device 9 were installed in this order. Furthermore, in the water treatment system 1B according to the third embodiment, from the upstream to the downstream of the water supply line L11, the residual chlorine concentration measuring device 5, the first chemical addition device 6, the second chemical addition device 7, and the fourth chemical The addition device 9 and the reactant concentration measuring device 11 were installed in this order. However, these arrangement order and installation locations are just examples, and are not limited to these.

[4.5 Modification 5]
The water treatment system 1 according to the first embodiment, the water treatment system 1A according to the second embodiment, and the water treatment system 1B according to the third embodiment include a circulating water line L4, but are not limited to this. For example, in the case of large-scale equipment, etc., the configuration may not include the circulating water line L4.

1, 1A, 1B Water treatment system 5 Residual chlorine concentration measuring device 6 First chemical addition device (first chemical injection means)
7 Second drug addition device (second drug injection means)
8 Third chemical addition device (third chemical injection means)
9 Fourth drug addition device (fifth drug injection means)
10 Fifth drug addition device (fourth drug injection means)
11 Reactant concentration measuring device 15 Pressure pump 17 Reverse osmosis membrane modules 30, 30A, 30B Control unit (chemical injection control unit)
L1 Water supply line L2 Permeated water line L3 Concentrated water line L4 Circulating water line L5 Concentrated drainage line,
L11 First water supply line L22 Second water supply line

Claims (10)

a reverse osmosis membrane module that separates filtered feed water into permeate water and concentrated water;
a water supply line that supplies water to the reverse osmosis membrane module;
a permeate line that delivers permeate water separated by the reverse osmosis membrane module;
a concentrated water line that delivers concentrated water separated by the reverse osmosis membrane module;
a concentrated drainage line that discharges part or all of the concentrated water to the outside of the system as concentrated wastewater;
a residual chlorine concentration measuring means for measuring the residual chlorine concentration of water supply;
a first chemical injection means for injecting a reducing agent into the water supply;
a second chemical injection means for injecting a stabilizer into the water supply;
A water treatment system comprising: a reducing agent injection control means for controlling the injection of the reducing agent by the first chemical injection means so that a predetermined concentration of chlorine remains. The water according to claim 1, wherein the reducing agent injection control means adjusts the predetermined concentration in stages so that the concentration of the reactant between the residual chlorine and the stabilizer in the water supply becomes a predetermined value. processing system. The water treatment system according to claim 1, further comprising a third chemical injection means for injecting another type of disinfectant into the water supply. The method according to any one of claims 1 to 3, further comprising a stabilizer injection control means for controlling injection of the stabilizer by the second chemical injection means so that chlorine does not remain in the water supply. Water treatment system as described. a reverse osmosis membrane module that separates filtered feed water into permeate water and concentrated water;
a water supply line that supplies water to the reverse osmosis membrane module;
a permeate line that delivers permeate water separated by the reverse osmosis membrane module;
a concentrated water line that delivers concentrated water separated by the reverse osmosis membrane module;
a concentrated drainage line that discharges part or all of the concentrated water to the outside of the system as concentrated wastewater;
a residual chlorine concentration measuring means for measuring the residual chlorine concentration of water supply;
a first chemical injection means for injecting a reducing agent into the water supply;
a second chemical injection means for injecting a stabilizer into the water supply;
Reducing agent injection control means for controlling the first chemical injection means so as to inject the reducing agent during normal times and stop the injection of the reducing agent during sterilization processing;
Stabilizer chemical injection control means that controls the second chemical injection means to stop the chemical injection of the stabilizer during normal times and inject the stabilizer during sterilization processing;
water treatment system. a fourth chemical injection means for chemically injecting a chlorine-based oxidizing agent into the water supply;
During sterilization treatment, when the residual chlorine concentration is less than a predetermined value, the chlorine-based oxidizing agent is injected, and when the residual chlorine concentration is above the predetermined value, the amount of the chlorine-based oxidizing agent is reduced. The water treatment system according to claim 5, further comprising oxidizing agent injection control means for controlling the fourth chemical injection means to stop the chemical injection. The water treatment system according to any one of claims 1 to 6, wherein the stabilizer includes a sulfamic acid compound. The water treatment system according to claim 7, wherein the stabilizer further includes a bromine compound. The water treatment system according to claim 7 or 8, wherein the stabilizer further contains a halogen bonded to the sulfamic acid compound. The water treatment system according to any one of claims 1 to 9, further comprising a fifth chemical injection means for injecting a scale dispersant into the water supply.

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