JP2009189933A - Reduction treatment apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reduction treatment apparatus and method which can satisfactorily perform the reduction treatment even of an oxidizing solution, of which the dissociative state is changed by pH, with a proper amount of injected reducing agent. <P>SOLUTION: The reduction treatment apparatus which performs the reduction treatment of the oxidizing solution stored in a reaction tank 1 by injecting a reducing agent to the solution includes a setting storage part 21 which stores an oxidation-reduction potential reference value determined for each pH value, specifying that a free chlorine concentration in the solution is 0.2 mg/L or less, and a control part 20 which injects the reducing agent and, if necessary, a pH adjusting agent to adjust the pH value of the solution within a predetermined range when a reduction treatment instruction is given, and injects the reducing agent when the oxidation-reduction potential value of the solution after the pH adjustment exceeds the oxidation-reduction potential reference value of the pH value corresponding to the oxidation-reduction potential reference value, and ends the reduction treatment when the oxidation-reduction potential value becomes equal to or less than the oxidation-reduction potential reference value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a reduction treatment apparatus and a reduction treatment method, and more particularly to an oxidizing solution containing an oxidizing agent such as sodium hypochlorite, that is, an oxidizing solution whose dissociation state changes depending on pH. Further, the present invention relates to an improvement of a reduction treatment apparatus and a reduction treatment method for performing a reduction treatment of the solution by injecting a reducing agent.

  Conventionally, as a reduction processing apparatus for performing a reduction treatment of a solution by injecting a reducing agent into an oxidizing solution stored in a reaction tank, pH detection means, oxidation-reduction potential detection means, reducing agent injection means and correction Those provided with means are known.

  The pH detection means is for detecting the pH value of the solution stored in the reaction vessel. The redox potential detecting means is for detecting the redox potential value of the solution stored in the reaction vessel. The reducing agent injection means is for injecting the reducing agent into the oxidizing solution stored in the reaction vessel. The correcting means uses the redox potential value detected through the redox potential detecting means as a reference pH value (pH7) based on the difference between the pH value detected through the pH detecting means and the predetermined reference pH value pH7. This is for correcting to the oxidation-reduction potential value at this time.

  In such a reduction treatment apparatus, the pH value of the oxidizing solution stored in the reaction tank is detected through the pH detection means, and the detected pH value (hereinafter also referred to as the detected pH value) and the reference pH value The oxidation-reduction potential value detected through the correction means based on the difference is corrected to the oxidation-reduction potential value at the reference pH value, and the reducing agent is injected through the reducing agent injection means according to the corrected oxidation-reduction potential value. (See, for example, Patent Document 1).

JP 63-20033 A

  By the way, in the reduction treatment apparatus proposed in Patent Document 1 described above, the oxidation-reduction potential value detected based on the difference between the detected pH value and the reference pH value is corrected to the oxidation-reduction potential value at the reference pH value. However, this is determined on the assumption that the solution to be reduced has a substantially linear displacement relationship between the oxidation-reduction potential value and the pH value. On the other hand, for an oxidizing solution whose dissociation state changes depending on pH, such as an oxidizing solution containing an oxidizing agent such as sodium hypochlorite, the displacement is approximately linear between the redox potential value and the pH value. It is not certain whether or not this relationship is established, and the above-described reduction processing apparatus cannot perform a reduction process satisfactorily with an appropriate amount of reducing agent injected into an oxidizing solution whose dissociation state changes depending on pH. There was a fear.

  In view of the above circumstances, the present invention provides a reduction treatment apparatus and a reduction treatment method that can satisfactorily carry out reduction treatment with an appropriate amount of reducing agent even for an oxidizing solution whose dissociation state changes depending on pH. The purpose is to do.

  In order to achieve the above object, a reduction processing apparatus according to claim 1 of the present invention comprises a reducing agent injection means for injecting a reducing agent into an oxidizing solution, and a pH adjuster for the oxidizing solution. PH reduction agent injection means for injecting, and in the reduction treatment apparatus that performs reduction treatment of the oxidizing solution by injecting the reducing agent by the reducing agent injection means, an oxidizing residual substance that is a target in the solution Storage means for storing a redox potential reference value determined for each pH value that defines that the concentration is in an allowable range, and when a reduction treatment command is given, the reducing agent is supplied through the reducing agent injection means; And adjusting the pH value of the solution to a predetermined range by injecting the pH adjusting agent through the pH adjusting agent injecting means as required, and the redox potential value of the solution after the pH adjustment is stored in the storage means In A control means for injecting a reducing agent through the reducing agent injecting means when the corresponding pH value exceeds a redox potential reference value to be remembered, and ending the reduction process when the reference value is equal to or lower than the oxidation / reduction potential reference value. Features.

  Moreover, the reduction processing apparatus according to claim 2 of the present invention includes a reducing agent injection means for injecting a reducing agent into the oxidizing solution, and the oxidizing solution is injected by the reducing agent injection by the reducing agent injection means. In the reduction treatment apparatus for performing the reduction treatment, there is provided a storage means for storing the oxidation-reduction potential reference value determined for each pH value that stipulates that the target oxidizing residual substance concentration in the solution is within an allowable range. Then, when a reduction treatment command is given, the reducing agent is injected through the reducing agent injection means, and the oxidation-reduction potential value and pH value of the solution detected after the injection of the reducing agent, and the oxidation stored in the storage means When the detected redox potential value is compared with the redox potential reference value of the corresponding pH value, the reducing agent is injected through the reducing agent injection means, while the redox potential value is compared with the redox potential reference value. When equal to or less than position reference value characterized by comprising control means for terminating the reduction process.

  According to a third aspect of the present invention, there is provided the reduction processing apparatus according to the second aspect, wherein the control means is configured such that the detected redox potential value is equal to or lower than the redox potential reference value of the corresponding pH value. Is characterized in that a treatment for neutralizing the solution in the reaction vessel is performed.

  Moreover, the reduction treatment apparatus according to claim 4 of the present invention is the reduction treatment apparatus according to any one of claims 1 to 3, wherein the control means is an oxidizing solution containing an oxidizing agent whose dissociation state changes depending on pH. A reduction process is performed.

  The reduction processing apparatus according to claim 5 of the present invention is characterized in that, in claim 4 described above, the oxidizing agent contained in the oxidizing solution is sodium hypochlorite.

  The reduction treatment apparatus according to a sixth aspect of the present invention is the reduction treatment apparatus according to any one of the first to fifth aspects described above, wherein the control means is used for cleaning a membrane of an apparatus for filtering water to be treated by the membrane. It is characterized in that a reduction treatment is performed on the oxidizing solution which is the waste water of the cleaning liquid.

  Moreover, the reduction treatment method according to claim 7 of the present invention is a reduction treatment method in which the reduction treatment of the oxidizing solution is performed by injecting a reducing agent and, if necessary, a pH adjusting agent into the oxidizing solution. From the adjustment treatment step of injecting a reducing agent into the oxidizing solution and then injecting a pH adjusting agent as necessary to adjust the pH value of the solution to a predetermined range, and from the solution after the adjustment treatment step The detected oxidation-reduction potential value was compared with the oxidation-reduction potential reference value determined for each pH that stipulates that the target oxidizing residual substance concentration in the solution is within the allowable range. A comparison processing step of injecting the reducing agent when the oxidation-reduction potential value exceeds the oxidation-reduction potential reference value of the corresponding pH value, and ending the injection of the reducing agent when the oxidation-reduction potential reference value is lower than the oxidation-reduction potential reference value. With features That.

  Further, the reduction treatment method according to claim 8 of the present invention is a reduction treatment method for reducing the oxidizing solution by injecting a reducing agent into the oxidizing solution, and reducing the oxidizing solution. The injection process step for injecting the agent, the oxidation-reduction potential value and the pH value detected from the solution after the injection process step, and the concentration of the oxidative residual substance in the solution are within the allowable range. Compared with the redox potential reference value determined for each pH value, and when the detected redox potential value exceeds the redox potential reference value of the corresponding pH value, the reducing agent is injected, while the oxidation And a reduction step of terminating injection of the reducing agent when the reduction potential is below the reference value.

  In addition, the reduction treatment method according to claim 9 of the present invention includes the neutralization treatment step of neutralizing the solution in the reaction tank after the injection of the reducing agent in the reduction step according to claim 8 described above. It is characterized by including.

  In addition, the reduction treatment method according to claim 10 of the present invention is the oxidizing solution according to any one of claims 7 to 9, wherein the oxidizing solution contains an oxidizing agent whose dissociation state changes depending on pH. It is characterized by being.

  The reduction treatment method according to claim 11 of the present invention is characterized in that, in claim 10 described above, the oxidizing agent contained in the oxidizing solution is sodium hypochlorite.

  Moreover, the reduction treatment method according to claim 12 of the present invention is the method according to any one of claims 7 to 11, wherein the oxidizing solution is used for cleaning a membrane of an apparatus for filtering water to be treated by the membrane. It is characterized by being drained from the washed liquid.

  According to the reduction treatment apparatus of the present invention, the control means for storing in the storage means the oxidation-reduction potential reference value determined for each pH value that prescribes that the target oxidizing residual substance concentration in the solution is within the allowable range. However, when a reduction treatment command is given, the pH value of the solution is brought to a predetermined range by injecting the reducing agent through the reducing agent injection means and, if necessary, injecting the pH adjusting agent through the pH adjustment agent injection means. When the redox potential value of the solution after adjustment and pH adjustment exceeds the redox potential reference value of the corresponding pH value stored in the storage means, the reducing agent is injected through the reducing agent injection means, while the redox potential reference Since the reduction process is terminated when the value is less than or equal to the value, the target oxidizing residual substance in the solution can be obtained by injecting the reducing agent with the redox potential reference value of the corresponding pH value as a threshold value. It is possible to a degree within an allowable range. Therefore, for example, an oxidizing solution containing an oxidizing agent such as sodium hypochlorite and the like, and an oxidizing solution whose dissociation state changes depending on pH should be reduced with an appropriate reducing agent injection amount. There is an effect that can be.

  Moreover, according to the reduction processing apparatus of the present invention, the storage means stores the oxidation-reduction potential reference value determined for each pH value that defines that the concentration of the target oxidizing residual substance in the solution is within the allowable range. When the control means is given a reduction treatment command, the control means causes the reducing agent to be injected through the reducing agent injection means, and the oxidation-reduction potential value and pH value of the solution detected after the injection of the reducing agent and the redox stored in the storage means. When the detected oxidation-reduction potential value exceeds the oxidation-reduction potential reference value of the corresponding pH value, the reducing agent is injected through the reducing agent-injecting means while the detected oxidation-reduction potential value is less than the oxidation-reduction potential reference value. Since the reduction process is terminated when it becomes, the oxidizing residual substance concentration in the solution is set within an allowable range by injecting the reducing agent using the reference value of the redox potential of the corresponding pH value as a threshold value. Door is possible. Therefore, for example, an oxidizing solution containing an oxidizing agent such as sodium hypochlorite and the like, and an oxidizing solution whose dissociation state changes depending on pH should be reduced with an appropriate reducing agent injection amount. There is an effect that can be.

  According to the reduction treatment method of the present invention, in the adjustment treatment step, after the reducing agent is injected into the oxidizing solution, the pH value of the solution is adjusted to a predetermined range by injecting a pH adjusting agent as necessary. In the comparison process step, the oxidation-reduction potential value detected from the solution after the adjustment treatment step and the oxidation-reduction determined for each pH that stipulates that the concentration of the target oxidizing residual substance in the solution is within an allowable range. When the detected redox potential value exceeds the redox potential reference value of the corresponding pH value, the reducing agent is injected, whereas when the detected redox potential value is lower than the redox potential reference value, Since the injection is terminated, it is possible to bring the target oxidizing residual substance concentration in the solution into an allowable range by injecting the reducing agent using the oxidation-reduction potential reference value of the corresponding pH value as a threshold value. Therefore, for example, an oxidizing solution containing an oxidizing agent such as sodium hypochlorite and the like, and an oxidizing solution whose dissociation state changes depending on pH should be reduced with an appropriate reducing agent injection amount. There is an effect that can be.

  Further, according to the reduction treatment method of the present invention, the reducing agent is injected into the oxidizing solution in the injection treatment step, and the oxidation-reduction potential value and pH value detected from the solution after the injection treatment step in the reduction step. Is compared with the redox potential reference value determined for each pH value that stipulates that the target oxidizing residual substance concentration in the solution is within the allowable range, and the detected redox potential value When the pH value exceeds the oxidation-reduction potential reference value, the reducing agent is injected. When the pH value is lower than the oxidation-reduction potential reference value, the injection of the reducing agent is terminated. Therefore, the oxidation-reduction potential reference value of the corresponding pH value is used as a threshold value. By injecting the reducing agent, it is possible to make the concentration of the oxidative residual substance in the solution within an allowable range. Therefore, for example, an oxidizing solution containing an oxidizing agent such as sodium hypochlorite and the like, and an oxidizing solution whose dissociation state changes depending on pH should be reduced with an appropriate reducing agent injection amount. There is an effect that can be.

  Exemplary embodiments of a reduction processing apparatus and a reduction processing method according to the present invention will be described below in detail with reference to the accompanying drawings. In the following description, the embodiment of the reduction processing apparatus will be mainly described, and the embodiment of the reduction processing method will be described as appropriate during the description of the embodiment of the reduction processing apparatus.

<Embodiment 1>
FIG. 1 is a schematic diagram schematically showing the configuration of the reduction treatment apparatus according to Embodiment 1 of the present invention. The reduction treatment apparatus illustrated here includes a reaction tank 1, a reducing agent container 2, a first pH adjusting agent container 3, a second pH adjusting agent container 4, a stirring mechanism 8, a pH meter 9, and an ORP meter 10. And a control unit (control means) 20.

  The reaction tank 1 stores an oxidizing solution. The oxidizing solution stored in the reaction tank 1 is supplied from a membrane filtration device as shown in FIG.

  Such a membrane filtration apparatus includes a raw water tank 13, a membrane module 14, and a backwash pump 17. The raw water tank 13 is for storing raw water such as river water and lake water. The raw water stored in the raw water tank 13 is sent to the membrane module 14 through a supply line (not shown) by the action of the supply pump 16.

  The membrane module 14 has a membrane in which fine holes are formed, and is filtered by allowing the raw water sent by the supply pump 16 to pass through the membrane. The filtered filtered water is sent to the filtered water tank 15 and stored in the filtered water tank 15.

  The backwash pump 17 reversely removes impurities in the pores of the membrane module 14 and the membrane surface by causing the filtrate water stored in the filtrate water tank 15 to flow backward after the filtration process for a predetermined time in the membrane module 14. It is for performing a washing process. When performing the backwash process by the backwash pump 17, sodium hypochlorite contained in the sodium hypochlorite container 18 is injected into filtered water that flows back by the action of the backwash pump 17 as necessary. Then, the membrane module 14 is passed as a cleaning liquid for sterilization. The cleaning liquid used for the backwashing treatment of the backwashing pump 17 is supplied to the reduction treatment apparatus as washing wastewater after passing through the membrane module 14 and stored in the reaction tank 1 as an oxidizing solution.

  Thus, the oxidizing solution stored in the reaction vessel 1 contains sodium hypochlorite as an oxidizing agent, but the present invention is not limited to this, and various types may be used. For example, a halogen oxide may be used.

Here, the characteristics of the oxidizing solution stored in the reaction tank 1 will be described. This oxidizing solution contains sodium hypochlorite as an oxidizing agent. As shown in FIG. 3, this sodium hypochlorite has a dissociated state depending on pH, that is, chlorine Cl depends on pH. _2. Hypochlorous acid HClO, hypochlorite ion ClO ⁻ and the number of existing forms change. In particular, in the vicinity of pH 5 to pH 10, equilibrium is established by the following formula (1).

Formula (1) HClO⇔ClO ⁻ (hypochlorite ion) + H ⁺ (hydrogen ion)
Hypochlorite (HClO) is hypochlorous acid ion (ClO ^-) high oxidation-reduction potential in comparison with, the pH even Therefore free chlorine concentration is the same, the oxidation-reduction potential is different.

  The reducing agent container 2 contains a reducing agent. Examples of the reducing agent to be accommodated include sodium bisulfite, sodium thiosulfate, sodium ascorbate, and sodium erythorbate, but are not limited thereto. A reducing agent injection pipe 5 is connected to the reducing agent container 2.

  The reducing agent injection pipe 5 has a base end connected to the reducing agent container 2 and a tip facing the upper surface opening of the reaction tank 1, and a reducing agent injection pump 5a is provided in the middle thereof. . Although the details will be described later, the reducing agent injection pump 5a is driven for a predetermined time when a command is given from the control unit 20, and injects the reducing agent into the solution in the reaction tank 1 from the tip of the reducing agent injection pipe 5. Is for. Thus, the reducing agent container 2 constitutes a reducing agent injection means for injecting the reducing agent into the oxidizing solution stored in the reaction tank 1 together with the reducing agent injection pipe 5 and the reducing agent injection pump 5a. ing.

  The 1st pH adjuster container 3 accommodates an alkaline adjuster. Examples of the alkaline adjusting agent to be accommodated include, but are not limited to, caustic soda and sodium hydrogen carbonate. A first pH adjusting agent injection pipe 6 is connected to the first pH adjusting agent container 3.

  The first pH adjusting agent injection pipe 6 has a base end connected to the first pH adjusting agent container 3 and a tip facing the upper surface opening of the reaction tank 1. In the middle of the first pH adjusting agent injection pipe 6 A pump 6a is provided. Although the details will be described later, the first pH adjuster injection pump 6a is driven for a predetermined time when a command is given from the control unit 20, and the alkaline adjuster is supplied from the tip of the first pH adjuster injection pipe 6 to the inside of the reaction tank 1. It is for injecting into the solution.

  The 2nd pH adjuster container 4 accommodates an acid adjuster. Examples of the acid adjusting agent to be accommodated include sulfuric acid, hydrochloric acid, nitric acid and the like, but are not limited thereto. A second pH adjusting agent injection pipe 7 is connected to the second pH adjusting agent container 4.

  The second pH adjusting agent injection pipe 7 has a base end connected to the second pH adjusting agent container 4 and a tip facing the upper surface opening of the reaction tank 1. A pump 7a is provided. As will be described in detail later, the second pH adjuster injection pump 7a is driven for a predetermined time when a command is given from the control unit 20, and the acid adjuster is supplied from the tip of the second pH adjuster injection pipe 7 to the inside of the reaction tank 1. It is for injecting into the solution.

  The stirring mechanism 8 is for stirring the liquid (solution) inside the reaction tank 1. The pH meter 9 detects the pH value of the solution inside the reaction tank 1 and supplies the detected pH value (hereinafter also referred to as a detected pH value) to the control unit 20 as a detection signal. The ORP meter 10 detects the oxidation-reduction potential value of the solution inside the reaction tank 1 and gives the detected oxidation-reduction potential value (hereinafter also referred to as a detected ORP value) to the control unit 20 as a detection signal.

  Reference numeral 11 in FIG. 1 is a drain pipe for discharging the solution inside the reaction tank 1, and reference numeral 12 is a drain valve that allows or regulates discharge of the solution through the drain pipe 11 by opening and closing. is there.

  As shown in FIG. 4, the control unit 20 includes a setting storage unit 21, an input processing unit 22, a pH determination unit 23, a reducing agent injection pump drive processing unit 24, a regulator injection pump drive processing unit 25, a comparison determination unit 26, and An output unit 27 is provided. It should be noted that the components of the control unit 20 shown here are characteristic of the present embodiment, and it goes without saying that the control unit 20 has other components.

  The setting storage unit 21 stores programs and data necessary for the control unit 20 to perform various operations. In the present embodiment, the adjusted pH required for the control unit 20 to perform reduction processing control. This is for setting and storing information and a redox potential reference value. Here, the adjusted pH information is information necessary for adjusting the pH of the oxidizing solution inside the reaction tank 1 to a predetermined range, and in this embodiment, for example, 6.5 to 7 as the range of the drainage reference value. .5 is a predetermined range.

  The oxidation-reduction potential reference value is a value necessary for determining the end of the reduction process when performing the reduction process control, and the free chlorine concentration, which is the target oxidizing residual substance concentration in the solution, is within an allowable range, for example, 0. It is an oxidation-reduction potential value determined for each pH value while prescribing a range of 2 mg / L or less. Specifically, when the pH exceeds 7 (when pH> 7), the oxidation-reduction potential reference value is 630 mV, and when the pH exceeds 6 (more specifically, when 6 <pH ≦ 7), oxidation occurs. The reduction potential reference value is 670 mV. The oxidation-reduction potential reference value set in this way is obtained as follows.

  FIG. 5 shows the experimental relationship between the free chlorine concentration and the redox potential value at pH 6.5 to 7.5. As shown in FIG. 5, in the case of the same free chlorine concentration, it is clear that the redox potential is higher as the pH value is lower. When the free chlorine concentration is 0.2 mg / L or less, the ORP value is 630 mV when the pH value is 7, the ORP value is 670 mV when the pH value is 6, and the ORP value is 570 mV when the pH value is 8. When the pH exceeds 7 (when pH> 7), the redox potential reference value is 630 mV, and the pH exceeds 6 (more in detail). Is 6 <pH ≦ 7), the oxidation-reduction potential reference value is 670 mV.

  The input processing unit 22 inputs various information, and in the present embodiment, in particular, the detection signal (detection pH value) from the pH meter 9 and the detection signal (detection ORP value) from the ORP meter 10. Is input.

  The pH determination unit 23 compares the detected pH value input through the input processing unit 22 with the adjusted pH information stored in the setting storage unit 21 to determine whether the pH of the solution inside the reaction tank 1 is within a predetermined range. It is a judgment.

  The reducing agent injection pump drive processing unit 24 gives a drive command to the reducing agent injection pump 5a. The reducing agent injection pump 5a given this drive command is driven for a predetermined time as described above, whereby a predetermined amount of the reducing agent is injected into the reaction vessel 1.

  The adjustment agent injection pump drive processing unit 25 gives a drive command to the first pH adjustment agent injection pump 6a or the second pH adjustment agent injection pump 7a. The first pH adjusting agent injection pump 6a or the second pH adjusting agent injection pump 7a to which this drive command is given is driven for a predetermined time as described above, whereby a predetermined amount of alkaline adjusting agent or oxidizing adjusting agent is supplied to the reaction tank. 1 is injected inside.

  The comparison determination unit 26 compares the detected ORP value input through the input processing unit 22 with the oxidation-reduction potential reference value stored in the setting storage unit 21, and the pH corresponding to the ORP value of the solution inside the reaction tank 1 corresponds. It is determined whether or not the value is equal to or lower than the oxidation-reduction potential reference value.

  The output unit 27 outputs that the reduction process is completed when it is determined through the comparison determination unit 26 that the ORP value of the solution in the reaction vessel 1 is equal to or less than the oxidation-reduction potential reference value.

  FIG. 6 is a flowchart showing the contents of the reduction process control performed by the control unit. The operation of the reduction processing apparatus will be described by describing the reduction processing control performed by the control unit 20 with reference to FIG.

  When the reduction process command is given (step S101: Yes), the control unit 20 in the reduction process control outputs a drive command to the reducing agent injection pump 5a through the reducing agent injection pump drive processing unit 24 (step S102). ). The reducing agent injection pump 5a to which this drive command is given is driven for a predetermined time, whereby a predetermined amount of the reducing agent is injected into the reaction tank 1.

  Then, after reacting the injected reducing agent and the oxidizing solution stored in the reaction tank 1 for a predetermined time, the control unit 20 detects a detection signal from the pH meter 9 through the input processing unit 22, that is, a detected pH. A value is input (step S103).

  The control unit 20 that has input the detected pH value compares the detected pH value with the adjusted pH information stored in the setting storage unit 21 through the pH determination unit 23, and the detected pH value is in the range of 6.5 to 7.5. If the detected pH value is in the range of 6.5 to 7.5, the detection signal from the ORP meter 10, that is, the detected ORP value is input through the input processing unit 22 (step S22). S104: Yes, Step S105: Yes, Step S106).

  On the other hand, when the detected pH value is less than 6.5 through the pH determination unit 23 (step S104: No), the control unit 20 controls the first pH adjusting agent injection pump 6a through the adjusting agent injection pump drive processing unit 25. The drive command is output (step S107). Thus, the first pH adjusting agent injection pump 6a is driven for a predetermined time, and a predetermined amount of the alkaline adjusting agent is injected into the reaction tank 1. The control unit 20 that has performed the process of step S107 reacts the injected alkaline adjusting agent and the solution stored in the reaction tank 1 for a predetermined time, and then returns the procedure to step S103 to perform the above-described steps. The processes after S103 are repeated.

  Further, when the detected pH value is less than 7.5 through the pH determination unit 23 (step S105: No), the control unit 20 controls the second pH adjusting agent injection pump 7a through the adjusting agent injection pump drive processing unit 25. The drive command is output (step S108). Accordingly, the second pH adjusting agent injection pump 7a is driven for a predetermined time, and a predetermined amount of the acid adjusting agent is injected into the reaction tank 1. The control unit 20 that has performed the process of step S108 reacts the injected acid adjusting agent and the solution stored in the reaction tank 1 for a predetermined time, and then returns the procedure to step S103 to perform the above-described steps. The processes after S103 are repeated.

  The control unit 20 that has performed step S106, that is, the control unit 20 that has input the detected ORP value through the input processing unit 22, transmits the input detected ORP value through the comparison determination unit 26 and the oxidation-reduction potential stored in the setting storage unit 21. By comparing with the reference value, it is determined whether or not the ORP value of the solution inside the reaction vessel 1 is equal to or less than the oxidation-reduction potential reference value of the corresponding pH value. Specifically, when the detected pH value exceeds 7 (step S109: Yes), that is, when the detected pH value is greater than 7 and equal to or less than 7.5, the control unit 20 passes the comparison determination unit 26. Determines whether the detected ORP value is 630 mV (oxidation-reduction potential reference value) or less (step S110).

  When the detected ORP value is 630 mV or less (step S110: Yes), the control unit 20 outputs the fact that the reduction process is completed through the output unit 27 (step S111), and then returns the procedure to this time. The process ends. As a result, the oxidizing solution inside the reaction tank 1 has been reduced to an allowable range in which the free chlorine concentration is 0.2 mg / L or less.

  In step S109, when the detected pH value does not exceed 7 (step S109: No), that is, when the detected pH value is 6.5 or more and 7 or less, the control unit 20 compares the determination unit. 26, it is determined whether or not the detected ORP value is 670 mV (oxidation-reduction potential reference value) or less (step S112).

  When the detected ORP value is 670 mV or less (step S112: Yes), the control unit 20 outputs the fact that the reduction process has been completed through the output unit 27 (step S111), and then returns the procedure to this time. The process ends. The oxidizing solution inside the reaction tank 1 has been reduced to an allowable range in which the free chlorine concentration is 0.2 mg / L or less.

  On the other hand, when the detected ORP value exceeds 630 mV in step S110 (step S110: No), or when the detected ORP value exceeds 670 mV in step S112 (step S112: No), the control unit 20 The procedure is returned to step S102, and the processes after step S102 are repeated. Thereby, it becomes possible to inject | pour a reducing agent in the aspect which maintains the pH value of the solution inside the reaction tank 1 in a predetermined range.

  In this way, after the reduction treatment control is performed and the oxidizing solution in the reaction tank 1 is reduced to a desired state, the reduction treatment apparatus opens the drain valve 12 and the inside of the reaction tank 1 through the drain pipe 11. Drain the solution to the outside.

  As described above, according to the reduction processing apparatus in Embodiment 1 of the present invention, when the reduction processing command is given, the control unit 20 injects a reducing agent and, if necessary, a pH adjusting agent. (The first pH adjusting agent and the second pH adjusting agent) are injected to adjust the pH value of the solution inside the reaction tank 1 to the range of 6.5 to 7.5, and the redox potential value of the solution after pH adjustment is Since the reducing agent is injected when the redox potential reference value of the corresponding pH value stored in the setting storage unit 21 exceeds the redox potential reference value, the reduction process is terminated when the redox potential reference value is lower than the redox potential reference value. By injecting the reducing agent with the reduction potential reference value as a threshold value, the free chlorine concentration in the solution can be set to an allowable range of 0.2 mg / L or less. Therefore, for example, an oxidizing solution containing an oxidizing agent such as sodium hypochlorite and the like, and an oxidizing solution whose dissociation state changes depending on pH should be reduced with an appropriate reducing agent injection amount. Can do.

  Further, according to the reduction treatment apparatus, the reduction treatment as described above is performed, so that a predetermined amount is obtained according to each predetermined pH value (for example, when pH value> 7 and when pH value ≦ 7). It is only necessary to inject a reducing agent, and since there is no need to inject a reducing agent corresponding to the reference pH value as in the prior art, there is no possibility that the amount of reducing agent injected becomes excessively large. Further, there is no need to perform correction processing as in the prior art. Therefore, the reduction treatment can be performed with an appropriate amount of reducing agent injected into the oxidizing solution without increasing the number of treatment steps.

  Furthermore, according to the reduction processing apparatus, the reducing agent is injected to adjust the pH value of the solution inside the reaction tank 1 to the range of the drainage standard value, for example, the range of 6.5 to 7.5. Therefore, the solution after the reduction treatment can be discharged through the drain pipe 11 as it is.

  On the other hand, according to the reduction treatment method in Embodiment 1 of the present invention, a reducing agent is injected into the oxidizing solution inside the reaction tank 1 to adjust the pH value of the solution to a range of 6.5 to 7.5. As a result of comparison between the step of adjusting (adjustment processing step) and the detected ORP value from the solution after the step and the redox potential reference value, the detected ORP value exceeds the redox potential reference value of the corresponding pH value In some cases, a reducing agent is injected, and when the oxidation-reduction potential reference value falls below the reference value, a reduction-agent injection step (comparison processing step) is performed. Therefore, reduction is performed using the oxidation-reduction potential reference value of the corresponding pH value as a threshold value. By injecting the agent, the free chlorine concentration in the solution can be set to an allowable range of 0.2 mg / L or less. Therefore, for example, an oxidizing solution containing an oxidizing agent such as sodium hypochlorite and the like, and an oxidizing solution whose dissociation state changes depending on pH should be reduced with an appropriate reducing agent injection amount. Can do.

  Moreover, according to the said reduction process method, since the said adjustment process process and the said comparison process process are performed, there is no possibility that the injection quantity of a reducing agent may become excessive more than necessary. Further, there is no need to perform correction processing as in the prior art. Therefore, the reduction treatment can be performed with an appropriate amount of reducing agent injected into the oxidizing solution without increasing the number of treatment steps.

  Furthermore, according to the reduction treatment method, the reducing agent is injected to adjust the pH value of the solution inside the reaction tank 1 to the range of the drainage standard value, for example, 6.5 to 7.5. The later solution can be discharged through the drain pipe 11 as it is.

<Embodiment 2>
FIG. 7 is a schematic diagram schematically showing the configuration of the reduction treatment apparatus according to Embodiment 2 of the present invention. In addition, the same code | symbol is attached | subjected to what has the same structure as the reduction | restoration processing apparatus which is Embodiment 1 mentioned above, and the description is abbreviate | omitted. The reduction processing apparatus according to Embodiment 2 of the present invention is configured to include a control unit 30. That is, the reduction processing apparatus in the present embodiment is different from the above-described reduction processing apparatus in the first embodiment in the control unit 30.

  As shown in FIG. 8, the control unit 30 includes a setting storage unit 31, an input processing unit 32, a reducing agent injection pump drive processing unit 33, a regulator injection pump drive processing unit 34, a comparison determination unit 35, and an output unit 36. Configured. It should be noted that the components of the control unit 30 shown here are characteristic of the present embodiment, and it goes without saying that the control unit 30 has other components.

  The setting storage unit 31 stores programs and data necessary for the control unit 30 to perform various operations, and in the present embodiment, the redox necessary for the control unit 30 to perform reduction processing control. A potential reference value is set and stored.

  Here, the oxidation-reduction potential reference value is a value necessary for determining the end of the reduction treatment when performing the reduction treatment control, and the free chlorine concentration that is the target oxidizing residual substance concentration in the solution is within the allowable range. That is, it is an oxidation-reduction potential value determined for each pH value while defining that it is in the range of 0.2 mg / L or less. Specifically, when the pH exceeds 8 (when pH> 8), the oxidation-reduction potential reference value is 570 mV, and when the pH exceeds 7 (more specifically, when 7 <pH ≦ 8), oxidation occurs. When the reduction potential reference value is 630 mV and the pH exceeds 6 (more specifically, when 6 <pH ≦ 7), the oxidation-reduction potential reference value is 670 mV. As shown in FIG. 5, when the free chlorine concentration is 0.2 mg / L or less, when the pH value is 7, the ORP value is 630 mV, the pH value When the pH is 8, the ORP value is 670 mV, and when the pH value is 8, the ORP value is 570 mV. When the free chlorine concentration is such that the reduction process is terminated, the pH exceeds 8 (when pH> 8). When the redox potential reference value is 570 mV and the pH exceeds 7 (7 <pH ≦ 8), the redox potential reference value is 630 mV and the pH exceeds 6 (more specifically, 6 <pH ≦ 7). In this case, the redox potential reference value is 670 mV.

  The input processing unit 32 performs input processing of various types of information. In this embodiment, in particular, the detection signal (detected pH value) from the pH meter 9 and the detection signal (detected ORP value) from the ORP meter 10. Is input.

  The reducing agent injection pump drive processing unit 33 gives a drive command to the reducing agent injection pump 5a. The reducing agent injection pump 5a given this drive command is driven for a predetermined time as described above, whereby a predetermined amount of the reducing agent is injected into the reaction vessel 1.

  The adjustment agent injection pump drive processing unit 34 gives a drive command to the first pH adjustment agent injection pump 6a or the second pH adjustment agent injection pump 7a. The first pH adjusting agent injection pump 6a or the second pH adjusting agent injection pump 7a to which this drive command is given is driven for a predetermined time as described above, whereby a predetermined amount of alkaline adjusting agent or oxidizing adjusting agent is supplied to the reaction tank. 1 is injected inside.

  The comparison determination unit 35 determines whether or not the detected ORP value input through the input processing unit 32 is equal to or less than the oxidation-reduction potential reference value stored in the setting storage unit 31.

  The output unit 36 outputs that the reduction process has been completed when it is determined through the comparison determination unit 35 that the ORP value of the solution in the reaction vessel 1 is equal to or less than the oxidation-reduction potential reference value.

  FIG. 9 is a flowchart showing the contents of the reduction process control performed by the control unit. The operation of the reduction processing device will be described by describing the reduction processing control performed by the control unit 30 with reference to FIG. 9.

  When the reduction process command is given (Step S201: Yes), the control unit 30 in the reduction process control outputs a drive command to the reducing agent injection pump 5a through the reducing agent injection pump drive processing unit 33 (Step S202). ). The reducing agent injection pump 5a to which this drive command is given is driven for a predetermined time, whereby a predetermined amount of the reducing agent is injected into the reaction tank 1.

  Then, after reacting the injected reducing agent with the oxidizing solution stored in the reaction tank 1 for a predetermined time, the control unit 30 detects the detection signal from the pH meter 9 through the input processing unit 32, that is, the detected pH. A value and a detection signal from the ORP meter 10, that is, a detection ORP value are input (step S203).

  The control unit 30 having input the detected pH value and the detected ORP value compares the input detected pH value and detected ORP value with the oxidation-reduction potential reference value stored in the setting storage unit 31 through the comparison determination unit 35, and It is determined whether or not the ORP value of the solution inside the reaction vessel 1 is equal to or less than the oxidation-reduction potential reference value of the corresponding pH value. Specifically, when the detected pH value exceeds 8, the control unit 30 determines whether the detected ORP value is 570 mV or less through the comparison determination unit 35 (step S204: Yes, step S205) When the detected ORP value is 570 mV or less (step S205: Yes), the control unit 30 outputs a message indicating that the reduction process is completed through the output unit 36 (step S206), and then returns the procedure. To end the current process. As a result, the oxidizing solution inside the reaction tank 1 has been reduced to an allowable range in which the free chlorine concentration is 0.2 mg / L or less.

  On the other hand, when the detected ORP value exceeds 570 mV (step S205: No), the control unit 30 returns the procedure to step S202, and repeatedly performs the processing after step S202 described above. Thereby, it becomes possible to inject the reducing agent into the solution inside the reaction tank 1.

  By the way, when the detected pH value input in step S203 is greater than 7 and 8 or less (7 <pH value ≦ 8), it is determined whether or not the detected ORP value is 630 mV or less (step S204: No, step S207: Yes, step S208) When the detected ORP value is 630 mV or less (step S208: Yes), the control unit 30 outputs a message indicating that the reduction process has been completed through the output unit 36 (step S206). ) And then return the procedure to end the current process. As a result, the oxidizing solution inside the reaction tank 1 has been reduced to an allowable range in which the free chlorine concentration is 0.2 mg / L or less.

  When the detected ORP value exceeds 630 mV (step S208: No), the control unit 30 returns the procedure to step S202, and repeatedly performs the processing after step S202 described above. Thereby, it becomes possible to inject the reducing agent into the solution inside the reaction tank 1.

  If the detected pH value input in step S203 is greater than 6 and 7 or less (6 <pH value ≦ 7), it is determined whether or not the detected ORP value is 670 mV or less (step S204: No, Step S207: No, Step S209: Yes, Step S210) When the detected ORP value is 670 mV or less (Step S210: Yes), the control unit 30 outputs the fact that the reduction process has been completed through the output unit 36. (Step S206), and then the procedure is returned to end the current process. As a result, the oxidizing solution inside the reaction tank 1 has been reduced to an allowable range in which the free chlorine concentration is 0.2 mg / L or less.

  When the detected ORP value exceeds 670 mV (step S210: No), the control unit 30 returns the procedure to step S202, and repeatedly performs the processing after step S202 described above. Thereby, it becomes possible to inject the reducing agent into the solution inside the reaction tank 1.

  When the detected pH value input in step S203 is 6 or less (step S204: No, step S207: No, step S209: No), the control unit 30 passes the adjusting agent injection pump drive processing unit 34 to the first pH. A drive command is output to the adjusting agent injection pump 6a (step S211). Thus, the first pH adjusting agent injection pump 6a is driven for a predetermined time, and a predetermined amount of the alkaline adjusting agent is injected into the reaction tank 1. The control unit 30 that has performed the process of step S211 reacts the injected alkaline adjusting agent and the solution stored in the reaction tank 1 for a predetermined time, and then returns the procedure to step S203 to perform the above-described steps. The processes after S203 are repeated. Thereby, it becomes possible to raise the pH value of the solution inside the reaction tank 1.

  In this way, after the reduction treatment control is performed and the oxidizing solution in the reaction tank 1 is reduced to a desired state, the reduction treatment apparatus opens the drain valve 12 and the inside of the reaction tank 1 through the drain pipe 11. Drain the solution to the outside.

  As described above, according to the reduction processing apparatus in Embodiment 2 of the present invention, when the reduction processing command is given, the control unit 30 injects the reducing agent and detects the detected pH value after injecting the reducing agent. The detected ORP value is compared with the oxidation-reduction potential reference value stored in the setting storage unit 31, and when the detected oxidation-reduction potential value exceeds the oxidation-reduction potential reference value of the corresponding pH value, a reducing agent is injected. On the other hand, since the reduction process is terminated when the oxidation-reduction potential reference value is lower than the reference value, the free chlorine concentration in the solution is 0.2 mg by injecting the reducing agent using the oxidation-reduction potential reference value of the corresponding pH value as a threshold value. / L or less is allowed. Therefore, for example, an oxidizing solution containing an oxidizing agent such as sodium hypochlorite and the like, and an oxidizing solution whose dissociation state changes depending on pH should be reduced with an appropriate reducing agent injection amount. Can do.

  In addition, since the reduction treatment apparatus performs the reduction treatment as described above, for each predetermined pH value (for example, when pH value> 8, 7 <pH value ≦ 8, and 6 <pH value). ≦ 7), a predetermined amount of reducing agent may be injected, and it is not necessary to inject a reducing agent corresponding to the reference pH value as in the prior art. There is no fear of becoming. Further, there is no need to perform correction processing as in the prior art. Therefore, the reduction treatment can be performed with an appropriate amount of reducing agent injected into the oxidizing solution without increasing the number of treatment steps.

  On the other hand, according to the reduction treatment method of Embodiment 2 of the present invention, the step of injecting the reducing agent into the oxidizing solution inside the reaction tank 1 (injection treatment step), and the detection ORP of the solution after the step When the detected ORP value exceeds the redox potential reference value of the corresponding pH value as a result of comparison between the value and the detected pH value and the redox potential reference value determined for each pH value, the reducing agent is injected, Since the step of reducing the injection of the reducing agent (reduction step) is performed when the oxidation-reduction potential reference value is lower than the reference value, the reduction agent is injected by using the oxidation-reduction potential reference value of the corresponding pH value as a threshold value. It becomes possible to make the free chlorine concentration within an allowable range of 0.2 mg / L or less. Therefore, for example, an oxidizing solution containing an oxidizing agent such as sodium hypochlorite and the like, and an oxidizing solution whose dissociation state changes depending on pH should be reduced with an appropriate reducing agent injection amount. Can do.

  Moreover, according to the said reduction | restoration processing method, since the said injection | pouring process and the said reduction | restoration process are performed, there is no possibility that the injection quantity of a reducing agent may become excessive too much. Further, there is no need to perform correction processing as in the prior art. Therefore, the reduction treatment can be performed with an appropriate amount of reducing agent injected into the oxidizing solution without increasing the number of treatment steps.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to these embodiments, and various modifications can be made. For example, in the second embodiment, after performing the reduction process control, the control means (control unit 30) causes the detected redox potential value to be equal to or lower than the redox potential reference value of the corresponding pH value. That is, when reduction treatment control is performed, a treatment for neutralizing the solution in the reaction vessel may be appropriately performed.

  As described above, the reduction treatment apparatus and the reduction treatment method according to the present invention are applied to an oxidation solution containing an oxidizing agent such as sodium hypochlorite, that is, an oxidation solution whose dissociation state changes depending on pH. It is useful for reducing the solution by injecting a reducing agent.

It is a schematic diagram which shows typically the structure of the reduction processing apparatus in Embodiment 1 of this invention. It is a schematic diagram which shows typically the structure of the membrane filtration apparatus which supplies an oxidizing solution to the reduction processing apparatus shown in FIG. It is a graph which shows the change of the dissociation state by pH of sodium hypochlorite which is an oxidizing agent. It is a block diagram which shows the structure of the control part shown in FIG. It is the chart which calculated | required experimentally the relationship between the free chlorine concentration in pH 6.5-7.5, and a redox potential value. It is a flowchart which shows the processing content of the reduction process control which a control part implements. It is a schematic diagram which shows typically the structure of the reduction process apparatus in Embodiment 2 of this invention. It is a block diagram which shows the structure of the control part shown in FIG. It is a flowchart which shows the processing content of the reduction process control which a control part implements.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reaction tank 2 Reducing agent container 5 Reducing agent injection piping 5a Reducing agent injection pump 6a 1st pH adjuster injection pump 7a 2nd pH adjuster injection pump 9 pH meter 10 ORP meter 20,30 Control part 21,31 Setting memory | storage part 22, 32 Input processing unit 23 pH determination unit 24, 33 Reducing agent injection pump drive processing unit 25, 34 Adjustment agent injection pump drive processing unit 26, 35 Comparison determination unit 27, 36 Output unit

Claims (12)

Reducing agent injection means for injecting the reducing agent into the oxidizing solution;
PH adjusting agent injection means for injecting the pH adjusting agent into the oxidizing solution,
In a reduction processing apparatus for performing reduction processing of the oxidizing solution by injection of a reducing agent by the reducing agent injection means,
Storage means for storing an oxidation-reduction potential reference value determined for each pH value that defines that the target oxidizing residual substance concentration in the solution is within an allowable range;
When a reduction treatment instruction is given, the pH value of the solution is set within a predetermined range by injecting a reducing agent through the reducing agent injection means and, if necessary, injecting a pH adjusting agent through the pH adjustment agent injection means. When the redox potential value of the solution after pH adjustment exceeds the redox potential reference value of the corresponding pH value stored in the storage means, the reducing agent is injected through the reducing agent injection means, while the oxidation A reduction processing apparatus comprising control means for terminating the reduction processing when the reduction potential is below the reference value. In a reduction processing apparatus comprising a reducing agent injection means for injecting a reducing agent into an oxidizing solution, and performing the reduction treatment of the oxidizing solution by injecting the reducing agent by the reducing agent injection means,
Storage means for storing an oxidation-reduction potential reference value determined for each pH value that defines that the target oxidizing residual substance concentration in the solution is within an allowable range;
When a reduction treatment command is given, the reducing agent is injected through the reducing agent injection means, and the redox potential value and pH value of the solution detected after the reducing agent injection, and the redox potential stored in the storage means When the detected redox potential value exceeds the redox potential reference value of the corresponding pH value by comparing with the reference value, the reducing agent is injected through the reducing agent injecting means, while not more than the redox potential reference value. A reduction processing apparatus comprising control means for terminating the reduction processing when   The said control means performs the process which neutralizes the solution in the said reaction tank, when the detected oxidation-reduction potential value becomes below the oxidation-reduction potential reference value of a corresponding pH value. 2. The reduction treatment apparatus according to 2.   The said control means performs a reduction process to the oxidizing solution containing the oxidizing agent from which a dissociation state changes with pH, The reduction processing apparatus as described in any one of Claims 1-3 characterized by the above-mentioned.   The reduction processing apparatus according to claim 4, wherein the oxidizing agent contained in the oxidizing solution is sodium hypochlorite.   The said control means performs a reduction process to the oxidizing solution which is the waste_water | drain of the washing | cleaning liquid used for washing | cleaning of the film | membrane of the apparatus which filters to-be-processed water with a film | membrane. The reduction processing apparatus according to 1. In the reduction treatment method of carrying out the reduction treatment of the oxidizing solution by injecting a reducing agent and, if necessary, a pH adjusting agent into the oxidizing solution,
After injecting a reducing agent into the oxidizing solution, an adjustment treatment step of injecting a pH adjusting agent as necessary to adjust the pH value of the solution to a predetermined range;
A redox potential value detected from the solution after the adjustment treatment step, and a redox potential reference value determined for each pH that stipulates that the concentration of the target oxidizing residual substance in the solution is within an allowable range; When the detected oxidation-reduction potential value exceeds the oxidation-reduction potential reference value of the corresponding pH value, the reducing agent is injected. When the detected oxidation-reduction potential value falls below the oxidation-reduction potential reference value, the injection of the reducing agent is terminated. And a comparison processing step. In a reduction treatment method for performing a reduction treatment of the oxidizing solution by injecting a reducing agent into the oxidizing solution,
An injection process step of injecting a reducing agent into the oxidizing solution;
Redox potential and pH value detected from the solution after the injection treatment step, and redox determined for each pH value that stipulates that the concentration of the target oxidizing residual substance in the solution is within an allowable range. When the detected redox potential value exceeds the redox potential reference value of the corresponding pH value, the reducing agent is injected, while when the detected redox potential value is lower than the redox potential reference value, the reduction is performed. A reduction process for terminating the injection of the agent.   9. The reduction treatment method according to claim 8, further comprising a neutralization treatment step of neutralizing the solution in the reaction tank after the injection of the reducing agent in the reduction step.   The reduction treatment method according to any one of claims 7 to 9, wherein the oxidizing solution is an oxidizing solution containing an oxidizing agent whose dissociation state changes depending on pH.   The reducing treatment method according to claim 10, wherein the oxidizing agent contained in the oxidizing solution is sodium hypochlorite.   The reduction treatment method according to any one of claims 7 to 11, wherein the oxidizing solution is drainage of a cleaning solution used for cleaning a membrane of an apparatus for filtering water to be treated by a membrane.

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