JP2014100665A - Oxidant processing method and oxidant processing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxidant processing method and an oxidant processing unit in which an oxidant can be performed by reduction treatment while a state of catalytic activity of active carbon is grasped.SOLUTION: An oxidant processing unit 1 includes: an active carbon reaction tank 18 in which water including an oxidant and active carbon are contacted, and the oxidant is performed by reduction treatment; and a gas sensor 30 that detects a generation rate of at least one of carbon monoxide and carbon dioxide generated by contact of the active carbon and the oxidant, and is used.

Description

  The present invention relates to a technique for an oxidizing agent processing method and an oxidizing agent processing apparatus for reducing an oxidizing agent with activated carbon.

  In flue gas desulfurization effluent, it is known that an oxidizing agent such as persulfate is likely to be generated in accordance with changes in operating conditions in the desulfurization apparatus, particularly boiler load. In various industries including the electronics industry, an oxidizing agent such as persulfate is used in the manufacturing process, and thus an oxidizing agent such as persulfate may remain in the waste water. Furthermore, in the purification of groundwater, purification of volatile organic compounds using an oxidizing agent such as persulfate has been put into practical use. In this case, the persulfate that was not involved in the decomposition reaction of the volatile organic compound is groundwater. May remain inside.

  In the case of wastewater treatment, bioinhibition by oxidants such as persulfate occurs in the biological treatment tank at the later stage of the treatment process, so it is necessary to appropriately treat oxidants such as persulfate at the front stage of the biological reaction tank. There is. In the case of groundwater purification, if groundwater in which an oxidizing agent such as persulfate remains is discharged as it is into a river or the like as it is, there is not much influence on the environment, and it is necessary to treat it appropriately as well.

  In such a situation, the present applicant previously relates to a method and an apparatus for treating an oxidizing agent contained in waste water or groundwater with activated carbon, and a processing method for suppressing deterioration of activated carbon by adding a reducing agent and An apparatus has been proposed (see, for example, Patent Document 1).

JP 2005-118626 A

  By the way, since it is difficult to directly and continuously detect the concentration of the oxidizing agent in the water containing the oxidizing agent, the load fluctuation of the water containing the oxidizing agent occurs, and the concentration of the oxidizing agent is higher than expected. If it becomes higher, the catalytic activity of the activated carbon decreases, and the oxidizing agent such as persulfate in water is not sufficiently reduced, and a predetermined amount or more of the oxidizing agent may be discharged from the activated carbon reaction tank. is there. That is, the oxidant may leak.

  Therefore, it is important to grasp the state of catalytic activity of activated carbon. However, as described above, it is very difficult to detect the oxidant concentration directly and continuously. It is also difficult to detect and grasp the state of catalytic activity of activated carbon.

  Then, the objective of this invention is providing the oxidizing agent processing method and oxidizing agent processing apparatus which can carry out the reduction process of an oxidizing agent, grasping | ascertaining the catalytic activity state of activated carbon.

  The present inventors have decomposed activated carbon by increasing the concentration of the oxidizing agent or by reducing the concentration ratio of the reducing agent accompanying the increase in the concentration of the oxidizing agent in the system in which the reducing agent is added. The inventors have found that the catalytic activity of activated carbon decreases as the amount of carbon or carbon dioxide gas generated increases, and have reached the present invention.

  The present embodiment is an oxidant treatment method including a reduction treatment step in which water containing an oxidant and activated carbon are brought into contact to reduce the oxidant, wherein the activated carbon and the oxidant in the reduction treatment step This is a method for detecting the generation amount of at least one of carbon monoxide and carbon dioxide generated by contact with the carbon dioxide.

  Further, in the oxidizing agent treatment method, the reduction treatment step includes a reducing agent addition step of adding a reducing agent to water containing the oxidizing agent, and the reducing agent addition step includes the detected carbon monoxide and the detected It is preferable to control the addition amount or concentration of the reducing agent based on the amount of carbon dioxide generated.

  In the oxidant treatment method, in the reduction treatment step, the supply amount of water containing the oxidant supplied to the activated carbon or the oxidation based on the detected amounts of carbon monoxide and carbon dioxide detected. It is preferable to control the concentration of the oxidizing agent in the water containing the agent.

  In the oxidizing agent treatment method, the oxidizing agent is not particularly limited, but is preferably persulfate or hypochlorite. If the oxidizing agent generates a gas such as oxygen during the reduction process, such as hydrogen peroxide, the amount of carbon monoxide and carbon dioxide generated may not be measured accurately.

  Further, the oxidant treatment apparatus of the present embodiment is produced by bringing the water containing the oxidant into contact with the activated carbon, the activated carbon reaction tank for reducing the oxidant, and the contact between the activated carbon and the oxidant. Detecting means for detecting the amount of generation of at least one of carbon oxide and carbon dioxide.

  Further, in the oxidizer treatment apparatus, a reducing agent adding means for adding a reducing agent to the water containing the oxidizing agent, and the reducing agent adding means based on the detected generation amounts of carbon monoxide and carbon dioxide. And a control means for controlling the addition amount or the concentration of the reducing agent added by the step (1).

  Further, in the oxidant treatment apparatus, the supply means for supplying water containing an oxidant to the activated carbon reaction tank, and the supply means based on the detected generation amounts of carbon monoxide and carbon dioxide. It is preferable to include a control unit that controls a supply amount of water containing the oxidizing agent supplied to the activated carbon reaction tank or a concentration of water containing the oxidizing agent.

  Moreover, in the said oxidizing agent processing apparatus, although the said oxidizing agent does not have a restriction | limiting in particular, It is preferable that they are a persulfate and a hypochlorite. If the oxidizing agent generates a gas such as oxygen during the reduction process, such as hydrogen peroxide, the amount of carbon monoxide and carbon dioxide generated may not be measured accurately.

  Moreover, the said oxidizing agent processing apparatus WHEREIN: It is preferable that the said activated carbon reaction tank is an upward flow type activated carbon reaction tank which lets the water containing the said oxidizing agent flow in an upward flow.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the oxidizing agent processing method and oxidizing agent processing apparatus which can carry out the reduction process of an oxidizing agent, grasping | ascertaining the catalytic activity state of activated carbon.

It is a schematic diagram which shows an example of a structure of the oxidizing agent processing apparatus which concerns on this embodiment. It is a schematic diagram which shows another example of a structure of the oxidizing agent processing apparatus which concerns on this embodiment. It is a schematic diagram which shows another example of a structure of the oxidizing agent processing apparatus which concerns on this embodiment. It is a schematic diagram which shows another example of a structure of the oxidizing agent processing apparatus which concerns on this embodiment. It is a figure which shows the result of the generation amount of the carbon dioxide and carbon monoxide of Examples 5-1-7, and the persulfate density | concentration which remained in the treated water. It is a figure which shows the relationship between the persulfate density | concentration in Example 6, and the amount of carbon monoxide and carbon dioxide generation. It is a figure which shows the relationship between the hypochlorite density | concentration in Example 7, and the amount of carbon monoxide and carbon dioxide generation.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  FIG. 1 is a schematic diagram showing an example of the configuration of the oxidant processing apparatus according to the present embodiment. An oxidant treatment apparatus 1 shown in FIG. 1 includes a raw water inflow line 10, a raw water storage tank 12 as a supply means for supplying water containing an oxidant, a raw water supply line 14, a raw water supply pump 16, and an activated carbon reaction tank 18. A treated water line 20, a treated water storage tank 22, a reducing agent storage tank 24 as a reducing agent addition means, a reducing agent addition pump 26 and a reducing agent addition line 28, a gas sensor 30 as a detection means, and a control means. The control unit 32 is provided.

  As shown in FIG. 1, in this embodiment, one end of the raw water inflow line 10 is connected to the raw water storage tank 12. One end of the raw water supply line 14 is connected to the raw water storage tank 12, and the other end is connected to the bottom of the activated carbon reaction tank 18 via the raw water supply pump 16. One end of the treated water line 20 is connected to the upper side surface of the activated carbon reaction tank 18, and the other end is connected to the treated water storage tank 22. One end of the reducing agent addition line 28 is connected to the reducing agent storage tank 24, and the other end is connected to the raw water supply line 14 via the reducing agent addition pump 26.

  The gas sensor 30 detects the generation amount of at least one of carbon monoxide and carbon dioxide, and is installed in the activated carbon reaction tank 18. The gas sensor 30 is electrically connected to the control unit 32, and detection data detected by the gas sensor 30 is output to the control unit 32. Examples of the gas sensor for carbon monoxide include TGS5042 (manufactured by Figaro Giken), and examples of the gas sensor for carbon dioxide include TGS4160 (manufactured by Figaro Giken).

  The control unit 32 of the present embodiment is electrically connected to the reducing agent addition pump 26, controls the output of the reducing agent addition pump 26 according to the detection data detected by the gas sensor 30, and adds the reducing agent. It is a device having a function of controlling the amount.

  In the present embodiment, the reducing agent storage tank 24, the reducing agent addition pump 26, and the reducing agent addition line 28 are exemplified as the reducing agent addition means. However, the present invention is not limited thereto as long as the reducing agent is supplied to the activated carbon reaction tank 18. Is not to be done. Moreover, in this embodiment, although the raw | natural water storage tank 12, the raw | natural water supply line 14, and the raw | natural water supply pump 16 were illustrated as a supply means, if it is the structure which supplies the water containing an oxidizing agent to the activated carbon reaction tank 18, to this It is not limited.

  Operation | movement of the oxidizing agent processing apparatus 1 which concerns on this embodiment is demonstrated. Hereinafter, water containing an oxidizing agent may be simply referred to as raw water.

  Water containing the oxidant stored in the raw water storage tank 12 from the raw water inflow line 10 is supplied from the raw water supply line 14 to the activated carbon reaction tank 18 by the raw water supply pump 16. In the activated carbon reaction tank 18, the water containing the oxidizing agent comes into contact with the activated carbon in the activated carbon reaction tank 18, and the oxidizing agent is reduced. Water subjected to the reduction treatment of the oxidant passes through the treated water line 20 as treated water and is stored in the treated water storage tank 22.

  Here, when the concentration of the oxidant increases due to fluctuations in the load of water containing the oxidant, for example, when the concentration of the oxidant increases beyond the concentration that can be treated with activated carbon, the activated carbon is decomposed by the oxidant and As the gas generation amount of carbon oxide and carbon dioxide increases, the catalytic activity of the activated carbon rapidly decreases. In such a state, the activated carbon is not sufficiently treated with the activated carbon, and a predetermined amount or more of the oxidizing agent is discharged from the activated carbon reaction tank 18.

  In this embodiment, the gas sensor 30 detects the amount of carbon monoxide and carbon dioxide generated in the activated carbon reaction tank 18 in real time. Therefore, if the detection value of the gas sensor 30 rises, it can be grasped that the amount of carbon monoxide and carbon dioxide generated in the activated carbon reaction tank 18 is increased, and the catalytic activity of the activated carbon is lowered. I can understand that. Therefore, the state of the catalytic activity of the activated carbon is confirmed by the operator or the like confirming the detection value of the gas sensor 30 by visual observation or confirming the history of the detection value data in a graph or a table. Can be grasped in real time.

  Below, the operation | movement of the oxidizing agent processing apparatus 1 which controls the addition amount of a reducing agent according to the generation amount of the carbon monoxide and carbon dioxide detected with the gas sensor 30 is demonstrated.

  Hereinafter, a preset upper limit threshold value is stored in the control unit 32, and when the detection value of the gas sensor 30 exceeds the upper limit threshold value, the reducing agent addition pump 26 is increased to a predetermined output value. It is set to issue a command. In addition, the control unit 32 stores a preset lower limit threshold value, and instructs the reducing agent addition pump 26 to decrease to a predetermined output value when the detection value of the gas sensor 30 falls below the lower limit threshold value. It is desirable to set so that

First, the water containing the oxidizing agent stored in the raw water storage tank 12 from the raw water inflow line 10 is supplied from the raw water supply line 14 to the activated carbon reaction tank 18 by the raw water supply pump 16. Further, the reducing agent in the reducing agent storage tank 24 is supplied from the reducing agent addition line 28 to the activated carbon reaction tank 18 by the reducing agent addition pump 26. In the activated carbon reaction tank 18, when activated carbon is brought into contact with the activated carbon in a state where the oxidizing agent and the reducing agent coexist, the activated carbon can be used as a catalyst to promote the reducing reaction of the oxidizing agent. For example, if the oxidizing agent is persulfate and the reducing agent is hydrogen peroxide, the persulfate and hydrogen peroxide coexist in the presence of activated carbon, and the persulfate can be expressed by the following formulas (1) and (2 ) Proceeds.
2Na ₂ S ₂ O ₈ + 2H ₂ O → 2Na ₂ SO ₄ + 2H ₂ SO ₄ + O ₂ (1)
Na ₂ S ₂ O ₈ + H ₂ O ₂ → Na ₂ SO ₄ + H ₂ SO ₄ + O ₂ (2)

  Since the persulfate and hydrogen peroxide are allowed to coexist in the presence of activated carbon, the persulfate can be rapidly decomposed, so that deterioration of the activated carbon can be suppressed.

In the activated carbon reaction tank 18, hydrogen peroxide is also reduced and decomposed by activated carbon. The reduction reaction is represented by the following formula (3).
2H ₂ O ₂ → 2H ₂ O + O ₂ (3)

  Here, as described above, when the concentration of the oxidizing agent (persulfate) flowing into the activated carbon reaction tank 18 rises to a predetermined concentration or more due to fluctuations in the raw water load, the oxidizing agent decomposes the activated carbon. A large amount of carbon monoxide and carbon dioxide gas is generated. In such a case, in this embodiment, the gas sensor 30 detects the generation amount of carbon monoxide and carbon dioxide in the activated carbon reaction tank 18 in real time (outputs the detection value to the control unit 32). When the upper limit threshold value stored in the control unit 32 is exceeded, the control unit 32 increases the output of the reducing agent addition pump 26 to increase the amount of reducing agent added. By increasing the amount of the reducing agent added, the decomposition of the oxidizing agent is also promoted, so that the reduction in the catalytic activity of the activated carbon is suppressed, and for example, the reduction reaction represented by the above (1) and (2) proceeds stably. Therefore, it is possible to suppress discharge of a predetermined amount or more of the oxidizing agent from the activated carbon reaction tank 18. In addition, when the concentration of the oxidizing agent (persulfate) flowing into the activated carbon reaction tank 18 is lowered to a predetermined concentration or less due to fluctuations in the raw water load, a situation where excessive reducing agent is added to the activated carbon reaction tank 18. Because of this, the processing cost may increase. Even in such a case, in the present embodiment, the gas sensor 30 detects the generation amount of carbon monoxide and carbon dioxide in the activated carbon reaction tank 18 in real time (outputs the detection value to the control unit 32). When the value falls below the lower threshold stored in the control unit 32, the control unit 32 reduces the output of the reducing agent addition pump 26 and decreases the amount of reducing agent added. As a result, it is possible to suppress an unnecessary reducing agent from being added to the activated carbon reaction tank 18, and thus it is possible to suppress an increase in processing cost.

  As another method for controlling the addition amount of the reducing agent, a map or table indicating the relationship between the detected value of the gas sensor 30 and the addition amount of the reducing agent is stored in the control unit 32, and the gas sensor 30 actually detected is stored. The detected value may be applied to a map or the like to determine the addition amount of the reducing agent, and the output of the reducing agent addition pump 26 may be controlled so that the calculated addition amount of the reducing agent is obtained. Further, an electromagnetic valve or the like may be installed in the reducing agent addition line 28, and the amount of reducing agent added may be adjusted by controlling the degree of opening and closing of the electromagnetic valve by the control unit 32 in accordance with the detection value of the gas sensor 30. .

  FIG. 2 is a schematic diagram illustrating another example of the configuration of the oxidizer treatment apparatus according to the present embodiment. 2 includes a reducing agent storage tank 34, a reducing agent addition pump 26, a reducing agent addition line 28, a reducing agent dilution water addition line 36, and a solenoid valve 38 as reducing agent addition means. is there. In the present embodiment, the reducing agent stored in the reducing agent storage tank 34 is concentrated water. One end of the reducing agent dilution water addition line 36 is connected to the reducing agent addition line 28, and the other end is connected to the treated water line 20. A solenoid valve 38 is provided at a connection point between the reducing agent dilution water addition line 36 and the treated water line 20, and is electrically connected to the control unit 32.

  In the present embodiment, for example, normally, the reducing agent addition pump 26 sends the reducing agent concentrated water from the reducing agent storage tank 34 to the reducing agent addition line 28, and the treated water passing through the treated water line 20 is diluted with the reducing agent. The solution is fed from the water addition line 36 to the reducing agent addition line 28 to dilute the reducing agent concentrated water, and is supplied to the activated carbon reaction tank 18. When the detected value of the gas sensor 30 exceeds the upper limit threshold stored in the control unit 32, the opening of the electromagnetic valve 38 is adjusted by the control unit 32, and the treated water flowing through the reducing agent dilution water addition line 36 is adjusted. Limit the flow rate. Thereby, since the diluting effect of reducing agent concentrated water decreases, the concentration of the reducing agent added to the activated carbon reaction tank 18 increases. By increasing the concentration of the reducing agent, the decomposition of the oxidizing agent is also promoted, so that a reduction in the catalytic activity of the activated carbon is suppressed, and for example, the reduction reaction represented by the above (1) and (2) is stably advanced. It becomes possible. When the detected value of the gas sensor 30 falls below the lower limit threshold value stored in the control unit 32, the control unit 32 adjusts the opening of the electromagnetic valve 38, and the treated water flowing through the reducing agent dilution water addition line 36. Increase the flow rate. Thereby, since the dilution effect of reducing agent concentrated water increases, the density | concentration of the reducing agent which flows in into the activated carbon reaction tank 18 can be reduced.

  FIG. 3 is a schematic diagram illustrating another example of the configuration of the oxidizer treatment apparatus according to the present embodiment. In the oxidant processing apparatus 3 shown in FIG. 3, the same components as those in the oxidant processing apparatus 1 shown in FIG. In the oxidizer treatment apparatus 3 shown in FIG. 3, the control unit 32 is electrically connected to the raw water supply pump 16.

  In the oxidant treatment apparatus 3 shown in FIG. 3, the concentration of the oxidant (persulfate) flowing into the activated carbon reaction tank 18 rises to a predetermined concentration or more due to fluctuations in the raw water load, and the detection value of the gas sensor 30 is controlled. When the upper limit threshold stored in the unit 32 is exceeded, the control unit 32 reduces the output of the raw water supply pump 16 to reduce the supply amount of the raw water (water containing the oxidizing agent) flowing into the activated carbon reaction tank 18. Decrease. Thereby, since it can suppress that an excess oxidizing agent flows in into the activated carbon reaction tank 18, the fall of the catalytic activity of activated carbon is suppressed, for example, the reduction reaction represented by said (1), (2) Can be stably advanced. As a result, it is possible to suppress discharge of a predetermined amount or more of the oxidizing agent from the activated carbon reaction tank 18. Further, due to the fluctuation of the raw water load, the concentration of the oxidant (persulfate) flowing into the activated carbon reaction tank 18 decreases to a predetermined concentration or less, and the detection value of the gas sensor 30 falls below the lower limit threshold value stored in the control unit 32. In this case, the control unit 32 increases the output of the raw water supply pump 16 to increase the supply amount of the raw water flowing into the activated carbon reaction tank 18. Thereby, the treatment efficiency of the oxidant can be increased by increasing the supply amount and increasing the load while the oxidant concentration is low.

  FIG. 4 is a schematic diagram illustrating another example of the configuration of the oxidizer treatment apparatus according to the present embodiment. In the oxidizer treatment apparatus 4 shown in FIG. 4, the same components as those in the oxidizer treatment apparatus 1 shown in FIG. In addition to the raw | natural water storage tank 12, the raw | natural water supply line 14, and the raw | natural water supply pump 16, the oxidizing agent processing apparatus 4 shown in FIG. 4 is further provided with the raw | natural water dilution line 40 and the dilution water pump 42. One end of the raw water dilution line 40 is connected to the raw water supply line 14, and the other end is connected to, for example, the treated water storage tank 22 via a dilution water pump 42.

  In the oxidant treatment device 4 shown in FIG. 4, the concentration of the oxidant (persulfate) flowing into the activated carbon reaction tank 18 rises to a predetermined concentration or more due to fluctuations in the raw water load, and the detection value of the gas sensor 30 is controlled. When the upper limit threshold stored in the unit 32 is exceeded, the control unit 32 operates the dilution water pump 42 (or increases the output), and passes the dilution water (treatment) from the treated water storage tank 22 through the raw water dilution line 40. Water) is passed through the raw water supply line 14 to dilute the raw water and reduce the concentration of the oxidant flowing into the activated carbon reaction tank 18. Thereby, since it can suppress that an excess oxidizing agent flows in into the activated carbon reaction tank 18, the fall of the catalytic activity of activated carbon is suppressed, for example, the reduction reaction represented by said (1), (2) Can be stably advanced. As a result, it is possible to suppress discharge of a predetermined amount or more of the oxidizing agent from the activated carbon reaction tank 18. Further, due to the fluctuation of the raw water load, the concentration of the oxidant (persulfate) flowing into the activated carbon reaction tank 18 decreases to a predetermined concentration or less, and the detection value of the gas sensor 30 falls below the lower limit threshold value stored in the control unit 32. In this case, the control unit 32 increases the output of the raw water supply pump 16 to increase the supply amount of the raw water flowing into the activated carbon reaction tank 18. Thereby, the treatment efficiency of the oxidizing agent can be increased while the concentration of the oxidizing agent is low.

  Hereinafter, other conditions in the persulfate reduction treatment will be described.

  Examples of the oxidizing agent to be treated in this embodiment include persulfate and hypochlorous acid. In particular, since persulfate has a high ability to decompose activated carbon among oxidizers, it is useful to use the oxidizer treatment apparatus of this embodiment in order to suppress a decrease in the catalytic activity of activated carbon due to persulfate. is there. Examples of water containing persulfate include waste water discharged from a CMP process in the semiconductor industry. The CMP process is usually called CMP because it is a chemical (= chemical) containing an abrasive and polishing with a grindstone (= mechanical).

  The reducing agent used in the present embodiment is not particularly limited as long as it reduces and decomposes the oxidizing agent to be treated, but when a persulfate is used as the oxidizing agent to be treated. Hydrogen peroxide is preferably used from the viewpoint of safety that the products after decomposition are water and oxygen and reaction efficiency with persulfate. Commercially available hydrogen peroxide may be used, but it is preferable to use, for example, waste water discharged from the semiconductor cleaning process. As represented by (3) above, hydrogen peroxide is reduced by activated carbon, so if wastewater containing hydrogen peroxide is used, hydrogen peroxide is treated together with the treatment of wastewater containing persulfate. The waste water contained can be treated.

  As the activated carbon reaction tank 18 of the present embodiment, an activated carbon tower (fixed bed type or fluidized bed type) filled with activated carbon can be used in addition to a complete mixing type reaction tank such as a batch type reaction tank. Any type of activated carbon such as coal, coconut shell, and charcoal can be used. As the shape of the activated carbon, powder, granule, sphere, pellet, fiber and the like can be used, but when using a complete mixing type reaction tank as the activated carbon reaction tank 18, powder activated carbon having a high reaction rate is used. When using an activated carbon tower (fixed bed type or fluidized bed type), it is desirable to use granular, pelletized or fibrous activated carbon with emphasis on separability and the like.

  The optimum pH of the water in the activated carbon reaction tank 18 is not particularly limited as long as it is not a remarkable acidic region or alkaline region. Treatment with an extremely acidic region or alkaline region accelerates the deterioration of the activated carbon.

  Moreover, it is preferable to employ | adopt the upward flow type reaction tank which allows the activated carbon reaction tank 18 of this embodiment to flow the water containing an oxidizing agent by an upward flow. As described above, even when activated carbon is decomposed by persulfate and carbon monoxide or carbon dioxide gas is generated, water containing an oxidizing agent is passed through the activated carbon reaction tank 18 in an upward flow. This is because, for example, accumulation of the gas in the apparatus can be suppressed.

  The concentration of the oxidizing agent in water is preferably in the range of 10 to 100000 mg / L, more preferably in the range of 50 to 50000 mg / L, from the viewpoint of the actual wastewater situation. Further, the concentration of the reducing agent is preferably in the range of 2 to 20000 mg / L, more preferably in the range of 10 to 10000 mg / L, from the viewpoint of reaction efficiency with the oxidizing agent, and the addition ratio of the reducing agent to the oxidizing agent in water. Is preferably 0.2 or more. When the addition ratio of the reducing agent to the oxidizing agent in water is less than 0.2, activated carbon is decomposed by the oxidizing agent, carbon monoxide and carbon dioxide are remarkably generated, and the catalytic activity of the activated carbon may be reduced.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail more concretely, this invention is not limited to a following example.

Example 1
An activated carbon column was prepared by filling a transparent PVC column (inner diameter 40 mm, height 800 mm) with coconut shell activated carbon as a catalyst to a height of 400 mm, and water containing an oxidizing agent was passed in an upward flow. And created a device for processing. The activated carbon column contains water containing an oxidizing agent prepared by adding pure sodium persulfate to 2000 mg / L with pure water, and hydrogen peroxide as a reducing agent at 400 mg / L (the concentration of hydrogen peroxide relative to sodium persulfate). The addition ratio 0.2) was passed at a superficial velocity of 5 / hr. The amount of carbon dioxide and carbon monoxide generated at the upper part of the activated carbon column and the concentration of persulfate remaining in the treated water were measured.

(Example 2)
A column water flow test under the same conditions as in Example 1 was conducted except that hydrogen peroxide was changed to 600 mg / L (sodium persulfate concentration addition ratio 0.2) with respect to sodium persulfate 3000 mg / L. The amount of carbon dioxide and carbon monoxide generated in the upper part of the activated carbon column and the concentration of persulfate remaining in the treated water were measured.

(Example 3)
A column water flow test under the same conditions as in Example 1 was conducted except that hydrogen peroxide was 4000 mg / L with respect to 20000 mg / L of sodium persulfate (concentration ratio of hydrogen peroxide to sodium persulfate was 0.2). The amount of carbon dioxide and carbon monoxide generated in the upper part of the activated carbon column and the concentration of persulfate remaining in the treated water were measured.

Example 4
Water containing an oxidizing agent prepared by adding pure sodium persulfate to 20000 mg / L and hydrogen peroxide 400 mg / L as a reducing agent (concentration ratio of hydrogen peroxide to sodium persulfate 0.02) Was passed through at a superficial velocity of 5 / hr. The amount of carbon dioxide and carbon monoxide generated at the upper part of the activated carbon column and the concentration of persulfate remaining in the treated water were measured.

  Table 1 summarizes the results of the amounts of carbon dioxide and carbon monoxide generated in Examples 1 to 4 and the concentration of persulfate remaining in the treated water.

  As can be seen from Table 1, in Examples 1 to 3 where the addition ratio of hydrogen peroxide to persulfate was 0.2, the residual sodium persulfate in the treated water was less than 40 mg / L, and the sodium persulfate was treated well. We were able to. At this time, the amounts of carbon dioxide and carbon monoxide generated in the upper part of the activated carbon column were below a certain level. Therefore, it can be said that the catalytic activity of the activated carbon was not lowered. On the other hand, in Example 4 where the addition ratio of hydrogen peroxide to persulfate is 0.02, as in Example 4, the persulfate treated with activated carbon becomes excessive, and residual persulfate in the treated water. Sodium was higher than in Examples 1-3. And the gas generation amount of the carbon dioxide and carbon monoxide of the upper part of the activated carbon column at this time increased, and it turned out that the catalytic activity of activated carbon fell.

(Example 5-1)
Hydrogen peroxide as an additive was added to sodium persulfate 2000 mg / L at 400 mg / L (concentration ratio of hydrogen peroxide to sodium persulfate 0.2), and water was passed for 1 hour at a superficial velocity of 5 / hr. The amount of carbon dioxide and carbon monoxide generated at the upper part of the activated carbon column and the concentration of persulfate remaining in the treated water were measured.

(Example 5-2)
After the test of Example 5-1 (after passing water for 1 hour), a treatment with a sodium persulfate concentration of 2000 mg / L (hydrogen peroxide concentration addition ratio to sodium persulfate 0.2) was performed for 1 hour. The amount of carbon dioxide and carbon monoxide generated at the upper part of the activated carbon column and the concentration of persulfate remaining in the treated water were measured.

(Example 5-3)
After the test of Example 5-2, a treatment with a sodium persulfate concentration of 20000 mg / L (a concentration addition ratio of hydrogen peroxide to sodium persulfate of 0.02) was performed for 1 hour. The amount of carbon dioxide and carbon monoxide generated at the upper part of the activated carbon column and the concentration of persulfate remaining in the treated water were measured.

(Example 5-4)
Moreover, after the test of Example 5-3, the process which makes a sodium persulfate density | concentration 2000 mg / L (concentration addition ratio of the hydrogen peroxide with respect to sodium persulfate 0.2) was performed for 1 hour. The amount of carbon dioxide and carbon monoxide generated at the upper part of the activated carbon column and the concentration of persulfate remaining in the treated water were measured.

(Example 5-5)
After the test of Example 5-4, a treatment with a sodium persulfate concentration of 2000 mg / L (hydrogen peroxide concentration addition ratio to sodium persulfate 0.2) was performed for 1 hour. The amount of carbon dioxide and carbon monoxide generated at the upper part of the activated carbon column and the concentration of persulfate remaining in the treated water were measured.

(Example 5-6)
After the test of Example 5-5, treatment with a sodium persulfate concentration of 2000 mg / L (hydrogen peroxide concentration addition ratio to sodium persulfate 0.2) was performed for 1 hour. The amount of carbon dioxide and carbon monoxide generated at the upper part of the activated carbon column and the concentration of persulfate remaining in the treated water were measured.

(Example 5-7)
After the test of Example 5-6, a treatment with a sodium persulfate concentration of 2000 mg / L (hydrogen peroxide concentration addition ratio to sodium persulfate 0.2) was performed for 1 hour. The amount of carbon dioxide and carbon monoxide generated at the upper part of the activated carbon column and the concentration of persulfate remaining in the treated water were measured.

  Table 2 and FIG. 5 summarize the results of the amounts of carbon dioxide and carbon monoxide generated in Examples 5-1 to 7 and the concentration of persulfate remaining in the treated water.

  As can be seen from the results of Table 2 and Examples 5-1 to 7 in FIG. 5, when the concentration of persulfate increased, the amount of carbon dioxide and carbon monoxide generated at the top of the activated carbon column also increased. Therefore, for example, if the threshold for the amount of carbon monoxide or carbon dioxide generated is set to 1100 ppm and the amount of hydrogen peroxide added is controlled, the increase in the residual persulfate concentration (result of Example 5-3) is suppressed. In addition, it becomes possible to efficiently reduce and decompose persulfate.

(Example 6)
An activated carbon column was prepared by filling a transparent PVC column (inner diameter 40 mm, height 800 mm) with coconut shell activated carbon as a catalyst to a height of 400 mm, and water containing an oxidizing agent was passed in an upward flow. And created a device for processing. And the water containing the oxidizing agent which adjusted the sodium persulfate with the pure water so that it might be set to 100, 200, 500, 1000 mg / L to this activated carbon column was water-flowed at the superficial velocity of 5 / hr. The amount of carbon dioxide and carbon monoxide generated at the upper part of the activated carbon column at this time was measured and summarized in Table 3 and FIG.

  FIG. 6 is a graph showing the relationship between the persulfate concentration and the amounts of carbon monoxide and carbon dioxide generated in Example 6. As can be seen from FIG. 6 and Table 3, it was found that the amount of carbon monoxide and carbon dioxide generated increased as the persulfate concentration increased. And when the persulfate concentration exceeds 500 mg / L, the generation amounts of carbon monoxide and carbon dioxide are rapidly increased, and the catalytic activity of the activated carbon is expected to decrease. Therefore, when persulfate is treated in a system to which no reducing agent is added, the persulfate concentration is reduced to 500 mg / L or less when it is detected that the generation amount of carbon monoxide and carbon dioxide has rapidly increased. It is desirable to dilute.

(Example 7)
It tested on the conditions similar to Example 6 except having replaced with sodium persulfate and adjusting sodium hypochlorite with the pure water so that it might become 10, 20, 50, 100, and 200 mg / L. At this time, carbon dioxide and carbon monoxide generation amounts at the top of the activated carbon column were measured, and are summarized in Table 4 and FIG.

  FIG. 7 is a graph showing the relationship between hypochlorite concentration and the amount of carbon monoxide and carbon dioxide generated in Example 7. As can be seen from FIG. 7 and Table 4, when the hypochlorite concentration exceeds 100 mg / L, the generation amount of carbon monoxide and carbon dioxide increases rapidly, and the catalytic activity of activated carbon decreases. It is expected that Therefore, when hypochlorite is treated in a system in which no reducing agent is added, when it is detected that the amount of carbon monoxide and carbon dioxide generated suddenly increases, the hypochlorite concentration is 100 mg. It is desirable to dilute below / L.

1-4 Oxidizing agent treatment apparatus, 10 raw water inflow line, 12 raw water storage tank, 14 raw water supply line, 16 raw water supply pump, 18 activated water reaction tank, 20 treated water line, 22 treated water storage tank, 24 reducing agent storage tank, 26 reducing agent addition pump, 28 reducing agent addition line, 30 gas sensor, 32 control unit, 34 reducing agent storage tank, 36 reducing agent dilution water addition line, 38 solenoid valve, 40 raw water dilution line, 42 dilution water pump.

Claims (9)

An oxidizing agent treatment method comprising a reduction treatment step of bringing water containing an oxidizing agent into contact with activated carbon and reducing the oxidizing agent,
In the reduction treatment step, an oxidant treatment method characterized by detecting an amount of at least one of carbon monoxide and carbon dioxide generated by contact between the activated carbon and the oxidant.   The reduction treatment step includes a reducing agent addition step of adding a reducing agent to water containing the oxidizing agent. In the reducing agent addition step, based on the detected amounts of carbon monoxide and carbon dioxide detected, 2. The oxidizing agent treatment method according to claim 1, wherein the amount or concentration of the reducing agent is controlled.   In the reduction treatment step, based on the detected amounts of carbon monoxide and carbon dioxide, the supply amount of water containing the oxidizing agent supplied to the activated carbon or the oxidizing agent in water containing the oxidizing agent 3. The oxidizing agent treatment method according to claim 1, wherein the concentration of the oxidizing agent is controlled.   The said oxidizing agent is a persulfate and a hypochlorite, The oxidizing agent processing method of any one of Claims 1-3 characterized by the above-mentioned. An activated carbon reaction tank for bringing water containing an oxidizing agent into contact with activated carbon and reducing the oxidizing agent;
An oxidant processing apparatus comprising: a detecting unit that detects a generation amount of at least one of carbon monoxide and carbon dioxide generated by contact between the activated carbon and the oxidant. Reducing agent addition means for adding a reducing agent to water containing the oxidizing agent;
Control means for controlling the amount or concentration of the reducing agent added by the reducing agent addition means based on the detected amounts of carbon monoxide and carbon dioxide detected. 5. The oxidizer treatment apparatus according to 5. Supply means for supplying water containing an oxidizing agent to the activated carbon reaction tank;
Based on the detected amounts of carbon monoxide and carbon dioxide, the supply amount of water containing the oxidant supplied to the activated carbon reaction tank by the supply means, or the concentration in water containing the oxidant The oxidant processing apparatus according to claim 5, further comprising a control unit that controls the oxidant.   The said oxidizing agent is a persulfate and a hypochlorite, The oxidizing agent processing apparatus of any one of Claims 5-7 characterized by the above-mentioned.   The oxidant according to any one of claims 5 to 8, wherein the activated carbon reaction tank is an upward flow type activated carbon reaction tank through which water containing the oxidant flows in an upward flow. Processing equipment.

Images