JP2020032412A - Method and equipment for treating cyanide-containing water - Google Patents

Abstract

To provide a method for treating cyanide-containing water possible to carry out stable and sufficient removal of a cyan component from water to be treated even in a case of various concentration of cyanide ions and concentration of iron cyano complexes in the water to be treated.SOLUTION: There is provided a method for treating cyanide-containing water, including: a step (A) of reacting water to be treated containing cyanide ions and iron cyano complexes by adding hydrogen peroxide; a step (B1) of measuring the concentration of the hydrogen peroxide remaining in a reaction solution obtained in the step (A); a step (C) of adding a copper (I) compound to the reaction solution obtained in the step (A) to cause a reaction; and a step (D) of subjecting the reaction solution obtained in the step (C) to a solid-liquid separation treatment, in which an amount of the hydrogen peroxide added to the water to be treated in the step (A) is controlled to an amount such that the hydrogen peroxide concentration measured in the step (B1) is 10 mg-HO/L or less.SELECTED DRAWING: None

Description

  The present invention relates to a method for treating cyanide-containing water and a facility for treating cyanide-containing water.

  BACKGROUND ART As a treatment method for removing a cyan component from waste water containing a cyan component such as cyanide ions, an alkali chlorine method for oxidatively decomposing a cyan component in waste water is widely applied. In the alkali chlorine method, generally, sodium hypochlorite is added to a cyanide-containing wastewater under alkaline conditions to convert cyanide ions in the wastewater and easily decomposable cyano complexes (cyano complexes such as zinc and copper). Can be oxidatively decomposed.

  On the other hand, in the alkali chlorine method, since it is difficult to decompose a hardly decomposable cyano complex such as an iron cyano complex, a cyanide component in wastewater is reacted with a metal salt to generate a hardly soluble salt. Has also been proposed for separating and removing phenol by a precipitation method (a sparingly soluble salt precipitation method). In Patent Literature 1, a specific cuprous compound and hydrogen peroxide are allowed to coexist with complex cyanide-containing wastewater under conditions of pH 6 to 9 to remove water-insoluble salts generated in the wastewater. A method of treating complex cyanide-containing wastewater for treating complex cyanide in wastewater has been proposed.

JP 2017-80699 A

  The present inventors referred to the method proposed in Patent Document 1 and added hydrogen peroxide and a copper (I) compound to various treated waters containing cyanide ions and iron cyano complexes and having different concentrations thereof. A beaker test was conducted in which co-presence was carried out. As a result, it was found that the cyan component could not be sufficiently removed depending on the water to be treated.

  Therefore, the present invention can stably and sufficiently perform the removal process of the cyan component from the water to be treated even when the concentration of cyanide ion and the concentration of the iron cyano complex in the water to be treated are various. It is intended to provide a possible method of treating cyanide-containing water.

  As described above, the present inventors found that when various treatment waters containing a cyanide ion and an iron cyano complex were treated with hydrogen peroxide and a copper (I) compound in the beaker test, the treatment was carried out. The cause of the problem that the performance of removing the cyan component from the treated water was reduced was examined in detail. Specifically, the properties of the water to be treated that have caused such a problem are analyzed, and when hydrogen peroxide and a copper (I) compound are simultaneously added to the water to be treated, The difference in treatment performance between the case where a copper (I) compound was added after the addition of hydrogen oxide, and the like were examined, and the above-mentioned causes were clarified. As a result, when the copper (I) compound is added to the water to be treated, the performance of removing the cyan component from the water to be treated is likely to decrease if a relatively large amount of hydrogen peroxide remains in the water to be treated. I understood.

  Based on such findings, the present inventors have found that when adding a copper (I) compound to a reaction solution obtained by adding hydrogen peroxide to water to be treated and reacting the same, residual hydrogen peroxide in the reaction solution is reduced. The inventors thought that the above-mentioned problem could be solved if the concentration was set to a sufficiently low value or if the residual hydrogen peroxide could be substantially eliminated, and completed the present invention.

That is, the present invention provides a process (A) in which hydrogen peroxide is added to water to be treated containing a cyanide ion and an iron cyano complex to cause a reaction, and a process in which the reaction solution obtained in the process (A) remains. A step (B1) of measuring the concentration of the hydrogen peroxide, a step (C) of adding a copper (I) compound to the reaction solution obtained in the step (A) and causing the reaction, (D) performing a solid-liquid separation treatment on the reaction solution obtained in (C), wherein the amount of the hydrogen peroxide added to the water to be treated in the step (A) is determined in the step (B1). the value of the hydrogen peroxide concentration to be measured is controlled to an amount equal to or less than _{10mg-H 2 O 2 / L} , to provide a method of processing cyan-containing water.

  Further, the present invention provides a step (A) of reacting water to be treated containing cyanide ion and iron cyano complex by adding hydrogen peroxide thereto, and a reaction solution obtained in the step (A), A step (B2) of contacting with a hydrogen peroxide removing agent for reducing the concentration of the hydrogen peroxide remaining in the reaction solution to cause a reaction, and copper (I) added to the reaction solution obtained in the step (B2). Provided is a method for treating cyanide-containing water, which comprises a step (C) of adding a compound to react and a step (D) of subjecting the reaction solution obtained in the step (C) to a solid-liquid separation treatment.

  ADVANTAGE OF THE INVENTION According to this invention, even if the density | concentration of cyanide ion and the density | concentration of an iron cyano complex in to-be-processed water are various, the cyan component which can remove the cyan component from to-be-processed water stably and sufficiently can be performed. A method for treating the contained water can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing showing an example of the schematic structure of the processing equipment which can perform the processing method of the cyan containing water of 1st Embodiment of this invention, and a processing flow. It is explanatory drawing showing an example of the schematic structure of the processing equipment which can perform the processing method of the cyan containing water of 2nd Embodiment of this invention, and a processing flow. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an explanatory diagram illustrating a schematic configuration of an example of an exhaust gas treatment facility and a process flow when it is assumed that a method for treating cyanide-containing water according to an embodiment of the present invention is applied.

  Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

  The present inventors referred to the method proposed in Patent Document 1 and added hydrogen peroxide and a copper (I) compound to various treated waters containing cyanide ions and iron cyano complexes and having different concentrations thereof. A beaker test was carried out in which coexisting was treated, and the processing performance was examined. As a result, it was found that depending on the water to be treated, there was a problem that the cyan component could not be sufficiently removed from the water to be treated.

The iron cyano complex refers to a complex containing Fe and CN. Examples of the iron cyano complex include ferrocyanide ion ([Fe (CN) ₆ ] ^4- ; hexacyanoferrate (II) ion) and ferricyanide ion ([Fe (CN) ₆ ] ^3- ; hexacyanoiron (III) Acid ions), and iron carbonyl cyano complexes ([Fe (CN) ₅ (CO)] ^3- and [Fe (CN) ₄ (CO) ₂ ] ^2- ).

Regarding the cause of the above-mentioned problem, the present inventors analyzed the properties of the water to be treated that caused the problem, and examined the case where hydrogen peroxide and a copper (I) compound were added to the water to be treated at the same time. Investigations were made by confirming the difference in processing performance between the case where a copper (I) compound was added after adding hydrogen, and the like. In the study, it was found that, for example, when the concentration of cyanide ion and the concentration of iron cyano complex in the water to be treated are both low, the above-described problem hardly occurs. On the other hand, it has been found that, for example, when the iron cyano complex concentration is higher than the cyanide ion concentration in the water to be treated, the above problem is likely to occur. In addition, the iron cyano complex contained in the water to be treated contains ferrocyanide ions and / or ferricyanide ions, and [Fe (CN) ₅ (CO)] ^3- and / or [Fe (CN) ) ₄ (CO) ₂ ] ^2- was also found to easily cause the above problem. As described above, it has been found that even if the addition amount of hydrogen peroxide or the copper (I) compound is adjusted depending on the property of the water to be treated, the treatment performance varies.

  Generally, in the actual wastewater containing cyanide (the water to be treated), the concentration of cyanide ions and cyanide components such as iron cyano complex in the wastewater fluctuates every moment. Therefore, in an actual wastewater treatment facility, when hydrogen cyanide and a copper (I) compound coexist in cyanide-containing wastewater for treatment, depending on the cyanide-containing wastewater flowing into the wastewater treatment facility, It is considered that the performance of removing the cyan component may be reduced. In the actual wastewater treatment equipment, when the cyan-containing wastewater in which the above-described problem is unlikely to occur continues, the treatment is continuously performed without noticing the problem, but one day suddenly, the above-described problem easily occurs. The inflow of cyanide-containing wastewater can be confusing.

  Therefore, irrespective of whether or not the above-mentioned problem is likely to occur, even when the concentration of cyanide ion and the concentration of iron cyano complex in the water to be treated are various, the removal of the cyan component from the water to be treated A method capable of performing the treatment stably and sufficiently is actually useful.

  The present inventors have conducted studies to determine the cause of the above problem, and as a result, when adding a copper (I) compound to the water to be treated, a relatively large amount of hydrogen peroxide was present in the water to be treated. It was found that the performance of removing the cyan component from the water to be treated was liable to decrease. Based on such findings, the present inventors have found that when adding a copper (I) compound to a reaction solution obtained by adding hydrogen peroxide to water to be treated and reacting the same, residual hydrogen peroxide in the reaction solution is reduced. The present invention has been completed based on the idea that the above-mentioned problem can be solved if the concentration is set to a sufficiently low value or if the residual hydrogen peroxide can be substantially eliminated.

<Method of treating cyanide-containing water>
The method for treating cyanide-containing water according to the first embodiment of the present invention comprises a step (A) of adding hydrogen peroxide to water to be treated containing cyanide ions and an iron cyano complex to cause a reaction, and the step (A). Step (B1) of measuring the concentration of hydrogen peroxide remaining in the reaction solution obtained in A), and reacting the reaction solution obtained in the above step (A) by adding a copper (I) compound to the reaction solution. The method includes a step (C) and a step (D) of subjecting the reaction solution obtained in the step (C) to a solid-liquid separation treatment, wherein the amount of hydrogen peroxide added to the water to be treated in the step (A) is: The purpose of the present invention is to control the value of the concentration of hydrogen peroxide measured in the above step (B1) to 10 mg-H ₂ O ₂ / L or less.

  Further, the method for treating cyanide-containing water according to the second embodiment of the present invention comprises the steps of: (A) adding hydrogen peroxide to water to be treated containing cyanide ions and an iron cyano complex to cause a reaction; A step (B2) of bringing the reaction solution obtained in the step (A) into contact with a hydrogen peroxide removing agent for reducing the concentration of hydrogen peroxide remaining in the reaction solution to cause a reaction, and the step (B2) (C) adding a copper (I) compound to the reaction solution obtained in (c) and reacting it, and (D) performing a solid-liquid separation treatment on the reaction solution obtained in the step (C). It is in.

According to the method for treating cyan-containing water in the first and second embodiments (these may be collectively simply referred to as “the present embodiment”), first, a cyanide ion and an iron cyano complex (A) is performed by adding hydrogen peroxide to water to be treated (hereinafter, may be simply referred to as “water to be treated”). Thereby, the hydrogen peroxide undergoes an oxidation reaction with cyanide ions (CN ⁻ ) in the water to be treated, and can decompose the cyanide ions. In the case where the water to be treated contains an easily decomposable cyano complex such as a zinc cyano complex, a nickel cyano complex, and a copper cyano complex in addition to CN ⁻ , such a cyano complex is also subjected to the step ( Decomposition can be expected according to A). The reaction time in the step (A) is preferably from 3 to 60 minutes, more preferably from 5 to 30 minutes. Further, the reaction temperature in the step (A) is preferably from 15 to 80 ° C, more preferably from 35 to 60 ° C.

  In the treatment method of the present embodiment, a step (C) of adding a copper (I) compound to the reaction solution obtained in the above step (A) or the reaction liquid obtained in the above step (B2) to cause a reaction. )I do. As a result, the iron cyano complex existing from the water to be treated is made hardly soluble, and a hardly soluble iron cyano complex can be produced in the reaction solution. The reaction time in the step (C) is preferably from 3 to 60 minutes, and more preferably from 5 to 30 minutes. Further, the reaction temperature in the step (C) is preferably from 15 to 80 ° C, more preferably from 35 to 60 ° C.

  The hardly soluble material that can be produced in the step (C) can be separated and removed in the step (D) of subjecting the reaction solution obtained in the step (C) to a solid-liquid separation treatment. Further, by this step (D), treated water from which the cyan component has been removed can be obtained.

  As described above, in the treatment method of the present embodiment, before the addition of the copper (I) compound to the water to be treated, the step (A) of adding and reacting hydrogen peroxide to the water to be treated is performed. I) When a hardly soluble material is produced by adding a compound, the amount of cyan contained in the hardly soluble material can be reduced appropriately. Therefore, the amount of cyan contained in the hardly soluble material is reduced, which leads to an advantage that the possibility and the degree of elution of cyan can be reduced when the hardly soluble material is disposed.

(First embodiment)
Then, in the treatment method of the first embodiment, the amount of hydrogen peroxide added to the water to be treated in the step (A) is obtained in the step (A), which is measured in the step (B1). The concentration of the hydrogen peroxide in the reaction solution is controlled to be 10 mg-H ₂ O ₂ / L or less. Thus, when the copper (I) compound is added to the reaction solution after the reaction by adding hydrogen peroxide to the water to be treated, the concentration of the residual hydrogen peroxide in the reaction solution can be made sufficiently low. . Therefore, even when the concentration of cyanide ion and the concentration of the iron cyano complex in the water to be treated are various, it is possible to stably and sufficiently remove the cyan component from the water to be treated.

In the processing method of the first embodiment, the value of the concentration of hydrogen peroxide measured in the step (B1) is checked and the value of the hydrogen peroxide concentration in the step (A) is reduced to 10 mg-H ₂ O ₂ / L or less. The amount of hydrogen peroxide added to water can be adjusted. Therefore, effective treatment by adding hydrogen peroxide to the water to be treated can be performed more reliably, and treatment efficiency by oxidative decomposition of cyanide ions in the water to be treated can be increased.

The amount of hydrogen peroxide added to the water to be treated in the step (A) is such that the value of the hydrogen peroxide concentration measured in the step (B1) is preferably 5 mg-H ₂ O ₂ / L or less, more preferably 3 mg-H ₂ O ₂ / L. It is preferable to control the amount to be −H ₂ O ₂ / L or less. As a result, the concentration of the residual hydrogen peroxide in the reaction solution at the time of adding the copper (I) compound can be made sufficiently low, so that the cyan component can be more stably removed from various waters to be treated. Easier to do. The lower limit of the value of the hydrogen peroxide concentration measured in the step (B1) is set to 0.1 mg-H ₂ so that an effective treatment by adding hydrogen peroxide to the water to be treated can be more reliably performed. It is preferably at least O ₂ / L, more preferably at least 0.5 mg-H ₂ O ₂ / L.

  The measurement of the hydrogen peroxide concentration in the step (B1) may be performed by a batch method or a continuous method. If hydrogen peroxide is added to the water to be treated in the step (A) while monitoring the value of the hydrogen peroxide concentration measured in the step (B1), while confirming the measured value of the hydrogen peroxide concentration, This is preferable because the amount of hydrogen peroxide added to the water to be treated in the step (A) can be easily adjusted. From the viewpoint of easily adopting such a method, in the step (B1), it is preferable to continuously measure the concentration of hydrogen peroxide remaining in the reaction solution obtained in the step (A). Monitoring of the value of the concentration of hydrogen peroxide measured in the step (B1) can also be performed intermittently (at predetermined intervals) in a batch system.

(Second embodiment)
Then, in the treatment method of the second embodiment, before adding the copper (I) compound to the reaction solution obtained in the step (A), the reaction solution obtained in the step (A) and The step (B2) of contacting with a hydrogen peroxide removing agent that reduces the concentration of hydrogen peroxide remaining in the reaction solution to cause a reaction is performed. As a result, the reaction solution to which the copper (I) compound is added (the reaction solution after the step (A)) can be brought to a state where the concentration of the residual hydrogen peroxide in the reaction solution is sufficiently low. Therefore, even when the concentration of cyanide ion and the concentration of the iron cyano complex in the water to be treated are various, it is possible to stably and sufficiently remove the cyan component from the water to be treated.

  In the step (B2), the contact between the reaction solution obtained in the step (A) and the hydrogen peroxide removing agent may be performed by contacting the reaction solution obtained in the step (A) with the hydrogen peroxide removing agent. The reaction solution obtained in the step (A) may be brought into contact with the hydrogen peroxide removing agent, or both may be carried out. The reaction time in the step (B2) is preferably from 1 to 30 minutes, more preferably from 1 to 15 minutes. In addition, the reaction temperature in the step (B2) is preferably from 15 to 80 ° C, more preferably from 35 to 60 ° C.

In the second embodiment, the reaction in the reaction solution obtained in the step (A) is carried out by the step (B2) in which the reaction solution obtained in the step (A) is brought into contact with the hydrogen peroxide removing agent to cause a reaction. Since the concentration of hydrogen oxide can be reduced, the amount of hydrogen peroxide added to the water to be treated in the step (A) is not particularly limited. The amount of hydrogen peroxide added in this step (A) can be an amount that can sufficiently treat cyanide ions in the water to be treated by oxidative decomposition or the like. The addition amount of the hydrogen peroxide, for example, is preferably _{10~300mg-H 2 O 2 / L} , more preferably _{10~200mg-H 2 O 2 / L} , 10~100mg-H 2 More preferably, it is O ₂ / L.

In the treatment method of the second embodiment, the concentration of hydrogen peroxide remaining in the reaction solution obtained in the step (A) is measured in the same manner as in the step (B1) in the treatment method of the first embodiment. It is preferable that the method further includes a step (B1). If the value of the hydrogen peroxide concentration measured in this step (B1) is 10 mg-H ₂ O ₂ / L or less, the above step (B2) can be omitted. The processing method of the embodiment can be adopted. For this reason, when the value of the hydrogen peroxide concentration measured in the step (B1) is more than 10 mg-H ₂ O ₂ / L, it is particularly significant to perform the step (B2). Further, when the value of the concentration of hydrogen peroxide measured in the step (B1) is 0.1 to 10 mg-H ₂ O ₂ / L, it is sufficiently significant to perform the step (B2). By the step (B2), the concentration of hydrogen peroxide in the reaction solution to which the copper (I) compound is added in the step (C) can be further reduced, whereby the cyan component can be removed from various water to be treated. Is more stably and easily performed.

Further, the treatment method of the second embodiment preferably further includes a step (B3) of measuring the concentration of hydrogen peroxide remaining in the reaction solution obtained in the step (B2). By this step (B3), the effect of reducing the concentration of hydrogen peroxide by the hydrogen peroxide removing agent in step (B2) can be confirmed. In the step (B3), the value of the concentration of hydrogen peroxide measured in the step (B3) is 10 mg-H ₂ O ₂ / L or less (preferably 5 mg-H ₂ O ₂ / L or less, more preferably ₃ mg-H ₂ O ₂ / L or less). (H ₂ O ₂ / L or less) In the step (B2), the amount of the hydrogen peroxide remover used can be adjusted.

  The measurement of the concentration of hydrogen peroxide in the step (B3) may be performed by either a batch method or a continuous method as in the step (B1). In step (B2), the reaction solution obtained in step (A) is brought into contact with the hydrogen peroxide removing agent while monitoring the value of the hydrogen peroxide concentration measured in step (B3). This is preferable because the amount of the hydrogen peroxide remover can be easily adjusted while confirming the effect of the hydrogen remover. From the viewpoint of easily adopting such a method, in the step (B3), it is preferable to measure the concentration of hydrogen peroxide remaining in the reaction solution obtained in the step (B2) by a continuous method. The monitoring of the value of the hydrogen peroxide concentration measured in the step (B3) can also be performed by performing the measurement intermittently (at predetermined intervals) in a batch system.

  In the processing method of the second embodiment, when performing the above steps (B1) and (B3), it is also possible to measure the concentration of hydrogen peroxide in each step using the same measuring device at the same place. is there. Further, the measurement of the hydrogen peroxide concentration in the step (B1) and the step (B3) can be continuously performed in the step (B1) and the step (B3). It is also possible to carry out continuously without distinction.

The hydrogen peroxide removing agent used in the step (B2) in the treatment method of the second embodiment preferably includes one or both of a reducing agent for hydrogen peroxide and a catalyst for decomposing hydrogen peroxide. Examples of the reducing agent for hydrogen peroxide include sulfites such as sodium sulfite (Na ₂ SO ₃ ) and potassium sulfite (K ₂ SO ₃ ); and sodium hydrogen sulfite (NaHSO ₃ ) and potassium hydrogen sulfite (KHSO ₃ ). Bisulfite (also called bisulfite); iron (II) salts such as iron (II) sulfate and iron (II) nitrate (also called divalent iron and ferrous salts); ascorbic acid and its salts Can be mentioned. When a hydrogen peroxide reducing agent such as these is used as a hydrogen peroxide removing agent, a hydrogen peroxide removing agent (hydrogen peroxide reducing agent) is added to the reaction solution obtained in step (A). It is preferable that the reaction solution obtained in the step (A) is brought into contact with a hydrogen peroxide removing agent. Examples of the form in which the reducing agent for hydrogen peroxide is added include a powder form and a solution form dissolved in a solvent, and a solution form is preferable.

  As a decomposition catalyst for hydrogen peroxide, a liquid decomposition catalyst or a solid decomposition catalyst can be used. Examples of the liquid decomposition catalyst include catalase and activated sludge used in sewage treatment plants. Examples of the solid decomposition catalyst include powdered or granular manganese dioxide, and granular or pelletized activated carbon. When the hydrogen peroxide decomposition catalyst as described above is used as a hydrogen peroxide remover, a hydrogen peroxide remover (hydrogen peroxide decomposition catalyst) is added to the reaction solution obtained in the step (A). Preferably, the reaction solution obtained in the step (A) is brought into contact with a hydrogen peroxide removing agent. In addition, a catalyst in which a hydrogen peroxide decomposition catalyst is supported on a base material is immersed in the reaction liquid, or a solid decomposition catalyst, which is processed into a fibrous or mesh shape, is immersed in the reaction liquid. The reaction solution obtained in step (A) is brought into contact with the hydrogen peroxide removing agent (hydrogen peroxide decomposition catalyst) by passing the reaction solution through a tank filled with a solid decomposition catalyst. It is also preferred.

  Next, a preferred configuration common to the processing method of the first embodiment and the processing method of the second embodiment will be described.

As described above, the water to be treated suitable for performing the treatment method of the present embodiment may be the water to be treated having a higher iron cyano complex concentration than the cyanide ion concentration. Further, as a preferable water to be treated, the iron cyano complex contained in the water to be treated contains one or both of a ferrocyanide ion and a ferricyanide ion, and [Fe (CN) ₅ (CO) ] ^3- and [Fe (CN) ₄ (CO) ₂ ] ^2- . Wastewater containing an iron carbonyl cyano complex is disclosed, for example, in JP-A-2018-39004 and JP-A-2018-69227.

The iron carbonyl cyano complex is an environment in which an iron carbonyl complex such as iron pentacarbonyl (Fe (CO) ₅ ) and hydrogen cyanide (HCN) or CN ⁻ coexist; iron (II) ion (Fe ²⁺ ), carbon monoxide. (CO) and an environment where HCN or CN ⁻ coexists; an environment where [Fe (CN) ₆ ] ⁴⁻ and CO coexist; For example, in waste water discharged from factories for performing plating, CN ^- and although iron is likely to coexist, possibly CO and iron pentacarbonyl is present is considered to be low, environmental as described above rare It is considered to be. Therefore, it is considered that in the conventional technology for treating cyanide-containing water, an iron carbonyl cyano complex that can be generated from the above-described environment is rarely treated. The present inventors have confirmed that iron pentacarbonyl was contained in the exhaust gas generated from a furnace using coke as a fuel, and it was found that it could fluctuate greatly depending on the operating conditions of the furnace. Was. Since iron pentacarbonyl is considered to have a property of initiating decomposition in a low-temperature region of 100 ° C. or less, it is considered that the content of iron pentacarbonyl in the exhaust gas fluctuates depending on the temperature distribution in the furnace. There is a possibility that the properties of the coke (and the properties of the coal as the coke raw material) are one of the controlling factors in this temperature distribution. From the above, as an example of a suitable to-be-processed water, a washing wastewater of exhaust gas can be mentioned. As an example of a more preferable water to be treated, the exhaust gas containing a suspended substance is subjected to a wet dust collection treatment, and a solid-liquid separation treatment for removing the suspended substance is performed. Gas cleaning wastewater can be mentioned.

  In the treatment method of this embodiment, the pH of the liquid to be treated when performing the treatment in each step is preferably 5 to 10, more preferably 5.5 to 9.5, and still more preferably 6 to 8. The pH of the liquid to be treated in each step may be adjusted. At that time, for example, a pH adjuster such as hydrochloric acid and sodium hydroxide can be used.

  The copper (I) compound used in step (C) in the treatment method of the present embodiment is a monovalent copper compound (cuprous compound). Examples of the copper (I) compound include copper (I) chloride, copper (I) oxide (cuprous oxide), and copper (I) sulfate. One or more of these copper (I) compounds can be used. Examples of the form of the copper (I) compound when the copper (I) compound is added include a powder form and a solution form dissolved in a solvent, and a solution form is preferable. In step (C) of the present embodiment, it is more preferable to use cuprous oxide (copper (I) oxide) as the copper (I) compound.

  In the step (D) of subjecting the reaction solution obtained in the step (C) to a solid-liquid separation treatment, as described above, when a poorly solubilized iron cyano complex is produced by the addition of the copper (I) compound, it is separated. Can be removed. Further, when other suspended solids (SS) are contained in the water to be treated and the reaction solution obtained in the step (C), the SS can be removed in the step (D). Examples of the method of the solid-liquid separation treatment in the step (D) include a precipitation treatment, a membrane separation treatment, a filtration treatment and the like, and among them, the precipitation treatment is preferable. At the time of the solid-liquid separation treatment, a coagulant may be added to the reaction liquid to be subjected to the solid-liquid separation treatment. Examples of the coagulant include inorganic coagulants such as polyaluminum chloride, aluminum sulfate, ferric polysulfate, and ferric chloride; and polymer coagulants. The above can be used.

  When the method for treating cyan-containing water of the present embodiment is applied to the cleaning wastewater of the exhaust gas obtained by performing the solid-liquid separation treatment on the above-mentioned dust collection water, the treatment method includes the following steps (E) and ( It is preferable to include F). That is, the slurry containing the solid content separated from the liquid component in the step (D) is subjected to one or both of the concentration treatment and the dehydration treatment, and the separated water obtained in the step (E). (F) to the above-mentioned solid-liquid separation treatment for obtaining exhaust gas washing wastewater. The slurry containing a solid content obtained in the step (D) contains a hardly-solubilized substance or the like that can be generated in the above-mentioned step (C). May elute the cyan component. On the other hand, by performing the steps (E) and (F), it is possible to more stably remove the cyan component from the water to be treated. Examples of solid-liquid separation processing for removing suspended substances from dust water obtained by performing wet dust collection processing on exhaust gas containing suspended substances include sedimentation separation processing, membrane separation processing, and filtration processing. Of these, sedimentation separation is preferred.

  In the treatment method of the present embodiment, either one of the water to be treated to which the hydrogen peroxide is added in the step (A) and the reaction solution to which the copper (I) compound is to be added in the step (C) or It is preferable to add a reducing agent to both. Examples of the reducing agent include thiosulfate, sulfite, bisulfite, ferrous chloride, and alkali metal sulfides such as sodium sulfide and sodium tetrasulfide. The above can be used. Examples of cations that form salts in thiosulfate, sulfite, and bisulfite include sodium ion, potassium ion, calcium ion, ammonium ion, and organic ammonium ion. Examples of the form of the reducing agent when added to the water to be treated include a powder form, a solution form dissolved in a solvent, and the like, and a solution form is preferable.

  In the treatment method of the present embodiment, it is preferable to further add a quaternary ammonium compound to the reaction solution to which the copper (I) compound is added in the step (C). The quaternary ammonium compound is a compound having a quaternary ammonium cation, and may be a monomer or a polymer. As the quaternary ammonium compound, a tetraalkylammonium compound, a cationic polymer and the like can be suitably used. Examples of the form in which the quaternary ammonium compound is added include a powder form and a solution form dissolved in a solvent, and a solution form is preferable.

  As the tetraalkylammonium compound, didecyldimethylammonium salt, hexadecyltrimethylammonium salt, dioctyldimethylammonium salt, didodecyldimethylammonium salt, trioctylmethylammonium salt, and benzyldodecyldimethylammonium salt are preferable. Further, the anion paired with the quaternary ammonium cation in these is preferably a halide ion, more preferably a chloride ion and a bromide ion.

  As the cationic polymer, any polymer having a quaternary ammonium cation may be used. Examples thereof include a salt-acrylamide copolymer-based compound, a polycondensate of dimethylamine and epichlorohydrin, and a polycondensate of dimethylamine, epichlorohydrin and ammonia.

  In the treatment method of the present embodiment, the step (A) using hydrogen peroxide and the step (C) using the copper (I) compound may be performed in a common reaction tank, or may be performed in separate reaction tanks. Is also good. For example, in the processing method of the first embodiment, when the steps (A) and (C) are performed in a common reaction tank, the addition of hydrogen peroxide and the addition of hydrogen peroxide are performed in the common reaction tank. Can be measured and the copper (I) compound can be added to the reaction solution obtained after the reaction. After terminating the reaction with hydrogen peroxide in the step (A) (more preferably, after the hydrogen peroxide is consumed by the reaction), it is preferable to proceed to the next step, so that the steps (A) and ( And C) are preferably performed in separate reaction tanks.

  In addition, in the treatment method of the second embodiment described above, when used in a mode in which a hydrogen peroxide removing agent is added in the step (B2), a step (A) of adding hydrogen peroxide and a step of removing hydrogen peroxide are included. The step (B2) of adding the agent may be performed in a common tank. Similarly, in this case, the step (B2) of adding the hydrogen peroxide removing agent and the step (C) of adding the copper (I) compound may be performed in a common tank. (B2) and (C) may be performed in a common tank, or may be performed in separate tanks. For example, in the processing method of the second embodiment, when the step (A) and the step (B2) are performed in a common tank, the addition of hydrogen peroxide and the removal of the hydrogen peroxide removing agent are performed in the common tank. Addition, and if necessary, measurement of the concentration of residual hydrogen peroxide in the reaction solution after the reaction with hydrogen peroxide or after the reaction with the hydrogen peroxide removing agent can be performed. When the step (B2) and the step (C) are performed in a common tank, the addition of a hydrogen peroxide removing agent, the addition of a copper (I) compound, and the The concentration of the residual hydrogen peroxide in the reaction solution before the addition of the hydrogen remover or after the reaction with the hydrogen peroxide remover can be measured. When the steps (A), (B2), and (C) are performed in a common tank, addition of hydrogen peroxide, addition of a hydrogen peroxide remover, addition of a copper (I) compound, and Accordingly, the concentration of residual hydrogen peroxide in the reaction solution after the reaction with hydrogen peroxide or after the reaction with the hydrogen peroxide removing agent can be measured. It is preferable to proceed to the next step after terminating the reaction with hydrogen peroxide in step (A), and to proceed to the next step after terminating the reaction with the hydrogen peroxide removing agent in step (B2). From the viewpoint of being preferable, it is preferable that the step (A), the step (B2), and the step (C) are performed in separate tanks.

  Hereinafter, with respect to each step in the method for treating cyanide-containing water of the first embodiment and the second embodiment, referring to the drawings showing a schematic configuration of a treatment facility and a treatment flow capable of executing the treatment method, State. Note that the same reference numerals are given to parts common to the drawings in the drawings, and description thereof may be omitted. 1 and 2 indicate the water to be treated and the treatment process thereof.

  FIG. 1 is an explanatory diagram illustrating an example of a schematic configuration of a processing facility and a processing flow capable of executing the method of treating cyan-containing water according to the first embodiment. As shown in FIG. 1, the processing equipment 10 includes a first reaction tank (a) 11, a hydrogen peroxide concentration measuring device (b1) 13, a second reaction tank (c) 12, and a solid-liquid separation device (d). ) 16 and a control unit 17. The above-mentioned step (A) is performed in the first reaction tank (a) 11, the above-described step (B1) is performed in the measuring device (b1) 13, and the above-described step (B) is performed in the second reaction tank (c) 12. The above-mentioned step (D) can be performed on the solid-liquid separator (d) 16 for the step C). Hereinafter, descriptions of (a), (b1), (c), and (d) will be omitted.

The first reaction vessel 11, the water to be treated W ₁₀ that has been flowing a bath and reacted with hydrogen peroxide. The first reaction tank 11 can be provided with a device (hydrogen peroxide addition device) 111 for adding hydrogen peroxide. The second reaction vessel 12 is a bath with the addition of copper (I) compound is reacted in the reaction liquid W ₁₁ obtained in the first reaction vessel 11. The second reaction tank 12 can be provided with a device (copper (I) compound addition device) 121 for adding a copper (I) compound. Solid-liquid separator 16 is a device for solid-liquid separation of the reaction liquid W ₁₂ obtained in the second reaction vessel 12. As the solid-liquid separator 16, for example, a sedimentation device such as a thickener, various filters, a membrane separator, and the like can be used. When a coagulant is used in the treatment by the solid-liquid separation device 16, a device (coagulant addition device) for adding the coagulant may be provided in the solid-liquid separation device 16. The hydrogen peroxide addition device 111, the copper (I) compound addition device 121, and the flocculant addition device include, for example, a tank for storing each material, and a pump and a supply pipe for supplying each material. Can be. The processing equipment 10 may include a relay tank, for example, between the second reaction tank 12 and the solid-liquid separation device 16.

  In the case where the reducing agent such as the above-mentioned thiosulfate is used together with hydrogen peroxide in the step (A), the first reaction tank 11 is provided with an apparatus for adding the reducing agent to the first reaction tank 11 ( A reducing agent addition device). In the case where the above-mentioned reducing agent or the above-mentioned quaternary ammonium compound is used together with the copper (I) compound in the step (C), the second reaction tank 12 may be provided with a reducing agent addition device or a second reaction device. An apparatus for adding a quaternary ammonium compound to the tank can be provided.

Hydrogen peroxide concentration of the measurement device 13 is a device for measuring the concentration of hydrogen peroxide remaining in the reaction liquid W ₁₁ obtained in the first reaction vessel 11. As the hydrogen peroxide concentration measuring device 13, any of a batch-type measuring device and a continuous-type measuring device can be used, and a continuous-type measuring device is more preferable. As the batch type measuring device, for example, trade names “RQ Flex” and “Reflectant peroxide test” (manufactured by Kanto Chemical Co., Ltd.) can be used. Further, as the continuous measuring device, for example, a product name “Q46 / 84 type hydrogen peroxide meter” (manufactured by ATI) can be used.

Control unit 17, the first reaction vessel the amount of hydrogen peroxide to water to be treated W ₁₀ in 11, the value of the hydrogen peroxide concentration is 10 mg-H ₂ as measured by the measuring device 13 of the hydrogen peroxide concentration The amount is controlled so as to be O ₂ / L or less. From the viewpoint of easy control, the control unit 17 preferably cooperates with the hydrogen peroxide concentration measuring device 13 and the first reaction tank 11 (the hydrogen peroxide adding device 111 provided therein). For example, when the value of the hydrogen peroxide concentration measured by the measuring device 13 is within a predetermined range (for example, in the range of 0 to 5 mg-H ₂ O ₂ / L), the hydrogen peroxide adding device 111 (injection pump) operates. The measuring unit 13 and the hydrogen peroxide adding device 111 (injection pump) are linked by the control unit 17 so that the hydrogen peroxide adding device 111 (injection pump) is stopped when the upper limit of the predetermined range is exceeded. Can be. The control unit 17 can be configured to include, for example, a power supply unit, a CPU unit, an input unit, an output unit, and a storage unit, and can use a personal computer.

  In FIG. 1, the first reaction tank 11 and the second reaction tank 12 are separated so that the step (A) using hydrogen peroxide and the step (C) using a copper (I) compound can be easily described. Although shown separately, the first reaction tank 11 and the second reaction tank 12 may be the same (common) reaction tank. On the other hand, after the reaction with hydrogen peroxide in step (A) is completed (more preferably, after hydrogen peroxide is consumed by the reaction), it is preferable to proceed to the next step. It is preferable that 11 and the second reaction tank 12 be separate tanks. In addition, in FIG. 1, the hydrogen peroxide concentration measuring device 13 is provided in FIG. 1 so that the step (B1) of measuring the concentration of hydrogen peroxide remaining in the reaction solution obtained in the step (A) can be easily described. Although provided between the first reaction tank 11 and the second reaction tank 12 (flow path therebetween), it may be provided in the first reaction tank 11 or may be provided in the above-described common reaction tank. You may.

  FIG. 2 is an explanatory diagram illustrating an example of a schematic configuration of a processing facility and a processing flow capable of executing the method of treating cyan-containing water according to the second embodiment. As shown in FIG. 2, the processing equipment 20 includes a first reaction tank (a) 21, a removal tank (b2) 24, a second reaction tank (c) 22, and a solid-liquid separation device (d) 26. . The first step (A) is performed in the first reaction tank (a) 21, the step (B2) is performed in the removal tank (b2) 24, and the second step is performed in the second reaction tank (c) 22. The above-mentioned step (D) can be performed on C) in the solid-liquid separation device (d) 26. Hereinafter, description of (a), (b2), (c), and (d) will be omitted.

The first reaction tank 21 in the processing equipment 20 shown in FIG. 2 is the same as the first reaction tank 11 in the processing equipment 10 described above. Further, solid-liquid separator 26 for solid-liquid separation of the reaction liquid W ₂₂ obtained in the second reaction tank 22 in the processing equipment 20 is similar to the solid-liquid separator 16 in the processing equipment 10 described above. Further, the second reaction tank 22 in the processing equipment 20 shown in FIG. 2 is the same as the second reaction tank 12 in the processing equipment 10 shown in FIG. 1 except that the liquid flowing therein is different. The processing equipment 20 may also include a relay tank, for example, between the second reaction tank 22 and the solid-liquid separation device 26.

Removing tank 24 is a tank reaction liquid W ₂₁ obtained in the first reaction tank 21 is introduced, and the reaction solution W _21, a bath is reacted by contacting the above-mentioned hydrogen peroxide removers is there. At this removing tank 24, it is possible that the concentration of hydrogen peroxide remaining in the reaction solution W ₂₁ to obtain a reaction liquid W ₂₄ with reduced. The removing tank 24 may be provided with a device 241 for the reaction liquid W ₂₁ obtained in the first reaction vessel 21 to addition of hydrogen peroxide removal agent (tank, pump, and supply tube, etc.). When the above-mentioned decomposition catalyst is used as the hydrogen peroxide removing agent, a substrate supporting the decomposition catalyst may be provided in the removal tank 24. By causing pass through the reaction liquid W ₂₁ obtained in the first reaction tank 21 to the removing tank 24, a substrate having supported thereon the cracking catalyst may be immersed in the reaction liquid W _21. Further, when the above-mentioned solid decomposition catalyst is used as the hydrogen peroxide removing agent, the removal tank 24 may be a tank filled with the solid decomposition catalyst. Its removing tank 24, by passing the reaction liquid W ₂₁ obtained in the first reaction vessel 21, it may be brought into contact with the reaction liquid W ₂₁ and hydrogen peroxide scavenging agent.

Processing equipment 20, the residual and the first measuring device of the hydrogen peroxide concentration remaining in the reaction liquid W ₂₁ obtained in reaction vessel 21 (b1) 23, to the reaction solution W ₂₄ obtained in removing tank 24 It is preferable to provide a measuring device (b3) 25 for measuring the concentration of hydrogen peroxide. The above-described step (B1) can be performed by the measuring device (b1) 23, and the above-described step (B3) can be performed by the measuring device (b3) 25. These measuring devices 23 and 25 can be the same as the hydrogen peroxide concentration measuring device 13 in the processing equipment 10 shown in FIG. 1 described above, and can also cooperate with the control unit described above. It is.

The example in which the hydrogen peroxide concentration measuring devices 23 and 25 are provided to facilitate the description of the above-described steps (B1) and (B3) has been described. However, instead of the measuring devices 23 and 25, the steps (B1) and The same (common) measuring device 27 can be used in each of the steps (B3). In this case, installing the measuring apparatus 27 of the hydrogen peroxide concentration in removing tank 24, in removing tank 24, and measurement of the residual hydrogen peroxide concentration in the reaction solution _{W 21} (step (B1)), the reaction liquid _{W 24} The measurement of the concentration of residual hydrogen peroxide therein (step (B3)) can be performed.

The hydrogen peroxide concentration measuring device 27 can also cooperate with the control unit described above. Specifically, the value of the concentration of hydrogen peroxide measured by the measuring device 27 is equal to or less than a predetermined value (for example, 10 mg-H ₂ O ₂ / L or less, more preferably 5 mg-H ₂ O ₂ / L or less, and still more preferably The control unit controls the measuring device 27 and the hydrogen peroxide removing agent addition device 241 (injection pump) so that the pressure is 3 mg-H ₂ O ₂ / L or less, particularly preferably 0 mg-H ₂ O ₂ / L. ) Is preferably linked. For example, when the value of the hydrogen peroxide concentration measured by the measuring device 27 exceeds the above-mentioned predetermined value, the hydrogen peroxide removing agent adding device 241 (injection pump) is operated, and the hydrogen peroxide measured by the measuring device 27 is measured. The measuring device 27 and the hydrogen peroxide remover adding device 241 (injection pump) are linked so that the hydrogen peroxide removing agent adding device 241 (injection pump) stops when the concentration value becomes equal to or less than the predetermined value. Can be done.

  In FIG. 2, the first step (A) using hydrogen peroxide, the step (B2) using a hydrogen peroxide remover, and the first step (C) using a copper (I) compound are described in order to facilitate the explanation. Although the reaction tank 21, the removal tank 24, and the second reaction tank 22 are shown separately, the first reaction tank 21 and the removal tank 24; the removal tank 24 and the second reaction tank 22; The tank 21, the removal tank 24, and the second reaction tank 22; may be the same (common) tank. On the other hand, after terminating the reaction with hydrogen peroxide in the step (A) (more preferably, after the hydrogen peroxide is consumed by the reaction), it is preferable to proceed to the next step, and in the step (B2) Since it is preferable to proceed to the next step after terminating the reaction with the hydrogen peroxide removing agent, the first reaction tank 21, the removal tank 24, and the second reaction tank 22 should be separate tanks, respectively. Is preferred.

  In addition, in FIG. 2, the hydrogen peroxide concentration measuring device 23 is provided between the first reaction tank 21 and the removal tank 24 (the flow path therebetween) so that the step (B1) that can be performed as necessary is easily described. 2), the measuring device 23 may be installed in the first reaction tank 21 or may be installed in the above-mentioned common tank that also serves as the first reaction tank 21. Further, in FIG. 2, a hydrogen peroxide concentration measuring device 25 is provided between the removal tank 24 and the second reaction tank 22 (the flow path therebetween) so that the step (B3) that can be performed as necessary is easily described. 2), the measuring device 25 may be installed in the removal tank 24, or may be installed in the common tank that also serves as the removal tank 24.

  As described above, since the wastewater to be treated is preferably the wastewater for cleaning the exhaust gas, the method for treating cyanide-containing water according to the present embodiment can also be applied to a facility for treating the wastewater for cleaning the exhaust gas. FIG. 3 is an explanatory diagram illustrating a schematic configuration of an example of an exhaust gas treatment facility and a process flow when it is assumed that the method for treating cyanide-containing water of the present embodiment is applied.

The exhaust gas G treatment equipment 300 shown in FIG. 3 includes a wet dust collector (Venturi scrubber) 301 for continuously cleaning the exhaust gas G, and a sedimentation tank for sedimenting and separating the collected water W ₃₀₁ obtained from the wet dust collector 301. It includes a 302, a primary treating tank 303 for storing a supernatant W ₃₀₂ obtained by sedimentation as the primary treatment water. In addition, a part of the supernatant liquid (primary treatment water) sent to the primary treatment water tank 303 is returned to the wet dust collector 301 as the circulating water W ₃₀₃ while the makeup water W ₃₀₄ is added thereto, and is used for cleaning the exhaust gas G. It may be used repeatedly. Further, a dehydrator 38 for dehydrating the sediment S ₃₀₂ obtained by sedimentation and separation in the sedimentation tank 302 may be provided, and a part of the dehydrated water treated by the dehydrator 38 is processed as a dewatered cake C. parts may be retransmitted to the settling tank 302 as releasing liquid (dehydrated filtrate) W _38.

When the primary treated water in the primary treated water tank 303 contains cyanide ions and an iron cyano complex, the primary treated water is treated in the method for treating cyanogen-containing water according to the present embodiment. it can be water _{W 10.} In FIG. 3, the primary treatment water in the primary treatment water tank 303 is sent to the above-described treatment facilities 10 and 20 (the first reaction tanks 11 and 21 thereof) as blow water (water to be treated W ₁₀ ), and this embodiment is performed. The case of performing the method for treating cyanogen-containing water described above is exemplified. The slurry containing the solid content separated from the liquid component by the solid-liquid separation devices 16 and 26 in the processing facilities 10 and 20 is sent to a dehydrator 38 for dehydration treatment, and the separated water (desorbed liquid) obtained by the dehydrator 38 , Dehydration filtrate) to the precipitation tank 302. The dehydrator 38 shown in FIG. 3 may be a concentration tank, and the concentration tank and the dehydrator 38 may be used in combination. Further, in addition to the dehydrated filtrate, the separated water obtained in the concentration tank or the excess slurry may be sent to the precipitation tank 302. Note that, instead of the sedimentation tank 302, various types of membrane separation devices, filters, and the like may be used.

The treatment technology for cyan-containing water described above can have the following configuration.
[1] A step (A) in which hydrogen peroxide is added to water to be treated containing cyanide ions and an iron cyano complex to cause a reaction, and the reaction time remaining in the reaction solution obtained in the step (A). A step (B1) of measuring the concentration of hydrogen oxide, a step (C) of adding a copper (I) compound to the reaction solution obtained in the step (A) to cause a reaction, and a step (C) of the reaction. (D) performing a solid-liquid separation treatment on the obtained reaction solution, and the amount of the hydrogen peroxide added to the water to be treated in the step (A) is measured in the step (B1). controlling the amount of the value of the hydrogen peroxide concentration of less than _{10mg-H 2 O 2 / L} , the processing method of the cyan-containing water.
[2] The addition amount of the hydrogen peroxide to the water to be treated in the step (A) is adjusted so that the value of the hydrogen peroxide concentration measured in the step (B1) is 5 mg-H ₂ O ₂ / L or less. The method for treating cyan-containing water according to the above [1], wherein the amount is controlled to be:
[3] The above-mentioned [1] or [1], wherein the hydrogen peroxide is added to the water to be treated in the step (A) while monitoring the value of the hydrogen peroxide concentration measured in the step (B1). 2] The method for treating cyan-containing water according to [2].
[4] Step (A) of adding hydrogen peroxide to water to be treated containing cyanide ion and iron cyano complex to cause a reaction, the reaction solution obtained in the step (A), and the reaction solution (B2) contacting with a hydrogen peroxide removing agent for reducing the concentration of the hydrogen peroxide remaining in the step (B2), and adding a copper (I) compound to the reaction solution obtained in the step (B2). And a step (D) of subjecting the reaction solution obtained in the step (C) to a solid-liquid separation treatment.
[5] The method for treating cyan-containing water according to the above [4], further comprising a step (B1) of measuring a concentration of the hydrogen peroxide remaining in the reaction solution obtained in the step (A).
[6] The cyan-containing water according to the above [4] or [5], further including a step (B3) of measuring the concentration of the hydrogen peroxide remaining in the reaction solution obtained in the step (B2). Processing method.
[7] The cyan-containing water according to any of the above [4] to [6], wherein the hydrogen peroxide removing agent contains one or both of a hydrogen peroxide reducing agent and a hydrogen peroxide decomposition catalyst. Processing method.
[8] In the step (A), the cyanide ion in the water to be treated is decomposed by the hydrogen peroxide, and in the step (C), the compound is obtained in the step (C) by the copper (I) compound. The cyan-containing water according to any one of the above [1] to [7], wherein a hardly soluble product of the iron cyano complex is generated in the obtained reaction solution, and the hardly soluble material is separated and removed in the step (D). Processing method.
[9] The water to be treated is obtained by subjecting the exhaust gas containing suspended substances to a solid-liquid separation treatment for removing the suspended substances from dust collected water obtained by wet dust collection. A step (E) of performing one or both of a concentration treatment and a dehydration treatment on the slurry containing the solid content which is the washing wastewater and is separated from the liquid component in the step (D); A step (F) of sending the obtained separated water to the solid-liquid separation treatment for obtaining the washing wastewater of the exhaust gas, the cyan-containing water according to any one of the above [1] to [8]. Processing method.
[10] One of the water to be treated to which the hydrogen peroxide is added in the step (A) and the reaction solution to which the copper (I) compound is added in the step (C) Alternatively, the method for treating cyan-containing water according to any one of the above [1] to [9], wherein a reducing agent is further added to both.
[11] The cyan according to any of [1] to [10] above, wherein a quaternary ammonium compound is further added to the reaction solution to which the copper (I) compound is added in the step (C). How to treat contained water.
[12] The method of treating cyan-containing water according to any one of [1] to [11], wherein the step (A) and the step (C) are performed in separate reaction tanks.
[13] The iron cyano complex contains one or both of a ferrocyanide ion and a ferricyanide ion, and [Fe (CN) ₅ (CO)] ^3- and [Fe (CN) ₄ (CO) ₂ ] The method for treating cyan-containing water according to any one of the above [1] to [12], including one or both of ^2- .
[14] A reaction tank (a) in which hydrogen peroxide is added to water to be treated containing a cyanide ion and an iron cyano complex to cause a reaction, and remains in the reaction solution obtained in the reaction tank (a). A measuring device (b1) for measuring the concentration of the hydrogen peroxide, a reaction tank (c) for adding and reacting a copper (I) compound to the reaction solution obtained in the reaction tank (a), A solid-liquid separation device (d) for solid-liquid separation of the reaction solution obtained in the reaction tank (c), and an amount of the hydrogen peroxide added to the water to be treated in the reaction tank (a) is measured by the measurement device A control unit that controls the value of the concentration of hydrogen peroxide measured in (b1) to be equal to or less than 10 mg-H ₂ O ₂ / L.
[15] A reaction tank (a) in which hydrogen peroxide is added to water to be treated containing a cyanide ion and an iron cyano complex to cause a reaction, and remains in the reaction solution obtained in the reaction tank (a). A removal tank (b2) for adding and reacting a hydrogen peroxide removing agent for reducing the concentration of hydrogen peroxide, and a copper (I) compound added to the reaction solution obtained in the removal tank (b2). A facility for treating cyanogen-containing water, comprising: a reaction tank (c) for reacting; and a solid-liquid separation device (d) for solid-liquid separation of the reaction solution obtained in the reaction tank (c).

  Hereinafter, the effects of the method for treating cyanide-containing water of one embodiment of the present invention will be described more specifically with reference to Test Examples, but the present invention is not limited to the following Test Examples.

<Test Example 1>
(Water to be treated)
Water to be treated containing 2.0 mg-CN / L of cyanide ion (soluble F-CN) and 11.6 mg-CN / L of soluble cyano complex (soluble complex CN) (soluble total cyanide ( T-CN) concentration of 13.6 mg-CN / L). Specifically, it is obtained by settling and separating wastewater containing suspended substances such as unburned carbon, iron, and zinc, which is discharged from an exhaust gas treatment device that cleans exhaust gas in a predetermined factory. Supernatant water (suspended substance concentration = 48 mg / L) was prepared as water to be treated. The water to be treated was analyzed using the apparatus (liquid chromatography-inductively coupled plasma mass spectrometry (LC-ICP-MS)) and conditions described in JP-A-2018-69227. Include 0.9 mg-CN / L ferrocyanide ion ([Fe (CN) ₆ ] ⁴⁻ ) and 0.3 mg-CN / L ferricyanide ion ([Fe (CN) ₆ ] ³⁻ ) , 9.1 mg-CN / L iron carbonyl cyano complex (5.8 mg-CN / L [Fe (CN) ₅ (CO)] ^3- and 3.3 mg-CN / L [Fe (CN) ₄ ( CO) ₂ ] ^2- ) and 1.3 mg-CN / L of [Cu (CN) ₃ ] ^3- . Further, the water to be treated has a pH of 7.7, a suspended substance (SS) of 36 mg / L, a COD of 11 mg / L, a TN (total nitrogen) of 130 mg / L, and a TP (total phosphorus). Was 0.1 mg / L and inorganic carbon was 310 mg / L. These and the above-mentioned soluble F-CN and soluble T-CN were measured by the method described in JIS K0102: 2013.

(Test Examples 1.1 to 1.3)
500 mL of the water to be treated, which was adjusted to pH 6.8 and a temperature of 50 ° C., was placed in a beaker, 35% by mass of hydrogen peroxide solution was added, and the mixture was reacted for 15 minutes with stirring to obtain a reaction solution (step (A)). . The addition amount of the aqueous hydrogen peroxide, hydrogen peroxide concentration remaining in the reaction solution is controlled to be less than _{10mg-H 2 O 2 / L} , as H 2 _{O 2,} the addition amount (hereinafter shown in Table 1 , “H ₂ O ₂ addition amount”). In Test Example 1.3, 20 mg / L of sodium thiosulfate was added together with hydrogen peroxide. The concentration of hydrogen peroxide remaining in the reaction solution (hereinafter, referred to as “residual H ₂ O ₂ concentration”) was measured (step (B1)). For this measurement, trade names "RQ Flex" and "Reflectquant peroxide test" (manufactured by Kanto Chemical Co., Ltd.) were used.

  Next, a cuprous oxide solution was added to the above reaction solution as copper (Cu) in an amount shown in Table 1, and reacted with stirring for 15 minutes (step (C)). As the cuprous oxide solution, a solution prepared by dissolving cuprous oxide in 35% by mass hydrochloric acid and adjusting the copper (Cu) concentration to 5% by mass was used. In Test Examples 1.2 and 1.3, 30 mg / L of a quaternary ammonium compound, didecyldimethylammonium chloride, was added to the above reaction solution together with cuprous oxide.

  1 mg / L of an anionic polymer flocculant (trade name "KEA-730", manufactured by Nippon Steel Environment Co., Ltd.) was added to the reaction solution obtained after adding and reacting cuprous oxide and the like under stirring. . The reaction solution to which the coagulant was added was allowed to stand, and the hardly soluble (poorly soluble in water) cyanide compound generated in the reaction solution was precipitated to perform solid-liquid separation, and the resulting supernatant water was used as treated water ( Step (D)). With respect to this treated water, the total cyanide concentration of the treated water (referred to as “treated water T-CN” in Table 1) was measured based on the method for analyzing all the cyan specified in JIS K0102: 2013. The stirring during the above-described reactions was performed by using a magnetic stirrer.

(Test Examples 1.4 to 1.6)
In Test Example 1.4, the treatment was performed in the same procedure and method as in Test Example 1.1, except that the added amount of H ₂ O ₂ was changed to the amount shown in Table 1 and that cuprous oxide was not used. Was done. In Test Example 1.5, an aqueous solution of hydrogen peroxide was added without controlling the residual H ₂ O ₂ concentration to be 10 mg / L or less, and the added amount of H ₂ O _{2 and the} added amount of cuprous oxide were shown in a table. Except having changed as shown in No. 1, it processed by the procedure and method similar to Experiment 1.1. In Test Example 1.6, a hydrogen peroxide solution was added without controlling the residual H ₂ O ₂ concentration to be 10 mg / L or less, and the amount of H ₂ O ₂ added was changed as shown in Table 1. Except for the above, the treatment was performed in the same procedure and method as in Test Example 1.3. And about the treated water obtained by Test Examples 1.4 to 1.6, the treated water T-CN was measured based on the above-mentioned analysis method.

  Table 1 shows test conditions and treated water T-CN of Test Examples 1.1 to 1.6.

As shown in Table 1, in Test Examples 1.1 to 1.3, hydrogen peroxide and a copper (I) compound were added, and the added amount of H ₂ O ₂ was obtained after the reaction with hydrogen peroxide. By controlling the residual H ₂ O ₂ concentration in the reaction solution to be 10 mg-H ₂ O ₂ / L (and further 5 mg-H ₂ O ₂ / L) or less, the treated water T-CN is sufficiently reduced. It was confirmed that the cyan component could be highly removed from the water to be treated.

On the other hand, in Test Example 1.4, since the copper (I) compound was not used, the ability to remove the cyan component from the water to be treated was hardly recognized. In Test Example 1.5, hydrogen peroxide and a copper (I) compound were used. In Test Example 1.6, sodium thiosulfate was further used together with hydrogen peroxide, and the fourth compound was further used together with the copper (I) compound. Although the quaternary ammonium salt was used, the concentration of the residual H ₂ O _{2 in} the reaction solution when the copper (I) compound or the like was added was 30 mg-H ₂ O ₂ / L or more, so that the treated water T-CN was sufficiently And the cyan component could not be highly removed from the water to be treated.

<Test Example 2>
In Test Example 2, four types of water to be treated having different cyan component concentrations were prepared, as shown in the “treatment water” column of Table 2. The water to be treated was also analyzed in the same manner as the water to be used in Test Example 1 described above. As a result, [Fe (CN) ₆ ] ⁴⁻ , It was confirmed that [Fe (CN) ₆ ] ^3- , [Fe (CN) ₅ (CO)] ^3- , and [Fe (CN) ₄ (CO) ₂ ] ^2- were contained.

(Test Examples 2.1 to 2.6)
The amounts of H ₂ O ₂ , sodium thiosulfate, cuprous oxide, and didecyldimethylammonium chloride (quaternary ammonium compound) added to the water to be treated shown in Table 2 were as shown in Table 2. Except for the above, treatment was performed in the same procedure and method as in Test Examples 1.1 to 1.3 to obtain treated water.

(Test Examples 2.7 to 2.11)
In Test Examples 2.7 to 2.11, aqueous hydrogen peroxide was added without controlling the residual H ₂ O ₂ concentration to be 10 mg / L or less, and H ₂ O ₂ , sodium thiosulfate, and cuprous oxide were added. And didecyldimethylammonium chloride (quaternary ammonium compound) were treated according to the same procedures and methods as in Test Examples 1.1 to 1.3, except that the addition amounts were as shown in Table 2. To obtain treated water.

  For each of the treated waters obtained in Test Examples 2.1 to 2.11, the total cyanide concentration of the treated water (in Table 2, “treated water T-CN”) was determined in the same manner as described in Test Example 1. This was measured.) The results are shown in Table 2.

As shown in Table 2, not only the water to be treated having a low concentration of each of the soluble F-CN and the soluble complex CN, but also the water to be treated having a higher concentration of the soluble complex CN than the concentration of the soluble F-CN. Also, by controlling the added amount of H ₂ O _{2 so} that the residual H ₂ O ₂ concentration is 10 mg / L or less, the treated water T-CN can be sufficiently reduced, and the cyan component from the treated water can be reduced. Was confirmed to have been highly removed.

<Test Example 3>
Wastewater discharged from the exhaust gas cleaning equipment, containing 2.0 mg-CN / L of cyanide ion (soluble F-CN) and 5.2 mg-CN / L of iron cyano complex (soluble complex CN). The wastewater contained was collected. This wastewater was also analyzed in the same manner as the water to be treated used in Test Example 1 described above. As a result, [Fe (CN) ₆ ] ^4- , [Fe (CN) ₆ ] ^3- , [Fe (CN) ₅ ( CO)] ^<3- > and [Fe (CN) ₄ (CO) ₂ ] ^2- . KCN was added to this wastewater, and a simulated wastewater in which the F-CN concentration shown in Table 3 was adjusted was used.

In Test Example 3, the simulated wastewater was used as the water to be treated, the concentration of residual H ₂ O ₂ in the reaction solution obtained after adding hydrogen peroxide to the water to be treated, and the treated water T-CN. From the measurement results, a test was conducted to study the optimum amount of added H ₂ O ₂ according to the water to be treated.

H ₂ O ₂ was added to the water to be treated having a soluble F-CN concentration shown in Table 3 at an addition amount of 15 mg / L, 30 mg / L, or 70 mg / L, and 20 mg / L of sodium thiosulfate was added. Then, the mixture was reacted for 15 minutes while stirring with a magnetic stirrer to obtain a reaction solution, and the residual H ₂ O ₂ concentration in the reaction solution was measured. The results are shown in Table 3-1.

  After adding hydrogen peroxide and sodium thiosulfate to the water to be treated and reacting, 20 mg-Cu / L of cuprous oxide and 30 mg / L of didecyldimethylammonium chloride were added to the reaction solution, and a magnetic stirrer was added. The mixture was reacted for 15 minutes while stirring at, to obtain a reaction solution. For this reaction solution, treated water was obtained by the same method as described in the description of Test Examples 1.1 to 1.3, and treated water T-CN was measured. The results are shown in Table 3-2.

  From the results of Test Example 3, in the case of the water to be treated containing the soluble complex CN of about 5 mg-CN / L, a suitable amount of hydrogen peroxide to be added is determined according to the concentration of the soluble F-CN in the water to be treated. It is thought that it can be inferred. An example is shown in Table 3-3.

<Test Example 4>
(Test Examples 4.1 and 4.2)
In the same water to be treated as that used in Test Example 1, at pH 6.8 and a water temperature of 50 ° C., an amount of 35% by mass of hydrogen peroxide and an amount of H ₂ O ₂ shown in Table 4 and 20 mg of sodium thiosulfate were added. / L was added thereto and reacted for 5 minutes while stirring with a magnetic stirrer to obtain a reaction solution (step (A)). Further, in the same manner as in Test Example 1, the concentration of residual H ₂ O ₂ in the reaction solution was measured (step (B1)).

Next, sodium sulfite was added to the reaction solution obtained after the addition and reaction of H ₂ O ₂ and sodium thiosulfate as an agent for removing hydrogen peroxide (H ₂ O ₂ ) shown in Table 4 (Na ₂ (Amount added as SO ₃ ), and reacted for 5 minutes while stirring with a magnetic stirrer (step (B2)). Then, the residual H ₂ O ₂ concentration in the obtained reaction solution was measured in the same manner as described above (step (B3)). For the addition of sodium sulfite, a 30% by mass aqueous solution of sodium sulfite was used.

20 mg-Cu / L of cuprous oxide was added to the above reaction solution obtained after the addition and reaction of Na ₂ SO ₃ and reacted for 15 minutes (step (C)). Then, similarly to the method described in Test Example 1, after obtaining treated water (step (D)), the treated water T-CN was measured.

(Test Example 4.3)
In Test Example 4.3, in the step (B2), cuprous oxide was added to the reaction solution obtained after the addition and reaction of H ₂ O ₂ without using an H ₂ O ₂ remover such as sodium sulfite. Except for this, the treatment was performed in the same procedure and method as in Test Example 4.2, and the treated water T-CN was measured.

(Test Examples 4.4 to 4.17)
In Test Examples 4.4 to 4.17, sodium thiosulfate was not used in step (A), the amount of H ₂ O ₂ added in step (A), and the H ₂ O ₂ remover in step (B2) The treatment was carried out in the same procedure and method as in Test Example 4.1, except that the type and the amount of addition thereof and the amount of cuprous oxide added in step (C) were set to the conditions shown in Table 4. T-CN was measured. In Test Examples 4.4 to 4.10, a solution prepared by adjusting “catalase (derived from bovine liver)” (manufactured by Tokyo Chemical Industry Co., Ltd.) to 0.1% by mass with pure water was used as the H ₂ O ₂ remover. did. In Test Examples 4.11 to 4.13, powdered manganese dioxide (MnO ₂ ) was used as it was. In Test Examples 4.14 to 4.17, powdered activated carbon was mixed with pure water to adjust the concentration to 1% by mass, and a slurry in a stirring state was used.

  Table 4 shows the test conditions of Test Examples 4.1 to 4.17 and the results of the treated water T-CN.

From the results of Test Example 4, although the hydrogen peroxide remained in the reaction solution obtained after the addition and reaction of hydrogen peroxide to the water to be treated, the hydrogen peroxide removing agent (sodium sulfite, catalase, It was confirmed that the addition of manganese and activated carbon) could reduce the residual H ₂ O ₂ concentration in the reaction solution. In addition, by this, the total cyanide concentration of the treated water from the reaction solution obtained after the addition and reaction of the copper (I) compound can be sufficiently reduced, and the cyanide component can be highly removed from the water to be treated. Was confirmed.

DESCRIPTION OF SYMBOLS 10 Cyan-containing water treatment equipment 11 1st reaction tank 12 2nd reaction tank 13 Measuring device of hydrogen peroxide concentration 16 Solid-liquid separation device 17 Control unit 20 Cyan-containing water treatment equipment 21 1st reaction tank 22nd 2 reaction tank 23, 25, 27 Hydrogen peroxide concentration measuring device 24 Removal tank 26 Solid-liquid separation device

Claims (15)

A step (A) of adding hydrogen peroxide to water to be treated containing cyanide ions and an iron cyano complex to cause a reaction,
Measuring the concentration of the hydrogen peroxide remaining in the reaction solution obtained in the step (A) (B1);
A step (C) of adding a copper (I) compound to the reaction solution obtained in the step (A) to cause a reaction,
And (D) performing a solid-liquid separation treatment on the reaction solution obtained in the step (C).
The amount of the hydrogen peroxide added to the water to be treated in the step (A) is adjusted so that the value of the hydrogen peroxide concentration measured in the step (B1) becomes 10 mg-H ₂ O ₂ / L or less. A method for controlling cyanide-containing water. The amount of the hydrogen peroxide added to the water to be treated in the step (A) is determined so that the value of the hydrogen peroxide concentration measured in the step (B1) becomes 5 mg-H ₂ O ₂ / L or less. The method for treating cyan-containing water according to claim 1, wherein   The cyanide according to claim 1 or 2, wherein the hydrogen peroxide is added to the water to be treated in the step (A) while monitoring the value of the hydrogen peroxide concentration measured in the step (B1). How to treat contained water. A step (A) of adding hydrogen peroxide to water to be treated containing cyanide ions and an iron cyano complex to cause a reaction,
A step (B2) of bringing the reaction solution obtained in the step (A) into contact with a hydrogen peroxide removing agent that reduces the concentration of the hydrogen peroxide remaining in the reaction solution to cause a reaction;
A step (C) of adding a copper (I) compound to the reaction solution obtained in the step (B2) to cause a reaction,
A step (D) of subjecting the reaction solution obtained in the step (C) to a solid-liquid separation treatment.   The method for treating cyanogen-containing water according to claim 4, further comprising a step (B1) of measuring a concentration of the hydrogen peroxide remaining in the reaction solution obtained in the step (A).   The method for treating cyanogen-containing water according to claim 4 or 5, further comprising a step (B3) of measuring a concentration of the hydrogen peroxide remaining in the reaction solution obtained in the step (B2).   The method for treating cyanogen-containing water according to any one of claims 4 to 6, wherein the hydrogen peroxide removing agent includes one or both of a reducing agent for hydrogen peroxide and a catalyst for decomposing hydrogen peroxide. In the step (A), the cyanide ion in the water to be treated is decomposed by the hydrogen peroxide,
In the step (C), the copper (I) compound generates a hardly soluble iron cyano complex in the reaction solution obtained in the step (C);
The method of treating cyan-containing water according to any one of claims 1 to 7, wherein, in the step (D), the hardly soluble material is separated and removed. The water to be treated is a wastewater cleaning wastewater that has been subjected to a solid-liquid separation treatment for removing the suspended substances from the dust collected water obtained by performing a wet dust collection treatment on the exhaust gas containing the suspended substances. Yes,
A step (E) of performing one or both of a concentration treatment and a dehydration treatment on the slurry containing the solid content separated from the liquid component in the step (D);
The method according to any one of claims 1 to 8, further comprising: (F) sending the separated water obtained in the step (E) to the solid-liquid separation treatment for obtaining the washing wastewater of the exhaust gas. A method for treating cyan-containing water as described in the above.   Either or both of the water to be treated to which the hydrogen peroxide is added in the step (A) and the reaction solution to which the copper (I) compound is added in the step (C) The method for treating cyan-containing water according to any one of claims 1 to 9, further comprising adding a reducing agent.   The treatment of cyan-containing water according to any one of claims 1 to 10, wherein a quaternary ammonium compound is further added to the reaction solution to which the copper (I) compound is added in the step (C). Method.   The method according to any one of claims 1 to 11, wherein the step (A) and the step (C) are performed in separate reaction tanks. The iron cyano complex contains one or both of a ferrocyanide ion and a ferricyanide ion, and [Fe (CN) ₅ (CO)] ^3- and [Fe (CN) ₄ (CO) ₂ ] ^{2. The} method for treating cyan-containing water according to any one of claims 1 to 12, comprising one or both of-. A reaction tank (a) for reacting water to be treated containing cyanide ion and iron cyano complex by adding hydrogen peroxide thereto;
A measuring device (b1) for measuring the concentration of the hydrogen peroxide remaining in the reaction solution obtained in the reaction tank (a),
A reaction tank (c) in which a copper (I) compound is added to and reacted with the reaction solution obtained in the reaction tank (a);
A solid-liquid separator (d) for solid-liquid separation of the reaction solution obtained in the reaction tank (c),
The addition amount of the hydrogen peroxide to the water to be treated in the reaction tank (a) is such that the value of the hydrogen peroxide concentration measured by the measuring device (b1) is 10 mg-H ₂ O ₂ / L or less. A control unit for controlling the amount;
A facility for treating cyanide-containing water, comprising: A reaction tank (a) for reacting water to be treated containing cyanide ion and iron cyano complex by adding hydrogen peroxide thereto;
A removing tank (b2) for adding and reacting a hydrogen peroxide removing agent for reducing the concentration of the hydrogen peroxide remaining in the reaction solution obtained in the reaction tank (a),
A reaction tank (c) in which a copper (I) compound is added to and reacted with the reaction solution obtained in the removal tank (b2);
A solid-liquid separator (d) for solid-liquid separation of the reaction solution obtained in the reaction tank (c),
A facility for treating cyanide-containing water, comprising:

Images