WO2017073177A1 - Method for treating cyanide complex-containing wastewater and treating agent for use therein - Google Patents

Abstract

Provided is a method for treating cyanide complex-containing wastewater, the method comprising adding, to cyanide complex-containing wastewater, a mixture of a cuprous compound and hydrogen peroxide under pH 6-9 conditions, or a mixture of a cupric compound and hydrogen peroxide under pH 6-8 conditions, to thereby treat the cyanide complex contained in the wastewater.

Description

Method of treating complex cyanide-containing wastewater and treating agent used therefor

The present invention relates to a method for treating complex cyanide-containing wastewater that can efficiently remove complex cyanide in wastewater from a complex cyanide-containing wastewater by a simple operation in a safe and inexpensive manner, and a treating agent for complex cyanide-containing wastewater used therefor.
In the present invention, cyan contained in waste water in various forms, that is, among difficult-to-decompose cyan complex, easily-decomposable cyan complex and cyanide ion, particularly easily-decomposable and easily-decomposable cyan complex (complex cyan) is simplified. Can be processed with simple operations.

Cyan has a strong negative impact on ecosystems, and cyanide-containing wastewater (also referred to as “cyan wastewater”) cannot be released directly into nature. Cyan drainage standards are established based on the Water Pollution Control Law. Cyan removal processing is performed so as to satisfy this standard (1 mg / L or less). Further, depending on the region, an additional drainage standard that is lower than the above-mentioned drainage standard value is set by regulations.
Cyan is present in the wastewater in three forms of a hardly-decomposable cyanide complex, an easily-decomposable cyanide complex, and a cyanide ion, although there are some contents due to the origin of the wastewater.

Various methods have been proposed and put to practical use for removing cyan from waste water containing cyan, and all have their advantages and disadvantages, and are used properly according to the state of waste water.
For example, (1) alkaline chlorine method in which cyanide-containing wastewater is adjusted to alkalinity and then injected with chlorine to oxidatively decompose cyanide. (2) cyanide is oxidized and decomposed into nitrogen gas and bicarbonate with strong ozone oxidizing power. (3) “Oxidative decomposition method” such as electrolytic oxidation method (electrolysis method) in which cyanide is electrolyzed and an oxidation reaction is performed using an insoluble electrode; (4) In cyanide-containing wastewater, As a supply compound of iron ions, for example, ferrous sulfate is added to produce a poorly soluble ferri / ferrocyanide, and this is precipitated and removed. (5) Addition of zinc chloride and a reducing agent (7) “insoluble complex method” such as zinc white method for precipitating and removing insoluble complex and (6) reducing copper salt method for adding divalent copper salt and reducing agent and precipitating and removing generated insoluble complex; Microbes acclimated to cyanide (Biodegradation method) that decomposes cyanide into (decomposing bacteria); (8) Heat that keeps cyanate-containing wastewater at a high temperature to hydrolyze cyanide compounds into ammonia and formic acid, and precipitates coexisting heavy metals as simple substances or oxides In addition to the hydrolysis method and (9) cyanide decomposition, there are “hydrothermal reaction” such as wet oxidation method that also oxidatively decomposes organic pollutants.

For example, in Japanese Patent Application Laid-Open No. 05-68979 (Patent Document 1), an aqueous solution containing a cyanide and / or cyano complex which may contain a solid is prepared by using Mn, Co, Ni, Cu, Cd, Zn. By using at least one equivalent of peroxide compound per equivalent of cyanide in the presence of heavy metal compounds from the series, the solution is oxidatively treated with the peroxide compound to give a pH value of 8-12. And from a series of alkali metal perborate and alkaline earth metal perborate, alkali metal percarbonate and alkaline earth metal peroxide in a detoxifying process at a temperature from the freezing point of the solution to 80 ° C. One or more peroxide compounds are used, in which case the peroxide compounds should be detoxified in solid form or dissolved or suspended in water. Characterized in that it is added to the solution, or in this solution, the remaining forming components from the series of hydrogen peroxide and metaborate ions, alkali metal ions and alkaline earth metal ions are formed in situ. , A method for detoxifying an aqueous solution containing cyanide and / or cyano complex is disclosed.

In addition, the applicant of the present invention disclosed in Japanese Patent Application Laid-Open No. 2013-146696 (Patent Document 2) that a cyanine-containing wastewater has an amount of a manganese compound capable of removing cyan contained in the wastewater, and a copper compound and / or aluminum. After the addition of the compound, the wastewater is treated under a pH of 6 to 9.5, and the produced water-insoluble salt is removed from the wastewater to remove cyanide in the wastewater. A method is disclosed.

Japanese Patent Laid-Open No. 05-68979 JP 2013-146696 A

However, the above-described prior art requires complicated processes and operations, and accordingly, a plurality of reaction vessels may be required. In addition, complex cyanide-containing wastewater does not have a sufficient effect of removing complex cyanide, and the cyanide concentration of the wastewater after treatment satisfies the drainage standard (1 mg / L or less), and further satisfies the additional drainage standard in consideration of environmental impact. There was a problem that the concentration could not be made and the treated wastewater could not be discharged into sewage as it was.

In addition, the Water Pollution Control Law also establishes heavy metal drainage standards and, like cyan, can only be discharged into sewage or other wastewater if it is below the standards. For example, the copper drainage standard (copper content) is 3 mg / L or less, and in the above prior art, when a copper compound is used, the copper content in the treated wastewater also needs to be below the drainage standard. .
Furthermore, based on the Water Pollution Control Law, the drainage standard for hydrogen ion concentration (pH) is set at 5.0 to 9.0 for sea areas and 5.8 to 8.6 outside sea areas. In the above prior art, when the pH of wastewater is adjusted to acidic or alkaline, neutralization treatment is required to adjust not only the cyanide concentration of wastewater but also the pH within the drainage standard range before discharging into sewage etc. Sometimes it becomes.

It is an object of the present invention to provide a method for treating complex cyanide-containing wastewater that can efficiently remove complex cyanide in wastewater from a complex cyanide-containing wastewater safely and inexpensively by a simple operation and a treatment agent used therefor. To do.

The inventors of the present invention have made extensive studies to solve the above problems, and as a result, the complex cyanide-containing wastewater coexists with a cuprous compound and hydrogen peroxide under the conditions of pH 6 to 9, or pH 6 It has been found that cyanide in waste water can be efficiently treated by coexisting a cupric compound and hydrogen peroxide under the conditions of ˜8, and the present invention has been completed.

Thus, according to the present invention, the complex cyanide-containing wastewater is allowed to coexist with the cuprous compound and hydrogen peroxide under the condition of pH 6-9, or the cupric compound and hydrogen peroxide under the condition of pH 6-8. There is provided a method for treating complex cyanide-containing wastewater comprising coexisting hydrogen peroxide and treating complex cyanide in the wastewater.

Moreover, according to the present invention, there is provided a treating agent for complex cyanine-containing wastewater used in the above-described method for treating complex cyanine-containing wastewater,
The treating agent comprises a complex containing an aqueous hydrogen peroxide solution or an aqueous hydrogen peroxide supply compound as hydrogen peroxide, and an aqueous solution of a cuprous or cupric compound as a cuprous compound or cupric compound. A treatment agent for cyanine-containing wastewater is provided.

According to the present invention, it is possible to provide a method for treating complex cyanide-containing wastewater that can efficiently remove complex cyanide in wastewater from a complex cyanide-containing wastewater with a simple operation, safely and inexpensively, and a treatment agent used therefor. it can.
Therefore, even if the wastewater treated by the method of the present invention is released into nature as it is, the influence on the environment can be very small, and therefore the method of the present invention is extremely useful industrially.

Further, the complex cyanide-containing wastewater treatment method of the present invention exhibits the above-described effect more when any one of the following conditions is satisfied.
(1) The complex cyanide concentration and the total cyan concentration in the complex cyanine-containing wastewater are 1 mg / L or more and 10 mg / L or less, respectively.
(2) The cuprous compound or the cupric compound has a molar concentration of all cyans including complex cyan as 1, and is equivalent to 0.05 equivalent mole or more in terms of copper, and hydrogen peroxide includes complex cyanide. It is added to the complex cyanide-containing waste water so that the molar concentration of all cyan is 1, and the concentration is 1 equimolar or more.
(3) The cuprous compound is a compound selected from cuprous chloride, cuprous fluoride, cuprous bromide, cuprous iodide, cuprous nitrate and cuprous sulfate, The dicopper compound is a compound selected from cupric chloride, cupric fluoride, cupric bromide, cupric iodide, cupric nitrate and cupric sulfate.
(4) The total cyan concentration in the complex cyanide-containing wastewater after treatment is 1 mg / L or less.

(1) Complex cyanide-containing wastewater treatment method The complex cyanide-containing wastewater treatment method of the present invention is a complex cyanide-containing wastewater, wherein the wastewater is allowed to coexist with a cuprous compound and hydrogen peroxide at pH 6-9. Alternatively, the complex cyanide in the wastewater is treated by coexisting a cupric compound and hydrogen peroxide under conditions of pH 6-8.

In the present invention, “a coexistence of a cuprous compound or cupric compound and hydrogen peroxide” means that a cuprous compound or cupric compound (hereinafter, both are also referred to as “copper compound”) and excess. This means that hydrogen oxide is present in complex cyanide-containing wastewater. The coexistence may be by addition of a copper compound and hydrogen peroxide, or by generation in complex cyanide-containing wastewater, as will be described later. In the case of addition, the order is not particularly limited. It may be.

The mechanism (action mechanism) for removing complex cyanide in the method for treating wastewater containing complex cyanide of the present invention is not clear, but the inventors of the present invention consider as follows.
In the method of Patent Document 1 described above, a peroxide compound such as hydrogen peroxide is added in the presence of a heavy metal containing copper to detoxify a cyan-containing aqueous solution. It is said that a detoxification (removal) effect can be obtained. On the other hand, according to the results of test examples to be described later, the removal efficiency of complex cyanide at pH 10 is inferior to that at pH 7-9.
That is, the complex cyanide-containing wastewater treatment method of the present invention has a pH condition that exhibits an excellent complex cyanide removal effect, which tends to be contrary to Patent Document 1, and in this respect, the mechanism differs from Patent Document 1. It is considered a thing.
Further, in the method of Patent Document 1, the cyan concentration in the cyan-containing aqueous solution to be treated is not particularly defined, and in this embodiment, a cyan-containing aqueous solution having a cyan concentration of 100 ppm (mg / L) is used. On the other hand, the method for treating complex cyanide-containing wastewater of the present invention is intended to treat complex cyanine-containing wastewater that has been conventionally difficult to remove, and has demonstrated its effect. This is probably due to a different mechanism.

(Waste water containing complex cyanide)
The complex cyanide-containing wastewater to be treated in the present invention is not particularly limited as long as it is wastewater containing complex cyanide.
A remarkable cyan removal effect is obtained when the complex cyanide concentration and the total cyan concentration in the complex cyanine-containing wastewater are 1 mg / L or more and 10 mg / L or less, respectively.
Examples of complex cyanide-containing wastewater include complex cyanides including metal cyanide, cyanide, cyanide complex, and cyano complex ion discharged from steel factories, chemical factories, plating factories, coke factories, metal surface treatment factories, and the like. Examples of such wastewater include complex cyanide-containing wastewater discharged in a treatment process of radioactively contaminated water, and complex cyanine-containing wastewater discharged from a soil treatment apparatus.

(Copper compound and cupric compound)
The copper compound used in the present invention is not particularly limited as long as it is a cuprous compound and a cupric compound that are soluble or easily dispersed in water and can form monovalent or divalent copper ions in water. Either an organic copper compound or an inorganic copper compound may be used.
Examples of the organic copper compound include cupric compounds selected from cupric acetate, cupric benzoate, cupric citrate, copper naphthenate, and cupric oleate.

Examples of the inorganic copper compound include cuprous chloride, cuprous fluoride, cuprous bromide, cuprous iodide, cuprous nitrate and cuprous sulfate, and chloride. Examples include cupric compounds selected from cupric, cupric fluoride, cupric bromide, cupric iodide, cupric nitrate, and cupric sulfate.
Since the organic copper compound may increase the COD in the complex cyanide-containing wastewater after the treatment, among the above copper compounds, the inorganic copper compound is preferable, and the effect of removing complex cyanide and the treatment cost of the complex cyanine-containing wastewater are preferred. Inorganic cuprous compounds are more preferable, cuprous chloride and cuprous sulfate are more preferable, and cuprous chloride is particularly preferable.

The above copper compound may be treated with a metal scavenger so as to have a desired copper equivalent concentration when added to the complex cyanide-containing wastewater. Further, it may be used after diluting or dissolving with water such as industrial water.
Here, as a metal scavenger, a liquid chelating agent etc. are mentioned, for example.
Further, when the cuprous compound is a cuprous salt, a cuprous salt solution containing hydrogen chloride water, an aqueous alkali metal halide solution or ethanol as a solvent is used to stabilize the cuprous salt. It is preferable from the point.
In the method of the present invention, as the cuprous compound, the cupric compound is added to the complex cyanide-containing wastewater together with the reducing agent, or the cupric compound is added to the reducing complex cyanide-containing wastewater, A cuprous ion supply compound produced by reducing a cupric compound is included.
Here, examples of the reducing agent include sulfites, divalent iron salts, hydrazine, and the like.

(hydrogen peroxide)
Examples of the hydrogen peroxide used in the present invention include a hydrogen peroxide aqueous solution having a concentration of 3 to 60%, which is commercially available mainly for industrial use.
In addition, hydrogen peroxide generated from a hydrogen peroxide supply compound (also referred to as a “hydrogen peroxide generator”), or hydrogen peroxide generated by electrolysis of water or an alkaline solution can be used.
Examples of the hydrogen peroxide supplying compound include inorganic peracids such as percarbonate, perboric acid and peroxysulfuric acid capable of releasing hydrogen peroxide in water, organic peracids such as peracetic acid, and salts thereof. Examples of these salts include sodium percarbonate and sodium perborate.
The above hydrogen peroxide and hydrogen peroxide supply compound may be diluted or dissolved with water such as industrial water so that a desired hydrogen peroxide concentration is obtained upon addition.

(Drug concentration)
The concentration of the copper compound in the complex cyanide-containing wastewater may be appropriately set depending on the conditions of the wastewater, but the copper compound is generally 0.05 equivalent mole in terms of copper, where the molar concentration of all cyanide including complex cyan is 1. It is preferable to add to cyanide-containing wastewater so as to have the above concentration.
The specific copper compound concentration is, for example, 0.005, 0.01, 0.02, 0.03, 0.04 in terms of copper (equal mole), where the molar concentration of all cyan including complex cyan is 1. 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0 .8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 It is.
A more preferable copper compound is 0.1 to 2 equimolar, more preferably 0.2 to 1 equimolar in terms of copper, where the molar concentration of all cyan including complex cyan is 1.

The concentration of hydrogen peroxide in the complex cyanide-containing wastewater may be appropriately set depending on the conditions of the wastewater, etc., but hydrogen peroxide is usually 1 in terms of hydrogen peroxide, where the molar concentration of all cyan including complex cyan is 1. It is preferable to add to cyanide-containing wastewater so as to have a concentration of equimolar or higher.
If hydrogen peroxide is less than 1 mole, assuming that the molar concentration of all cyan including complex cyan is 1, sufficient cyan removal effect may not be obtained.
The specific concentration of hydrogen peroxide is, for example, 1.0, 1.5, 2.0, 2.5, in terms of hydrogen peroxide (equivalent mole), where the molar concentration of all cyan including complex cyan is 1. 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9. 0, 9.5, and 10.0.
More preferable hydrogen peroxide is 1 to 10 equimolar, more preferably 2 to 5 equimolar, assuming that the molar concentration of all cyan including complex cyan is 1.

(Coexistence of copper compound and hydrogen peroxide)
In the present invention, in order for the copper compound and hydrogen peroxide to coexist in the complex cyanide-containing wastewater to be treated, the aqueous solution of hydrogen peroxide or hydrogen peroxide supply compound as hydrogen peroxide in the complex cyanine-containing wastewater. And a copper compound aqueous solution as a copper compound may be added simultaneously or separately.
Here, examples of the hydrogen peroxide supply compound include the compounds exemplified in the section of (hydrogen peroxide).

As noted above, it is preferred to add the copper compound and hydrogen peroxide in the form of an aqueous solution, the concentration of which is added to the complex cyanide-containing wastewater, along with an effective amount for the total cyanide concentration in the wastewater. In consideration of the workability at the time, the reactivity between the complex cyanide and the added compound, etc. may be appropriately determined.

More specifically, the complex cyanide-containing wastewater treatment method of the present invention allows a complex cyanide-containing wastewater to coexist with a cuprous compound and hydrogen peroxide under the conditions of pH 6 to 9, or pH 6 to And a complex cyanide in the wastewater is treated by coexisting a cupric compound and hydrogen peroxide under the condition of No. 8.

It is preferable to stir the mixed solution uniformly at the time of addition of the copper compound and hydrogen peroxide and at the time of reaction of these added compounds and complex cyanate in terms of the effect of removing complex cyanide. This stirring is preferably carried out every time each drug is added.
In order to promote the reaction during stirring, the temperature of the mixed solution is preferably heated to some extent, but about 20 to 60 ° C. is sufficient.
Furthermore, the time required for the reaction during stirring varies depending on the amount of cyanide-containing wastewater, the type and concentration of cyanide, the form of the treatment apparatus and the scale thereof, and so on, so that cyan and the added compound are in sufficient contact. Just decide. Usually, the stirring time may be 10 minutes to 6 hours, more preferably 20 to 60 minutes.

In the method of the present invention, after the addition of the cuprous compound and hydrogen peroxide, the complex cyanide-containing wastewater is subjected to the condition of pH 6 to 9, or after the addition of the cupric compound and hydrogen peroxide, If water-insoluble salts produced under the conditions of pH 6-8 of cyan-containing wastewater are present, they may be removed.
When the pH of the complex cyanine-containing wastewater is not in the range of 6-9 or 6-8, the pH of the treated wastewater may be adjusted to the above range by a known method.
For pH adjustment, an acid or alkali that does not interfere with the reaction in the treatment of the present invention, such as sulfuric acid or sodium hydroxide, may be added to the treatment wastewater.

In the method for treating cyanide-containing wastewater of the present invention, known agents such as an antifoaming agent, a polymer flocculant, a rust inhibitor, a corrosion inhibitor, a scale dispersant, and a slime control agent are used within the range not inhibiting the effects of the present invention. May be used in combination.

For removing the water-insoluble salt, a known apparatus such as a thickener and a turbidity sedimentation basin can be used, and a surfactant may be added to the treated wastewater as long as the effects of the present invention are not hindered.

(Cyanide-containing wastewater after treatment)
Through the above treatment, the total cyan concentration (mg / L) including complex cyan before treatment, and further the copper concentration generated by the addition of chemicals to a concentration that is less than the drainage standard value and can meet the drainage standard by adding it to the drainage standard value. It can be remarkably reduced, and the treated wastewater can be discharged or reused as it is to sewage without neutralization.
Specifically, the total cyan concentration including complex cyanide can be reduced to 1.5 mg / L or less, preferably 1 mg / L or less, and the copper concentration is reduced to 3 mg / L or less, preferably 1 mg / L or less. be able to.

(2) Treatment agent for cyanide-containing wastewater According to the present invention, an aqueous solution of hydrogen peroxide or hydrogen peroxide supply compound as hydrogen peroxide, and a cuprous compound or cuprous compound or cupric compound or An agent for treating complex cyanide-containing wastewater, comprising an aqueous solution of a cupric compound is provided.

The present invention will be specifically described with reference to test examples, but the present invention is not limited to these test examples.

(Test Example 1) All-Cyan Removal Effect Confirmation Test In Test Example 1, cyan-containing water having the water quality shown in Table 1 prepared as follows was used as cyan-containing waste water.
Cyan-containing water was prepared using an aqueous potassium ferrocyanide solution, an aqueous potassium cyanide solution, an aqueous calcium chloride dihydrate solution, an aqueous sodium chloride solution, an aqueous sodium sulfate solution, and an aqueous sodium hydrogen carbonate solution.

In Test Example 1, the following aqueous solution was used as an additive agent.
Cuprous aqueous solution: 70% of 35% hydrochloric acid (special grade reagent, manufactured by Kishida Chemical Co., Ltd.), cuprous chloride 20 g (special grade reagent, manufactured by Kishida Chemical Co., Ltd.) and 10 g of water are dissolved and used. Cupric aqueous solution: cupric sulfate pentahydrate (reagent, manufactured by Kishida Chemical Co., Ltd. ) dissolved in a ratio of 19.6 g and water 80.4 g, and using the prepared aqueous solution Hydrogen peroxide aqueous solution: hydrogen peroxide (30%, reagent, manufactured by Kishida Chemical Co., Ltd.)

Dispense 200 mL of cyanide-containing wastewater into a 200 mL beaker, add an inorganic copper compound aqueous solution and a hydrogen peroxide aqueous solution to the concentrations shown in Table 2, respectively, and then add a sulfuric acid aqueous solution (2%) or sodium hydroxide. An aqueous solution (2% or 24%) was added to adjust the pH of the test water to the value shown in Table 9 to obtain each test water.
In Example 9, sodium bisulfite was added to the cyan waste water as a reducing agent so as to be 100 mg / L.
Next, the obtained test water was used with a stirrer (manufactured by Miyamoto Seisakusho Co., Ltd., jar tester (sample water agglomeration reactor), model: MJS-6, stirrer blade shape: two blades, stirrer blade maximum diameter 60 mm). And stirred for 60 minutes at 120 rpm.
After stirring, the test water was No. It filtered with 5C filter paper, the total cyan density | concentration (T-CN) in filtered water was measured based on JISK0102, 38 terms, and the cyan removal effect in each test water was evaluated.
In this test, a blank test (Comparative Example 1) in which an inorganic copper compound aqueous solution and a hydrogen peroxide aqueous solution were not added was simultaneously performed.
The obtained results are shown in Table 2 together with the additive compound, its addition amount, and the pH of the test water.

From the test results shown in Table 2, in Examples 1 to 9, in which a water-insoluble salt produced under conditions of pH 6 to 9 was removed by coexisting a cyanide-containing wastewater containing complex cyanide with a copper compound and hydrogen peroxide, It can be seen that cyan can be efficiently removed from wastewater.
Specifically, the following can be understood.
・ Combination treatment of cuprous compound and hydrogen peroxide at pH 6-9 (Examples 1, 3, 5, 6 and 8), Combination treatment of cupric compound and hydrogen peroxide at pH 7-8 (Examples) 2, 4, 7 and 9) have sufficient cyan removal effect. Even for waste water containing complex cyanide, the first copper compound or the second copper compound is 1 equimolar or less with respect to the total cyan concentration. It has a sufficient cyan removal effect. On the other hand, the treatment using only the cuprous compound at pH 7 (Comparative Example 2), the treatment using only the cupric compound (Comparative Example 3), and the second treatment at pH 8. In the treatment using only the monocopper compound (Comparative Example 5), the treatment using only the cupric compound (Comparative Example 6), and the treatment using only hydrogen peroxide at pH 7 (Comparative Example 4), the amount of the drug added Insufficient No effective cyan removal effect ・ Combination treatment of cupric compound and hydrogen peroxide at pH 9 (Comparative Example 7) assuming Patent Document 1; Combined use of cuprous compound and hydrogen peroxide at pH 10 In the treatment (Comparative Example 8) and in the combined treatment of the cupric compound and hydrogen peroxide (Comparative Example 9), it was assumed that an effect of removing cyan was obtained, but in the waste water containing complex cyan, the effect was obtained. Is not enough

Claims (6)

1. In the complex cyanide-containing wastewater, the wastewater is allowed to coexist with a cuprous compound and hydrogen peroxide under the condition of pH 6 to 9, or the cupric compound and hydrogen peroxide are allowed to coexist under the condition of pH 6 to 8, A method for treating wastewater containing complex cyanide comprising treating complex cyanide in wastewater.
2. The method for treating complex cyanide-containing wastewater according to claim 1, wherein the complex cyanide concentration and the total cyan concentration in the complex cyanide-containing wastewater are 1 mg / L or more and 10 mg / L or less, respectively.
3. The cuprous compound or the cupric compound has a molar concentration of all cyans including the complex cyan of 1 and the concentration of 0.05 equivalent mole or more in terms of copper, and the hydrogen peroxide contains the complex cyanide. The method for treating complex cyanide-containing wastewater according to claim 1, wherein the complex cyanide-containing wastewater is added to the complex cyanide-containing wastewater so as to have a concentration of 1 equimolar or more with a molar concentration of all cyan contained in the mixture.
4. The cuprous compound is a compound selected from cuprous chloride, cuprous fluoride, cuprous bromide, cuprous iodide, cuprous nitrate and cuprous sulfate, and the cupric The complex cyanide-containing compound according to claim 1, wherein the compound is a compound selected from cupric chloride, cupric fluoride, cupric bromide, cupric iodide, cupric nitrate and cupric sulfate. Wastewater treatment method.
5. The method for treating complex cyanide-containing wastewater according to claim 1, wherein the total cyanide concentration in the complex-cyanide-containing wastewater after the treatment is 1 mg / L or less.
6. A treatment agent for complex cyanide-containing wastewater used in the method for treating complex cyanide-containing wastewater according to claim 1,
   The treating agent comprises a complex containing an aqueous hydrogen peroxide solution or an aqueous hydrogen peroxide supply compound as hydrogen peroxide, and an aqueous solution of a cuprous or cupric compound as a cuprous compound or cupric compound. Treatment agent for cyanide-containing wastewater.