KR20210136736A - Plating wastewater purification treatment system using metal oxidation water - Google Patents

Abstract

The present invention relates to a device and a method for purifying plating wastewater using metal oxide water, and more specifically, to a device and a method for treating cyanide contained in plating wastewater through a one-step reaction.

Description

Equipment for purification and treatment of plating wastewater using metal oxide water

The present invention relates to an apparatus and method for purifying plating wastewater, and more particularly, to an apparatus and method for treating cyanide contained in plating wastewater using metal oxide water through a one-step reaction.

Plating wastewater generated in the plating process contains a large amount of harmful heavy metals such as chromium and cyanide, and in the case of zinc plating, a large amount of ammonia is also generated.

In this regard, FIG. 1 shows a treatment process using a conventional plating wastewater purification apparatus. Referring to FIG. 1, in the conventional purification treatment apparatus for plating wastewater, first, the plating wastewater is collected in a water collecting tank 1, and then H ₂ SO ₄ or NaOH is added according to the properties of the wastewater in the pH adjusting tank 13 to adjust the pH. is adjusted to 2-3. _{Thereafter, NaHSO 3} is added in the chromium (Cr) treatment tank 17 to reduce ^{highly toxic Cr 6+} to non-toxic Cr ^{3+ .} Then, in the heavy metal treatment tank 27, NaOH, Ca(OH) _{2 ,} etc. are used to precipitate and remove heavy metals such as Cu and Zn and fluorine (F) by adding NaSH while adjusting the pH to 8 to 9. Thereafter, the pH is adjusted to 11 in the pH adjusting tank 32 , and NaOCl is added in the cyan (CN) primary treatment tank 34 to oxidize CN to CNO. Then, _{the pH is adjusted to 8 using H 2} SO ₄ in the pH adjusting tank 36, and NaOCl is added in the cyan (CN) secondary treatment tank 38 to decompose _{CNO into CO 2} and N _{2 for treatment} do. Then, after adjusting the pH to neutral in the pH adjusting tank 42, _{the COD is lowered while nitrifying ammonia to NO 3} through the biological treatment nitrification process in the nitrification tank 45, and then the denitrification tank 47 through an anaerobic tank operation The plating wastewater is discharged by denitrifying and treating _{NO 3} with N _{2 .}

In such conventional plating wastewater, a large amount of chemicals is consumed for pH adjustment, and when the pH is adjusted to 10 or more, chromium may be re-eluted again. Instability of efficiency may be caused. In addition, when the wastewater contains a large amount of ammonia, since NaOCl input for cyanide (CN) treatment reacts with ammonia, there is a problem that the input amount of NaOCl increases rapidly, resulting in a rapid increase in drug cost. In addition, the cyan (CN) treatment is processed over two steps, and the process is inefficient because the pH range required for each treatment is different.

Therefore, the present inventors have been studying to solve the above problems, if the cyanide (CN) is treated using metal oxidation water, it is possible to treat cyan through a one-step reaction, and the metal oxidation number is cyan compared to ammonia. It was found that (CN) can be selectively treated, thereby completing the present invention.

In this regard, Korean Patent Registration No. 10-0829798 discloses a plating wastewater treatment method using a vacuum evaporation method.

The present invention has been devised to solve the above-described problem, and an embodiment of the present invention provides an apparatus for purifying and treating plating wastewater using metal oxide water.

In addition, another embodiment of the present invention provides a method for purifying plating wastewater using metal oxide water.

However, the technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned are clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. it could be

As a technical means for achieving the above-described technical problem, an aspect of the present invention is

a chromium treatment unit 200 for reducing chromium contained in the plating wastewater; a cyanide treatment unit 400 for decomposing cyanide contained in the chromium-reduced plating wastewater; and an ammonia treatment unit 500 for nitrifying and denitrifying ammonia contained in the plating wastewater in which the cyanide has been decomposed, wherein the decomposition treatment of cyanide is performed by introducing metal oxidation water into the plating wastewater. It provides a purification treatment apparatus 101 of the plating wastewater to perform.

The metal oxidation number may include a compound represented by the following formula (1).

[Formula 1]

M1 _x M2 _y O ₄

In Formula 1,

M1 and M2 are each independently H, Na, K, Fe, Zn, Sn, Cu, Pb, Sb or Al, and x and y are each independently an integer of 1 or more depending on the combination of the compounds.

The metal oxidation water may be to selectively decompose cyanide compared to ammonia contained in the plating wastewater.

The amount of the metal oxide water added may be 0.1 parts by weight to 5 parts by weight based on 100 parts by weight of the plating wastewater.

The decomposition treatment of cyanide may be performed in the range of pH 4 to pH 6.

The metal oxide water may be reduced to a metal hydroxide after the decomposition treatment of cyanide, and the metal hydroxide may be to precipitate heavy metals contained in the plating wastewater.

The chrome processing unit 200 , the cyanide processing unit 400 , and the ammonia processing unit 500 may each include pH adjusting tanks 230 , 420 , and 520 for adjusting the pH of the plating wastewater.

The plating wastewater purification apparatus 101 may further include a heavy metal treatment unit 300 between the chrome treatment unit 200 and the cyan treatment unit 400 for precipitating heavy metals contained in the plating wastewater in which the chromium has been reduced. have.

In addition, another aspect of the present invention,

reducing the chromium contained in the plating wastewater; decomposing cyanide contained in the chromium-reduced plating wastewater; and nitrifying and denitrifying ammonia contained in the plating wastewater in which the cyanide has been decomposed, wherein the decomposition treatment of cyanide is performed by introducing metal oxidation water into the plating wastewater. A method for purifying and treating plating wastewater is provided.

According to an embodiment of the present invention, if the plating wastewater is purified using the plating wastewater purification apparatus, cyan (CN) contained in the plating wastewater can be treated in a one-step reaction using metal oxide water. Compared to the conventional process of treating cyan in two steps, the process can be shortened. In addition, when treating cyan in the conventional two-step process, a large amount of chemicals were added to adjust the pH required for each treatment process. Chemical cost for pH adjustment can be reduced.

In addition, since the metal oxide water can selectively treat cyan compared to ammonia contained in the plating wastewater, process efficiency can be increased, and the reduced metal hydroxide after decomposition treatment of cyan has the function of a precipitate for precipitating heavy metals. The process of the conventionally used heavy metal processing unit may be omitted.

It should be understood that the effects of the present invention are not limited to the above-described effects, and include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a schematic diagram showing a purification treatment process of plating wastewater according to the prior art.
2 is a schematic diagram showing a purification treatment process of plating wastewater according to an embodiment of the present invention.
3 is a schematic diagram showing a purification treatment process of plating wastewater according to another embodiment of the present invention.
4 is a graph showing the reaction rate constant of cyanide and ammonia according to the pH of the metal oxide water according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail. However, the present invention may be embodied in various different forms, and the present invention is not limited by the embodiments described herein, and the present invention is only defined by the claims to be described later.

In addition, the terminology used in the present invention is only used to describe specific embodiments, and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the entire specification of the present invention, 'including' any component means that other components may be further included, rather than excluding other components, unless otherwise stated.

The first aspect of the present application is

a chromium treatment unit 200 for reducing chromium contained in the plating wastewater; a cyanide treatment unit 400 for decomposing cyanide contained in the chromium-reduced plating wastewater; and an ammonia treatment unit 500 for nitrifying and denitrifying ammonia contained in the plating wastewater in which the cyanide has been decomposed, wherein the decomposition treatment of cyanide is performed by introducing metal oxidation water into the plating wastewater. It provides a purification treatment apparatus 101 of the plating wastewater to perform.

Hereinafter, the purification and treatment apparatus 101 for plating wastewater according to the first aspect of the present application will be described in detail with reference to FIG. 1, which is a prior art, and FIGS. do. At this time, FIG. 2 shows an apparatus 101 for purifying plating wastewater that does not include the heavy metal treatment unit 300 according to the present invention, and FIG. 3 is an apparatus 101 for purifying plating wastewater including the heavy metal treatment unit 300 according to the present invention. indicates

In one embodiment of the present application, the apparatus 101 for purifying the plating wastewater may include a water collecting tank 110 for collecting the plating wastewater. The water collecting tank 110 serves as a chamber for collecting the plating wastewater and transporting it to the subsequent process. The shape or size is not limited, and an appropriate size can be selected and applied according to the content of the plating wastewater to be purified. it could be

In one embodiment of the present application, the apparatus 101 for purifying the plating wastewater may include a chromium treatment unit 200 for reducing chromium contained in the plating wastewater. The chrome treatment unit 200 may serve to perform a process of reducing the ^{highly toxic Cr 6+} contained in the plating wastewater to the non-toxic Cr ^{3+ .}

In one embodiment of the present application, the chrome treatment unit 200 may include a chrome treatment pH adjusting tank 230 and a chrome treatment tank 270 , and the plating wastewater collected in the water collecting tank 110 is treated with the chrome. It may be transferred to the pH adjusting tank 230 to adjust the pH, and the pH-adjusted plating wastewater may be transferred to the chrome treatment tank 270 to reduce ^{Cr 6+} contained in the plating wastewater to Cr ^{3+ .} Specifically, the chromium treatment pH adjusting tank 230 serves to adjust the pH of the plating wastewater to pH 2 to 3, which is an appropriate pH range for performing the reduction reaction of chromium, and is adjusted to the pH of the transferred plating wastewater. Depending on the situation, NaOH or H ₂ SO ₄ may be added to adjust the pH. The plating wastewater whose pH is adjusted to 2 to 3 in the pH adjusting tank 230 as described above is then transferred to the chrome treatment tank 270, and NaHSO ₃ is added to the chrome treatment tank 270 to add strong toxicity to Cr ⁶⁺ may be reduced to Cr ^{3+ .}

In one embodiment of the present application, the purification treatment apparatus 101 of the plating wastewater may include a cyanide treatment unit 400 for decomposing the cyanide contained in the chromium-reduced plating wastewater. The cyanide treatment unit 400 may serve to decompose cyanide contained in the plating wastewater. In this case, the cyanide may be dissolved in the form of ions in the plating wastewater, or may be dissolved in the form of a compound including a cyanide group.

In one embodiment of the present application, the cyan treatment unit 400 may include a cyanide treatment pH adjustment tank 420 and a cyanide treatment tank 440 , and plating wastewater in which chromium is reduced in the chrome treatment tank 270 . may be transferred to the cyanide treatment tank 420 to adjust the pH, and the pH-adjusted plating wastewater may be transferred to the cyanide treatment tank 440 to decompose the cyanide contained in the plating wastewater. Specifically, the cyanide treatment pH adjusting tank 420 serves to adjust the pH of the plating wastewater to pH 4 to 6, preferably pH 5, which is an appropriate pH range for decomposing cyanide, and is NaOH or H ₂ SO ₄ and the like may be added to adjust the pH. The plating wastewater whose pH is adjusted to 4 to 6, preferably to pH 5 in the pH adjusting tank 420 as described above is then transferred to the cyanide treatment tank 440, and metal oxidation water is introduced into the cyanide treatment tank 440 to It may be to decompose the cyanide.

In one embodiment of the present application, the metal oxidation number is a material in which a metal oxide is dissolved in an aqueous solution, and the metal oxidation number may include a compound represented by the following formula (1).

[Formula 1]

M1 _x M2 _y O ₄

In Formula 1, M1 and M2 are each independently H, Na, K, Fe, Zn, Sn, Cu, Pb, Sb or Al, and x and y are each independently an integer of 1 or more depending on the combination of the compound. can Preferably, in Formula 1, M1 and M2 may each independently be H, Na, K or Fe, and more preferably, the compound may be H ₂ FeO ₄ , Na ₂ FeO ₄ or K ₂ FeO ₄ . . The metal oxidation water has a _{higher reduction potential (about 2.20 eV) than an oxidizing agent such as hydrogen peroxide (H 2} O ₂ ) or ozone (O ₃ ) used in the past, so it may have a strong oxidizing power, and the strong oxidizing power as described above Based on the cyanide (CN) may be oxidized in one step as shown in Scheme 1 below.

[Scheme 1]

CN → CNO → CO ₂ + N ₂

More specifically, when the metal oxidation number is, for example, K ₂ FeO ₄ or Na ₂ FeO ₄ , it is dissolved in water to take _{the form of 2HFeO 4} ⁻ , and the oxidation reaction formula of cyan (CN) is as shown in Scheme 2 below. It may be made of a one-step reaction.

[Scheme 2]

2HFeO ₄ ^- + 2HCN + 2.5O ₂ + H ₂ O + 2OH ^- → 2Fe(OH) ₃ + 2HCO ₃ ^- + 2NO ₂ ^-

In this regard, as shown in FIG. 1 , NaOCl was used to decompose the cyan in the conventional purification treatment apparatus 1 for plating wastewater, and since the material has a low oxidizing power, the cyan primary treatment tank 34 ) in the primary oxidation of CN to CNO, and a two-step process of secondary oxidation of _{CNO to CO 2} and N _{2 in the cyan secondary treatment tank 38 was required.} However, since the plating wastewater purification apparatus 101 according to the present invention uses metal oxidized water having a strong oxidizing power to decompose cyanide, the reaction can be completed in one step. Accordingly, it is possible to reduce the amount of the pH adjuster used to adjust the pH required for the conventional primary and secondary treatment, respectively, and to simplify the process, which may be very advantageous in terms of process efficiency and cost.

In one embodiment of the present application, the metal oxidation water may be to selectively decompose cyanide compared to ammonia contained in the plating wastewater. In the case of NaOCl, which was conventionally used for decomposition treatment of cyan, there was a problem in that a large amount of NaOCl had to be added in order to decompose cyanide because of its high reactivity with ammonia in addition to cyanide. However, since the metal oxide water according to the present invention selectively decomposes cyan compared to ammonia, it may be possible to efficiently decompose cyan even when a small amount is added. In this regard, FIG. 4 is a graph showing the reaction rate constant of cyan and ammonia according to the pH of the metal oxidation water. Referring to this, the metal oxidation number has a reaction rate constant of about 1,000 times higher than that of ammonia in the range of pH 4 to 6. that can be checked That is, due to the significant difference in the reaction rate constant as described above, it may be possible to efficiently decompose cyanide compared to ammonia when the metal oxide water is added. On the other hand, the decomposition treatment removal rate of the cyanide due to the input of the metal oxide water may be about 99% or more, preferably about 99.5% or more. In addition, the ammonia removal rate due to the input of the metal-oxidized water may be less than about 50%, preferably less than about 35%.

At this time, the amount of the metal-oxidized water input may be 0.1 parts by weight to 5 parts by weight, preferably 0.1 parts by weight to 2 parts by weight, more preferably 0.1 parts by weight to 0.2 parts by weight, based on 100 parts by weight of the plating wastewater. can When the amount of the metal oxidation water input is less than 0.1 parts by weight compared to 100 parts by weight of the plating wastewater, the content of the metal oxidation water is relatively too small, so that it may not be possible to decompose all the cyanide contained in the plating wastewater, and when it exceeds 5 parts by weight It may be uneconomical because it has already exceeded the content capable of decomposing all cyanide.

In one embodiment of the present application, the metal oxide water may be reduced to metal hydroxide after the decomposition treatment of cyanide, and the metal hydroxide may be to precipitate heavy metals contained in the plating wastewater. That is, the conventional purification treatment apparatus 1 for plating wastewater includes a heavy metal treatment unit 300 that injects NaSH to precipitate and remove heavy metals contained in the plating wastewater, but the purification treatment apparatus 101 according to the present invention provides the Since the metal hydroxide serves to precipitate the heavy metal, the heavy metal processing unit 300 may not be required.

In one embodiment of the present application, the purification treatment apparatus 101 of the plating wastewater may include an ammonia treatment unit 500 that nitrifies and denitrifies ammonia contained in the plating wastewater in which the cyanide has been decomposed.

In one embodiment of the present application, the ammonia treatment unit 500 may include an ammonia treatment pH adjustment tank 520 , a nitrification tank 550 , and a denitrification tank 570 . Specifically, the plating wastewater in which cyanide has been decomposed in the cyanide processing unit 400 is transferred to the ammonia treatment pH adjusting tank 520 to adjust the pH, and the pH-adjusted plating wastewater is transferred to the nitrification tank 550, sikimyeo nitrifying the ammonia in the waste water contained in the plating NO _3, a plating waste water containing the NO ₃ is transferred to the denitrification tank 570 may be one in which the NO ₃ denitration treatment with N _2. More specifically, the ammonia treatment pH adjusting tank 520 serves to adjust the pH of the plating wastewater to pH 6 to 8, preferably pH 7, which is a pH range suitable for nitrification and denitrification treatment of ammonia, and NaOH. Alternatively, it may be to adjust the pH by adding _{H 2} SO _{4 or the like.} The plating wastewater whose pH is adjusted to 6 to 8, preferably pH 7 in the pH adjusting tank 520 as described above is then transferred to the nitrification tank 550, and through the biological treatment nitrification process in the nitrification tank 550, ammonia It may be to lower the COD of the wastewater solution while nitrifying to NO _{3 .} Thereafter, the nitrification-treated plating wastewater may be transferred to the denitrification tank 570 and discharged by denitrifying _{the NO 3} into N _{2 through an anoxic tank operation.}

In one embodiment of the present application, the purification treatment apparatus 101 of the plating wastewater includes a heavy metal treatment unit ( 300) may be further included. In this case, the heavy metal treatment unit is a place for precipitating and removing heavy metals such as Cu, Zn, Ni and F, and may include a heavy metal treatment pH adjusting tank 330 and a heavy metal treatment tank 370 . Specifically, the heavy metal treatment pH adjustment tank 330 serves to adjust the pH of the plating wastewater to pH 8 to 9, which is a pH range suitable for heavy metal precipitation treatment, by adding _{NaOH or Ca(OH) 2 , etc.} It may be to adjust the pH. The plating wastewater whose pH is adjusted to 8 to 9 in the pH adjusting tank 330 as described above is then transferred to the heavy metal treatment tank 370, and NaSH is added to the heavy metal treatment tank 370 to precipitate and remove the heavy metal. it could be

On the other hand, since the heavy metal treatment unit 300 performs a role of precipitating heavy metals in the reduced metal oxide water, that is, metal hydroxides, as described above, in the plating wastewater purification treatment apparatus 101 according to the present invention, the configuration can be omitted. it could be However, it may be necessary to use the plating wastewater containing a high content of heavy metals when purifying, in this case, a bypass pipe is installed between the chrome processing unit 200 and the cyanide processing unit 400 . to selectively operate the heavy metal processing unit 300 .

The second aspect of the present application is

reducing the chromium contained in the plating wastewater; decomposing cyanide contained in the chromium-reduced plating wastewater; and nitrifying and denitrifying ammonia contained in the plating wastewater in which the cyanide has been decomposed, wherein the decomposition treatment of cyanide is performed by introducing metal oxidation water into the plating wastewater. A method for purifying and treating plating wastewater is provided.

Although detailed descriptions of parts overlapping with the first aspect of the present application have been omitted, the contents described with respect to the first aspect of the present application may be equally applied even if the description thereof is omitted from the second aspect.

Hereinafter, the purification treatment method of the plating wastewater according to the second aspect of the present application will be described in detail step by step.

First, in one embodiment of the present application, the purification treatment method of the plating wastewater includes reducing chromium contained in the plating wastewater. The step of reducing the chromium is a step of reducing the highly ^{toxic Cr 6+} contained in the plating wastewater to the non-toxic Cr ^{3+ ,} and may be performed by adding _{NaHSO 3} at a pH of 2 to 3. In this case, the pH may be adjusted by adding _{NaOH or H 2} SO ₄ according to the pH of the plating wastewater.

Next, in one embodiment of the present application, the purification treatment method of the plating wastewater includes the step of decomposing the cyanide contained in the chromium-reduced plating wastewater. In this case, the cyanide may be dissolved in the form of ions in the plating wastewater, or may be dissolved in the form of a compound containing a cyanide group. The step of decomposing the cyanide may be performed by adding metal-oxidized water in the range of pH 4 to 6, preferably pH 5. In this case, the metal oxidation number is a material in which a metal oxide is dissolved in an aqueous solution, and the metal oxidation number may include a compound represented by the following formula (1).

[Formula 1]

M1 _x M2 _y O ₄

In Formula 1, M1 and M2 are each independently H, Na, K, Fe, Zn, Sn, Cu, Pb, Sb or Al, and x and y are each independently an integer of 1 or more depending on the combination of the compound. can Preferably, in Formula 1, M1 and M2 may each independently be H, Na, K or Fe, and more preferably, the compound may be H ₂ FeO ₄ , Na ₂ FeO ₄ or K ₂ FeO ₄ . . The metal oxidation water has a _{higher reduction potential (about 2.20 eV) than an oxidizing agent such as hydrogen peroxide (H 2} O ₂ ) or ozone (O ₃ ) used in the past, so it may have a strong oxidizing power, and the strong oxidizing power as described above Based on the cyanide (CN) may be oxidized in one step as shown in Scheme 1 below.

[Scheme 1]

CN → CNO → CO ₂ + N ₂

More specifically, when the metal oxidation number is, for example, K ₂ FeO ₄ or Na ₂ FeO ₄ , it is dissolved in water to take _{the form of 2HFeO 4} ⁻ , and the oxidation reaction formula of cyan (CN) is as shown in Scheme 2 below. It may be made of a one-step reaction.

[Scheme 2]

2HFeO ₄ ^- + 2HCN + 2.5O ₂ + H ₂ O + 2OH ^- → 2Fe(OH) ₃ + 2HCO ₃ ^- + 2NO ₂ ^-

That is, since metal oxidation water having a strong oxidizing power is used to decompose the cyanide, the reaction can be completed in one step, and thus, it may be very advantageous in terms of process efficiency and cost.

In one embodiment of the present application, the metal oxidation water may be to selectively decompose cyanide compared to ammonia contained in the plating wastewater. In the case of NaOCl, which was conventionally used for decomposition of cyan, there was a problem that a large amount of NaOCl had to be added to decompose cyan because of its high reactivity with ammonia in addition to cyan. However, since the metal oxide water according to the present invention selectively decomposes cyan compared to ammonia, it may be possible to efficiently decompose cyan even when a small amount is added. In this regard, FIG. 4 is a graph showing the reaction rate constant of cyan and ammonia according to the pH of the metal oxidation water. Referring to this, the metal oxidation number has a reaction rate constant of about 1,000 times higher than that of ammonia in the range of pH 4 to 6. that can be checked That is, due to the significant difference in the reaction rate constant as described above, it may be possible to efficiently decompose cyanide compared to ammonia when the metal oxide water is added. On the other hand, the decomposition treatment removal rate of the cyanide due to the input of the metal oxide water may be about 99% or more, preferably about 99.5% or more. In addition, the ammonia removal rate due to the input of the metal-oxidized water may be less than about 50%, preferably less than about 35%.

At this time, the amount of the metal-oxidized water input may be 0.1 parts by weight to 5 parts by weight, preferably 0.1 parts by weight to 2 parts by weight, more preferably 0.1 parts by weight to 0.2 parts by weight, based on 100 parts by weight of the plating wastewater. can When the amount of the metal oxidation water input is less than 0.1 parts by weight compared to 100 parts by weight of the plating wastewater, the content of the metal oxidation water is relatively too small, so that it may not be possible to decompose all the cyanide contained in the plating wastewater, and when it exceeds 5 parts by weight It may be uneconomical because it has already exceeded the content capable of decomposing all cyanide.

In one embodiment of the present application, the metal oxide water may be reduced to metal hydroxide after the decomposition treatment of cyanide, and the metal hydroxide may be to precipitate heavy metals contained in the plating wastewater. That is, the conventional purification treatment method of the plating wastewater includes a heavy metal treatment step of adding NaSH to precipitate and remove the heavy metal contained in the plating wastewater, but the purification treatment method according to the present invention serves to precipitate the heavy metal by the metal hydroxide. Because it does not require the heavy metal treatment step.

Next, in one embodiment of the present application, the purification treatment method of the plating wastewater includes nitrifying ammonia contained in the plating wastewater in which the cyanide is decomposed and denitrifying. The step may be carried out in the range of pH 6 to 8, preferably pH 7. Specifically, the nitrification step may be to lower the COD of the wastewater solution while nitrifying _{ammonia to NO 3} through a biological treatment nitrification process. Thereafter, the nitrification-treated plating wastewater may be discharged by denitrifying _{the NO 3} into N ₂ through an anoxic tank operation in the denitrification treatment step.

In one embodiment of the present application, the purification treatment method of the plating wastewater includes reducing chromium contained in the plating wastewater; Thereafter, the step of precipitating the heavy metal contained in the chromium-reduced plating wastewater; may further include. In this case, the step of precipitating the heavy metal is a step of precipitating and removing heavy metals such as Cu, Zn, Ni and F, and the precipitation may be performed by adding NaSH in a pH range of 8 to 9.

On the other hand, the step of precipitating the heavy metal may be omitted in the purification treatment method of the plating wastewater according to the present invention because the reduced metal oxide water, that is, the metal hydroxide, serves to precipitate the heavy metal as described above. . However, it may be necessary to use the plating wastewater containing a high content of heavy metals when purifying, and in this case, the above step may be selectively performed as necessary.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

Example 1. Purification treatment of plating wastewater using metal-oxidized water (input 0.1 wt% of metal-oxidized water)

In order to check the cyanide removal efficiency of the metal oxide water according to the present invention, metal oxide water was added to the plating waste water to perform purification treatment of the plating waste water. In this case, as the metal oxide water, _{a solution containing Na 2} FeO ₄ was used, and 0.1 wt% of the total weight of the plating wastewater was added to perform purification treatment.

Example 2. Purification treatment of plating wastewater using metal-oxidized water (input 0.15 wt% of metal-oxidized water)

The purification treatment of the plating wastewater was performed in the same manner as in Example 1, except that the content of the metal oxide water was changed to 0.15 wt%.

Example 3. Purification treatment of plating wastewater using metal-oxidized water (injection of 0.2 wt% of metal-oxidized water)

The purification treatment of the plating wastewater was performed in the same manner as in Example 1, except that the content of the metal oxide water was changed to 0.2 wt%.

Comparative Example 1. Purification treatment of plating wastewater using NaOCl (NaOCl 0.5 wt% input)

In order to confirm the cyanide removal efficiency of NaOCl according to Comparative Example, NaOCl was added to the plating wastewater to perform purification treatment of the plating wastewater. At this time, the content of the NaOCl input was 0.5 wt% based on the total weight of the plating wastewater.

Comparative Example 2. Purification treatment of plating wastewater using NaOCl (NaOCl 1.0 wt% input)

The purification treatment of the plating wastewater was performed in the same manner as in Comparative Example 1, except that the amount of NaOCl input was changed to 1.0 wt%.

Comparative Example 3. Purification treatment of plating wastewater using NaOCl (NaOCl 1.5 wt% input)

The purification treatment of the plating wastewater was performed in the same manner as in Comparative Example 1, except that the content of the input NaOCl was changed to 1.5 wt%.

Experimental Example 1. Analysis of purification treatment results of plating wastewater according to the input content of metal oxide water

The components of the plating wastewater purified through Examples 1 to 3 were analyzed and shown in Table 1 below.

[Table 1]

As shown in Table 1 above, as a result of performing purification treatment of plating wastewater using the metal oxide water of the present invention, cyanide (CN) contained in the plating wastewater was 124.0 mg/L to 0.8 mg/L and 0.6 mg/L, respectively. and 0.2 mg/L, it was confirmed that about 99% or more of the decomposition treatment was carried out. On the other hand, ammonia (NH ₃ -N) contained in the plating wastewater decreased from 280.0 mg/L to 230.0 mg/L, 190.0 mg/L, and 160.0 mg/L, respectively, confirming that the removal rate was relatively low compared to cyanide. . Through this, it was confirmed that the metal-oxidized water selectively decomposed cyan compared to ammonia. However, as the content of the metal oxide water increased, it was confirmed that the removal rate of ammonia as well as the removal rate of cyan increased. could

On the other hand, it was confirmed that the content of Cu and Zn contained in the plating wastewater was also greatly reduced, which is because the metal hydroxide produced after the metal oxide water decomposed cyanide acts as a precipitate of heavy metal, so the content is decreased. was analyzed to decrease.

Experimental Example 2. Analysis of purification treatment results of plating wastewater according to metal oxide water or NaOCl input

In order to compare the purification treatment result of the plating wastewater to which the metal oxide water was added and the purification treatment result of the plating wastewater to which NaOCl was added, the components of the plating wastewater purified through Example 1 and Comparative Examples 1 to 3 were analyzed and the following Table 2 shows.

[Table 2]

As shown in Table 2, as a result of performing the purification treatment of the plating wastewater using the metal oxide water of the present invention, the cyanide (CN) contained in the plating wastewater decreased from 124.0 mg/L to 0.8 mg/L, which was about 99% It was confirmed that the decomposition process was abnormal. On the other hand, as a result of performing purification treatment of the plating wastewater using NaOCl according to the comparative example, the cyanide contained in the plating wastewater decreased from 124.0 mg/L to 110 mg/L, 90 mg/L and 60 mg/L, respectively. Compared to Example 1, it was confirmed that the decomposition treatment of cyan was not performed well. It was analyzed that this was because the NaOCl was used to remove ammonia, and as shown in Table 2 above, the ammonia removal rate was low in Example 1, but it was confirmed that the ammonia removal rate was high in Comparative Examples 1 to 3 . That is, the metal oxide number compared to the NaOCl was analyzed to be more efficient in the cyanide treatment because it selectively decomposes cyan.

1, 101: purification and treatment equipment for plating wastewater
2, 110: water tank
10, 200: chrome processing unit
13, 230: chromium treatment pH adjustment tank
17, 270: chrome treatment tank
20, 300: heavy metal processing unit
23, 330: heavy metal treatment pH adjustment tank
27, 370: heavy metal treatment tank
30, 400: cyan processing unit
32, 36, 420: cyanide treatment pH adjustment tank
34: cyan primary treatment tank
38: cyan secondary treatment tank
440: cyanide treatment tank
40, 500: ammonia processing unit
42, 520: ammonia treatment pH adjustment tank
45, 550: nitrification tank
47, 570: denitrification tank

Claims (9)

a chromium treatment unit for reducing chromium contained in the plating wastewater;
a cyanide treatment unit for decomposing cyanide contained in the chromium-reduced plating wastewater; and
an ammonia treatment unit for nitrifying and denitrifying ammonia contained in the plating wastewater in which the cyanide has been decomposed;
including,
The decomposition treatment of the cyanide is an apparatus for purifying plating wastewater that is performed by injecting metal oxidation water into the plating wastewater.
According to claim 1,
The metal oxidation water is a purification treatment apparatus for plating wastewater that includes a compound represented by the following formula (1):
[Formula 1]
M1 _x M2 _y O ₄
(In Formula 1,
M1 and M2 are each independently H, Na, K, Fe, Zn, Sn, Cu, Pb, Sb or Al;
Wherein x and y are each independently an integer of 1 or more depending on the combination of the compound.)
According to claim 1,
The metal oxidation water is a plating wastewater purification treatment apparatus for selectively decomposing cyan compared to ammonia contained in the plating wastewater.
According to claim 1,
The amount of the metal oxidation water added is 0.1 parts by weight to 5 parts by weight based on 100 parts by weight of the plating wastewater purification treatment apparatus.
According to claim 1,
The decomposition treatment of the cyanide is a purification treatment apparatus for plating wastewater that is performed in the range of pH 4 to pH 6.
According to claim 1,
The metal oxidation number is reduced to metal hydroxide after the decomposition treatment of cyan,
The metal hydroxide is a plating wastewater purification apparatus for precipitating heavy metals contained in the plating wastewater.
According to claim 1,
The chromium treatment unit, the cyanide treatment unit and the ammonia treatment unit each include a pH adjusting tank for adjusting the pH of the plating wastewater.
According to claim 1,
The plating wastewater purification apparatus further includes a heavy metal processing unit for precipitating heavy metals contained in the chromium-reduced plating wastewater between the chromium processing unit and the cyanide processing unit.
reducing the chromium contained in the plating wastewater;
decomposing cyanide contained in the chromium-reduced plating wastewater; and
nitrifying and denitrifying ammonia contained in the plating wastewater in which the cyanide has been decomposed;
including,
The decomposition treatment of cyanide is a purification treatment method of plating wastewater that is performed by putting metal oxidation water into the plating wastewater.

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