JP7621889B2 - Method and system for treating electroless plating wastewater - Google Patents

Description

The present invention relates to a method for treating electroless plating wastewater and a system for treating electroless plating wastewater.

Traditionally, in the electronic components field, electroless plating films have been formed on Al or Cu patterns on flexible substrates or silicon wafer substrates.

Unlike electroplating, electroless plating is a method that can form a metal film on the surface of an object to be plated by simply immersing the object in a plating solution. It can produce a film of uniform thickness regardless of the shape or type of material, making it suitable for plating parts with complex shapes or precision.

Here, electroless plating solutions are prepared by reducing metal ions (e.g. nickel ions) contained in the solution with a reducing agent such as hypophosphite, which deposits the metal on the surface of the object to be plated. As the plating process progresses, the hypophosphite is oxidized to phosphorous acid, a waste product of the reducing agent, and accumulates. This reduces the plating deposition rate and the physical properties of the electroless plating film, making the solution unusable and requiring disposal as waste liquid.

In addition to metal ions and reducing agents, electroless plating solutions also contain organic substances such as complexing agents, so when disposing of electroless plating wastewater, these must be removed or decomposed to below wastewater standards.

As a method for treating electroless plating wastewater, for example, a method has been proposed in which wastewater containing heavy metal ions such as iron, nickel, copper, zinc, and aluminum is led from a water storage tank to a pH adjustment tank, where the pH is adjusted and the heavy metal ions are separated by sedimentation through coagulation precipitation (see, for example, Patent Document 1).

In addition, a method has been proposed in which an oxidizing agent such as hydrogen peroxide or sodium hypochlorite is added to the waste liquid containing phosphorous acid after nickel has been removed, to oxidize the phosphorous acid to orthophosphoric acid, and then a calcium salt is added to this to precipitate and remove it as calcium phosphate (see, for example, Patent Document 2).

Japanese Patent Application Publication No. 11-221575 JP 2003-112190 A

However, in the coagulation and sedimentation method described in Patent Document 1, wastewater containing heavy metals such as nickel is mixed with chelate wastewater, and the heavy metals form complex compounds that remain in the coagulation treated water, so there is a problem in that the heavy metals cannot be removed to below the regulated value of the wastewater standard.

In addition, the oxidation precipitation method described in Patent Document 2 above can remove phosphorous acid, but has the problem that it is difficult to decompose or remove organic substances such as complexing agents.

In view of the above problems, the present invention aims to provide a plating wastewater treatment method and electroless plating wastewater treatment system that can remove or decompose all metal ions, ammonia, reducing agents, reducing agent waste products, and complexing agents to levels below wastewater standards without using complex equipment or special chemicals.

In order to achieve the above object, the plating waste liquid treatment method according to the present invention is a method for treating electroless plating waste liquid that contains at least metal ions, ammonia, a reducing agent, reducing agent waste, and a complexing agent, and is characterized by comprising at least an electrolytic treatment process in which the electroless plating waste liquid is electrolyzed to remove metal ions, an ammonia volatilization process in which the ammonia in the electroless plating waste liquid that has been subjected to the electrolytic treatment process is volatilized and removed, an ultraviolet light/ozone treatment process in which the electroless plating waste liquid that has been subjected to the ammonia volatilization process is oxidized to decompose the reducing agent, reducing agent waste, and complexing agent, and a phosphate removal process in which a calcium compound is added to the electroless plating waste liquid that has been subjected to the ultraviolet light/ozone treatment process to precipitate and remove phosphate.

The plating waste liquid treatment system according to the present invention is a treatment system for electroless plating waste liquid that contains at least metal ions, ammonia, a reducing agent, reducing agent waste, and a complexing agent, and is characterized by comprising at least an electrolytic treatment device that electrolyzes the electroless plating waste liquid to remove metal ions, an ammonia treatment device that volatilizes and removes ammonia in the electroless plating waste liquid that has been electrolytically treated, an ultraviolet light/ozone treatment device that oxidizes the electroless plating waste liquid that has been ammonia volatilized to decompose the reducing agent, reducing agent waste, and complexing agent, and a phosphate treatment device that adds a calcium compound to the electroless plating waste liquid that has been ultraviolet light/ozone treated to precipitate and remove phosphate.

The present invention makes it possible to remove or decompose all metal ions, ammonia, reducing agents, reducing agent waste products, and complexing agents to levels below wastewater standards without using complex equipment or special chemicals.

1 is a schematic diagram for explaining a plating waste liquid treatment system using the plating waste liquid treatment method of the present invention. FIG. 1 is a schematic diagram for explaining an electrolytic treatment device used in a plating waste liquid treatment method of the present invention. FIG. FIG. 1 is a schematic diagram for explaining an ammonia volatilization device used in the plating waste liquid treatment method of the present invention. FIG. 1 is a schematic diagram for explaining an ultraviolet ray/ozone treatment device used in the plating waste liquid treatment method of the present invention. FIG. 1 is a schematic diagram for explaining a phosphate removal device used in the plating waste liquid treatment method of the present invention.

The plating wastewater treatment method of the present invention is described below.

<Plating waste liquid to be treated>
The plating waste liquid to which the treatment method of the present invention can be applied is not particularly limited, but examples thereof include waste liquid from plating solutions that contain metal ions, a reducing agent, and a complexing agent, such as electroless nickel plating solutions and electroless copper plating solutions, and that also contain ammonia.

This electroless nickel plating waste liquid contains, as metal ions, for example, nickel ions (Ni ²⁺ ), as reducing agent components, for example, hypophosphite ions (HPO ₂ ²⁻ ), and as reducing agent waste products, for example, phosphite ions (HPO ₃ ²⁻ ).

Examples of complexing agent components include organic acids such as citric acid, malic acid, tartaric acid, malonic acid, lactic acid, succinic acid, adipic acid, and gluconic acid, amino acids such as glycine, glutamic acid, and aspartic acid, and amine compounds such as ethylenediamine and diethanolamine. Ammonia may also be included for neutralization.

The concentrations of each component in the electroless nickel plating waste liquid being treated are not particularly limited, but for example, the concentration of nickel ions, which are metal ions, is 0.5 to 15 g/L, the concentration of hypophosphite, which is a reducing agent, is 0.5 to 100 g/L, the concentration of phosphite, which is a reducing agent waste product, is 0 to 200 g/L, the concentration of the complexing agent is 10 to 150 g/L, and the concentration of ammonia is 0 to 30 g/L.

The hypophosphite used in electroless nickel plating reduces nickel ions to metal (nickel) to become phosphite. Also, since any hypophosphite or nickel that is lacking is replenished during the plating process, the phosphite produced by the reaction may eventually accumulate to 100 g/L or more. Also, although the concentration of the complexing agent may increase or decrease slightly from the initial concentration, the amount of fluctuation is smaller than that of the accumulated phosphite.

<Method of treating plating waste liquid>
As described above, as the electroless plating solution is used, organic matter, reducing agent waste products, etc. accumulate, and the electroless plating solution is a concentrated solution containing a large amount of organic matter and reducing agent waste products. The amount of waste liquid to be treated is greater than that in the case of electrolytic plating, and therefore there is a problem that treatment is difficult using the conventional coagulation sedimentation method, oxidation precipitation method, etc.

The inventors have therefore investigated the above problems and discovered a method that can remove or decompose all metal ions, ammonia, reducing agents, reducing agent waste products, and complexing agents to levels below wastewater standards without using complex equipment or special chemicals.

The plating waste liquid treatment method of the present invention will be specifically described below with reference to the drawings. Figure 1 is a schematic diagram for explaining a plating waste liquid treatment system that uses the plating waste liquid treatment method of the present invention.

As shown in FIG. 1, the plating waste liquid treatment method of the present invention includes an electrolytic treatment process in which the plating waste liquid is electrolyzed to remove metal ions by an electrolytic treatment device 2, an ammonia volatilization process in which the ammonia in the plating waste liquid is removed by an ammonia treatment device 6, an ultraviolet light/ozone treatment process in which the plating waste liquid is oxidized by an ultraviolet light/ozone treatment device 9 to decompose the reducing agent, reducing agent waste, and complexing agent, and a phosphate removal process in which the phosphate generated by the ultraviolet light/ozone treatment process is precipitated and removed by a phosphate treatment device 16.

(Electrolytic treatment process)
A plating solution (waste plating solution) 1 used in the electroless plating process is sent from the plating tank in which the plating process was carried out to an electrolytic tank 3 in the electrolytic processing device 2 by a pump (not shown).

As the electrolytic treatment device 2, a known electrolytic treatment device capable of stirring can be used. For example, as shown in FIG. 2, an electrolytic cell 3 is provided with an anode 4 made of a platinum-titanium alloy or the like, a cathode 5 made of SUS or the like, and a stirrer 20 inside the electrolytic cell 3.

Then, the plating waste liquid 1 is electrolytically treated in the electrolytic cell 3 with a predetermined electrolytic current for a predetermined time, and the metal ions are removed. More specifically, when the plating waste liquid to be treated is the above-mentioned electroless nickel plating liquid waste, this electrolytic treatment process oxidizes the hypophosphite ions, which are the reducing agent components in the plating waste liquid 1, to phosphite ions at the anode 4, and phosphite ions, which are the reducing agent waste products, to phosphate ions, and reduces the nickel ions to nickel at the cathode 5 for precipitation treatment, making it possible to reduce the concentration of nickel ions in the plating waste liquid to 2 mg/L or less, which is the effluent standard.

When the plating waste liquid being treated is electroless nickel plating liquid, impurities such as heavy metals, iron, and zinc contained in the plating waste liquid can also be removed.

The treatment temperature during electrolytic treatment is not particularly limited, and treatment at room temperature is possible, but a temperature of 40 to 60°C is preferred from the viewpoint of reducing the burden on the equipment and improving the efficiency of electrolytic deposition.

In addition, the current density during the electrolytic treatment is preferably 2 A/dm2 ^{or more} , and more preferably 5 to 15 A/ ^dm2 , from the viewpoints of suppressing costs and power consumption and improving the efficiency of electrodeposition.

The surface area of the electrode used is preferably 0.2 dm ² /L or more, and more preferably 0.5 to 1.5 dm ² /L, from the viewpoints of suppressing costs and improving the efficiency of electrodeposition.

In addition, the pH of the plating waste liquid 1 to be electrolytically treated is not particularly limited, but when it contains ammonia (NH ₃ ), it is preferably 7 or more, more preferably 8 to 10. By carrying out the electrolytic treatment within this pH range, the ammonia is simultaneously volatilized, making it possible to shorten the treatment time in the next step (ammonia volatilization treatment step).

By carrying out this process, the substances remaining in the plating waste liquid that need to be treated are the reducing agent (which was not completely removed in this process), reducing agent waste products (which was not completely removed in this process), complexing agent, and ammonia.

(Ammonia volatilization process)
Next, the plating waste liquid 1 electrolytically treated in the electrolytic treatment device 2 is sent from the electrolytic treatment device 2 where the electrolytic treatment has been performed to a heating treatment tank 7 in the ammonia treatment device 6 by a pump (not shown).

As the ammonia treatment device 6, a heat treatment device having a known heat source can be used. For example, as shown in FIG. 3, a device having a heater 8 as a heat source and an agitator 21 installed inside a heat treatment tank 7 can be used.

When volatilizing ammonia, it is preferable to thoroughly stir the plating waste liquid 1 using the stirrer 21 so that the ammonia in the plating waste liquid 1 is thoroughly volatilized.

If ammonia remains in the plating waste liquid 1, it will turn into nitric acid in the next ultraviolet light and ozone treatment process, making it difficult to remove. However, in the present invention, the plating waste liquid 1 is heated in the heating treatment tank 7 at a predetermined temperature for a predetermined time, making it possible to volatilize and remove the ammonia in the plating waste liquid 1 (reducing the ammonia concentration in the plating waste liquid to 100 mg/L or less, which is the effluent standard).

The processing temperature during the heat treatment is not particularly limited, but from the viewpoint of reducing the burden on the equipment and improving the efficiency of volatilization of ammonia, a temperature of 40 to 60°C is preferable.

The pH of the plating waste liquid 1 is not particularly limited, but is preferably 7 or higher from the viewpoint of promoting the volatilization of ammonia, and more preferably 9 to 10 from the viewpoint of suppressing the occurrence of turbidity in the plating waste liquid 1 due to the conversion of some remaining nickel ions to nickel hydroxide.

In addition, the evaporated ammonia can be rendered harmless by nitrogenizing it using, for example, a catalytic deodorizer (not shown).

By carrying out this process, the reducing agent, reducing agent waste products, and complexing agent remain in the plating waste liquid and need to be treated.

(UV/ozone treatment process)
Next, the plating waste liquid 1 that has been heat-treated in the ammonia treatment device 6 is sent from the ammonia treatment device 6 where the heat treatment has been performed to a treatment tank 10 in the ultraviolet ray/ozone treatment device 9 by a pump (not shown).

As shown in FIG. 4, for example, the ultraviolet ray/ozone treatment device 9 may be provided with a treatment tank 10 that contains plating waste liquid 1, a pump 11 for circulating the plating waste liquid 1 contained in the treatment tank 10, an oxygen cylinder 12 that contains oxygen to be converted to ozone, an ozone generator 13 that is connected to the oxygen cylinder 12 and converts the oxygen supplied from the oxygen cylinder 12 into ozone, an ejector 14 that is connected to the ozone generator 13 and disperses the ozone generated by the ozone generator 13 into the circulating plating waste liquid 1, and an ultraviolet ray irradiation device 15 that is connected to the ejector 14 and the treatment tank 10 and irradiates the circulating plating waste liquid 1 with ultraviolet rays.

In the ultraviolet/ozone treatment device 9, oxygen supplied from the oxygen cylinder 12 is converted to ozone in the ozone generator 13, and then the ozone generated in the ozone generator 13 is dispersed into the circulating plating waste liquid 1 by the ejector 14, so that hypophosphorous acid, which is a reducing agent component in the plating waste liquid 1, is oxidized to phosphorous acid, and phosphorous acid, which is a reducing agent waste product, is oxidized to phosphoric acid, and further the complexing agent component is decomposed into carbon dioxide and water.

In addition, the ultraviolet irradiation device 15 irradiates the circulating plating waste liquid 1 with ultraviolet light, thereby increasing the efficiency of the oxidation reaction caused by the above-mentioned ozone treatment.

The treatment temperature during ultraviolet and ozone treatment is not particularly limited, but is preferably between room temperature and 50°C. This is because if the treatment temperature is below room temperature, the reaction rate may decrease and the oxidation efficiency may decrease, and if the treatment temperature is higher than 50°C, the amount of ozone dissolved in the plating waste liquid 1 may decrease and the oxidation efficiency may decrease.

The pH of the plating waste liquid 1 is not particularly limited, but is preferably 7 or less from the viewpoint of suppressing crystallization (precipitation) of the phosphate generated in the ultraviolet light/ozone treatment device 9.

By carrying out this process, the only thing in the plating waste liquid that needs to be treated is the phosphate ions generated in this process.

(Phosphate Removal Process)
Next, the plating waste liquid 1 oxidized in the ultraviolet/ozone treatment device 9 is sent from the ultraviolet/ozone treatment device 9 where the oxidation treatment has been performed to a precipitation tank 17 in the phosphate removal device 16 by a pump (not shown).

As shown in FIG. 5, for example, this phosphate removal device 16 can be equipped with a settling tank 17 that contains plating waste liquid and to which a calcium compound is added, an agitator 22 provided inside the settling tank 17, a pump 18 for sending the plating waste liquid 1 contained in the settling tank 17, and a dehydrator 19 connected to the settling tank 17 via the pump 18.

First, a calcium compound (e.g., calcium hydroxide, calcium chloride, calcium sulfate, etc.) is added to the plating waste liquid 1 contained in the settling tank 17, and the phosphate ions in the plating waste liquid 1 form phosphate (calcium phosphate) and precipitate. Next, the plating waste liquid 1 with the phosphate formed is sent via pump 18 to a dehydrator 19, where a dehydration process is carried out to separate the phosphate, which is a precipitate component, from the filtrate, and the phosphate is recovered. Note that since no compounds that require treatment remain in the filtrate, wastewater treatment is possible.

The dehydrator 19 may be, for example, a filter press, a screw press, a centrifugal dehydrator, or a belt press.

As explained above, in the present invention, by carrying out the above-mentioned electrolytic treatment process, ammonia volatilization process, ultraviolet light/ozone treatment process, and phosphate removal process in this order, it is possible to remove or decompose all of the metal ions, ammonia, reducing agents, reducing agent waste products, and complexing agents to levels below the wastewater standards without using complex equipment or special chemicals.

The above embodiment may be modified as follows:

In the above embodiment, the ammonia in the electroless plating waste liquid that has been subjected to the electrolytic treatment process is removed by volatilization, but when treating plating waste liquid that does not contain ammonia, the ammonia volatilization process may be omitted.

When treating electroless copper plating wastewater, it is possible to carry out only the electrolytic treatment process and ultraviolet light/ozone treatment process described above, and omit the ammonia volatilization process and phosphate removal process.

The invention of this application will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1
<Electroless plating waste liquid>
As electroless nickel plating waste solution, one having the following composition corresponding to six turns of use (in each turn, 30 g/L of nickel ions were replenished, and the amount of sodium hypophosphite monohydrate consumed as a reducing agent and sodium hydroxide used as a pH adjuster were added) was prepared.

Nickel sulfate (as nickel ion) 5g/L
Ammonia 6g/L
Sodium hypophosphite monohydrate 20g/L
Phosphorous acid 120g/L
Malic acid, malonic acid, lactic acid, total 50g/L

<Electrolytic treatment>
Next, the above-mentioned plating waste liquid was placed in a 10 L beaker equipped with an anode made of a platinum-titanium alloy (5 dm ² ) and a cathode made of SUS (5 dm ² ), and electrolysis was carried out for 25 hours under conditions of a current density of 10 A/dm ² , a temperature of 25° C., and a pH of 9.

Next, the concentration of each component in the plating wastewater after electrolytic treatment was measured. More specifically, the nickel ion concentration was measured using an atomic absorption spectrophotometer (manufactured by Hitachi High-Tech Science Corporation, product name: Hitachi Polarized Zeeman Atomic Absorption Spectrophotometer ZA-3300). In addition, the concentrations of ammonia, hypophosphite ions, phosphite ions, and phosphate ions were measured using a capillary electrophoresis device (manufactured by Agilent Technologies, product name: Agilent 7100 CE). In addition, the nitrate ion concentration was measured using the above capillary electrophoresis device. The above results are shown in Table 1.

<Ammonia volatilization treatment>
Next, the plating waste liquid that had been subjected to the above-mentioned electrolytic treatment was placed in a 10 L beaker and left to stand for 30 hours under conditions of a temperature of 50° C. and a pH of 9 while stirring, thereby carrying out ammonia volatilization treatment.

Then, using the method described above, the concentration of each component in the plating waste liquid after ammonia volatilization was measured. The results are shown in Table 1.

<Ultraviolet rays and ozone treatment>
Next, the plating waste liquid (8 L) that had been subjected to the above-mentioned ammonia volatilization treatment was subjected to ultraviolet light and ozone treatment for 60 hours using an ultraviolet light and ozone treatment device (manufactured by Kairin Co., Ltd., product name: UV-O3-1). More specifically, while circulating the plating waste liquid (room temperature) at 20 L/min using a pump, an ozone-containing gas was blown in at a supply rate of 8.6 g/hr for 1 L/min of the plating waste liquid using an ejector, thereby performing the ozone treatment. In addition, the circulating plating waste liquid was irradiated with ultraviolet light at a wavelength of 254 nm using an ultraviolet irradiation device, thereby performing the ultraviolet treatment.

Then, using the method described above, the concentration of each component in the plating wastewater after ultraviolet and ozone treatment was measured. The results are shown in Table 1.

<Phosphate removal treatment>
Next, 300 g of calcium hydroxide was added to 1 L of the plating waste liquid (8 L) that had been subjected to the ultraviolet light and ozone treatment, so that phosphate (calcium phosphate) was formed and precipitated. The plating waste liquid in which calcium phosphate had been formed was then pumped to a dehydrator, where dehydration treatment was carried out to separate calcium phosphate, which was a precipitate component, from the filtrate.

Then, the concentration of each component in the filtrate after removing the phosphate was measured using the method described above. The results are shown in Table 1.

(Comparative Example 1)
The plating waste liquid was treated in the same manner as in Example 1, except that the ultraviolet light and ozone treatment was not carried out, and the concentration of each component was measured. The results are shown in Table 2.

(Comparative Example 2)
The plating waste liquid was treated in the same manner as in Example 1, except that the above-mentioned ammonia volatilization treatment was not carried out, and the concentration of each component was measured. The results are shown in Table 3.

(Comparative Example 3)
The plating waste liquid was treated in the same manner as in Example 1, except that the above-mentioned electrolytic treatment was followed by the above-mentioned ultraviolet light and ozone treatment, and then the above-mentioned ammonia volatilization treatment was carried out, and the concentration of each component was measured. The results are shown in Table 4.

As shown in Table 1, in Example 1, the nickel ion concentration in the plating wastewater after electrolysis is below the effluent standard of 2 mg/L (0.8 ppm). It is also found that the electrolysis oxidizes all of the reducing agent, sodium hypophosphite, to phosphorous acid, and some of the phosphorous acid is also oxidized to phosphoric acid. In addition, because the pH of the plating wastewater 1 undergoing electrolysis is 9, the ammonia concentration is reduced from 6 g/L to 2 g/L due to the volatilization of ammonia, and it is found that the processing time in the next process (ammonia volatilization process) can be shortened.

It can also be seen that the ammonia concentration in the plating wastewater after the ammonia volatilization process is below the effluent standard of 0.1 g/L.

It can also be seen that after ultraviolet light and ozone treatment, all of the phosphorous acid in the plating wastewater is oxidized to phosphoric acid, and the complexing agent components are decomposed (decomposed into carbon dioxide and water).

In addition, in the filtrate after the phosphate removal process, the phosphoric acid in the plating wastewater has been removed (i.e., removed as calcium phosphate), and when the phosphorus concentration in the filtrate was measured using an inductively coupled plasma optical emission spectrometer (manufactured by Horiba, Ltd., product name: Ultima Expert), the phosphorus concentration was found to be below the wastewater standard of 16 ppm (1.8 ppm), indicating that no compounds requiring treatment remain and that wastewater treatment is possible.

On the other hand, in Comparative Example 1, UV and ozone treatment was not performed, and therefore, as shown in Table 2, the decomposition process of the complexing agent component and the oxidation process of the phosphorous acid were not performed, and a large amount of phosphorous acid remained in the filtrate.

In addition, in Comparative Example 2, because ammonia volatilization treatment was not performed, as shown in Table 3, ammonia remained in the plating waste liquid, and some of it became nitric acid in the next ultraviolet light/ozone treatment process, remaining in the filtrate and making it difficult to remove.

In addition, in Comparative Example 3, ammonia volatilization treatment was not performed before ultraviolet light and ozone treatment, so some of the ammonia remaining in the plating waste liquid remained as nitric acid during the ultraviolet light and ozone treatment, and when the pH was increased (set to pH = 9) during the ammonia volatilization treatment, the solubility of disodium phosphate and trisodium phosphate decreased, causing the phosphates to crystallize and precipitate, making it difficult to transport the liquid to the next process, and making it impossible to perform the next process of phosphate removal.

The plating wastewater treatment method of the present invention is particularly suitable for use in treating electroless plating wastewater that contains metal ions, ammonia, reducing agents, reducing agent waste products, and complexing agents.

Claims (4)

A method for treating an electroless plating waste solution containing at least metal ions, ammonia, a reducing agent, reducing agent waste products, and a complexing agent, comprising the steps of:
an electrolytic treatment step of electrolyzing the electroless plating waste liquid to remove the metal ions;
an ammonia volatilization step of volatilizing and removing the ammonia in the electroless plating waste solution after the electrolytic treatment step;
an ultraviolet light/ozone treatment step of oxidizing the electroless plating waste liquid after the ammonia volatilization step to decompose the reducing agent, the reducing agent waste product, and the complexing agent;
and a phosphate removal step of adding a calcium compound to the electroless plating waste liquid that has been subjected to the ultraviolet light/ozone treatment step to precipitate and remove the phosphate ,
2. A method for treating electroless plating waste liquid, wherein the reducing agent is a hypophosphite and the reducing agent waste product is a phosphite ion . 2. The method for treating electroless plating wastewater according to claim 1, wherein the metal ions are nickel ions. The method for treating electroless plating wastewater according to claim 1 or 2, characterized in that in the ammonia volatilization process, the ammonia is volatilized while stirring the electroless plating wastewater that has been subjected to the electrolytic treatment process. A system for treating electroless plating waste liquid containing at least metal ions, ammonia, a reducing agent, reducing agent waste products, and a complexing agent, comprising:
an electrolytic treatment device for electrolyzing the electroless plating waste liquid to remove the metal ions;
an ammonia treatment device that volatilizes and removes the ammonia in the electroless plating waste liquid that has been electrolytically treated;
an ultraviolet light/ozone treatment device that oxidizes the electroless plating waste liquid that has been subjected to the ammonia volatilization treatment to decompose the reducing agent, the reducing agent waste product, and the complexing agent;
and a phosphate treatment device that adds a calcium compound to the electroless plating waste liquid that has been subjected to the ultraviolet light and ozone treatment to precipitate and remove phosphate ,
13. A system for treating electroless plating waste liquid, wherein the reducing agent is a hypophosphite and the reducing agent waste product is a phosphite ion .

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