JPS5924671B2 - Complex cyanide processing equipment - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a treatment device for complex cyanide, such as wastewater containing a complex compound of cyanide and metal ions such as nickel, copper, or iron (hereinafter referred to as complex cyanide), which uses ozone and light in combination. It is.

As is well known, plating factories and photo development facilities discharge wastewater containing highly toxic cyanide.

In addition to free cyanide ions (free cyanide), these wastewaters contain a large amount of complex cyanide, which is a complex compound with the above-mentioned metal ions.

Complex cyanide is generally more chemically stable than free cyanide, and is often difficult to oxidatively decompose with an oxidizing agent.

Among complex cyanogens, complexes with iron ions (ferricyanide ions, ferrocyanide ions) are particularly stable, and it is difficult to treat them to the emission regulation value for cyanide even using strong oxidizing agents such as ozone. .

However, when wastewater containing such stable complex cyanogens is subjected to ozone aeration treatment while being irradiated with ultraviolet rays or near-ultraviolet to visible light, the removal rate of cyanide is accelerated compared to single treatment with ozone, and the removal rate of cyanide is reduced to low concentrations. It has been shown that it is possible to process

However, if this method is used for ozone treatment while unconditionally irradiating light, the ozone utilization efficiency will decrease and the amount of ozone required for cyanide removal will become excessive. There was a practical problem due to the large capacity of the light source.

Therefore, in order to solve this problem, the present inventor further conducted research on ozone treatment of complex cyanide under light irradiation, and as a result, discovered the following fact.

That is, for potassium ferricyanide aqueous solutions of various concentrations, we compared ozone treatment under ultraviolet irradiation using a low-pressure mercury lamp and ozone treatment under irradiation with a high-pressure mercury lamp that cuts ultraviolet rays, and obtained results as shown in Table 1. Got the results.

However, the experimental conditions conducted here are as shown below.

Reactor: Internal irradiation type (diameter 10C1rL) Ozone supply rate: 1 l/rn 1 n Ozone concentration: 17 l/rn
1-O2 Ultraviolet light source; 4W low-pressure mercury lamp Near-ultraviolet to visible light source; 100W high-pressure mercury lamp (310
(cut below mμ) From this table, the following things became clear.

First, regarding the cyan removal speed: (1) The cyan removal speed per unit power consumption of the light source is 3 to 5 times faster with ultraviolet light irradiation than with near ultraviolet to visible light irradiation.

On the other hand, the amount of ozone required to remove a unit amount of cyanide, (△03
/△CN) wtl: (1) In the case of ultraviolet light irradiation, the complex cyanide concentration is high (approximately 1
Although it is a relatively small amount of about 0.0100pp, it increases significantly as the complex cyanide concentration decreases.

(2) In the case of near-ultraviolet to visible light irradiation, when the complex cyanide concentration is high (approximately 50 ppm), it is as low as 2.4, and even if the complex cyanide concentration decreases, the increase rate is less than that of ultraviolet light irradiation. Significantly less.

This invention was made based on these studies, and the reaction vessels are multi-staged, and the concentration of complex cyanide in the first stage is relatively high (usually 100 pp
[[L or more] By the way, ozone treatment is performed while irradiating ultraviolet rays, and ozone treatment is performed while irradiating near ultraviolet to visible light that does not contain ultraviolet rays in a subsequent reaction tank where the complex cyanide concentration has been reduced (100 ppm or less) This minimizes the power consumption of the light source and the amount of ozone required.

The figure is a system diagram showing a complex cyanide processing apparatus according to an embodiment of the present invention.

Water to be treated, such as wastewater containing complex cyanide, is first continuously introduced into the reaction tank 1 at the front stage from the inlet 2.

Here, photoelectrons from a lamp 3 that mainly emits ultraviolet rays, ozone supplied from an ozone-containing gas inlet 4 supplied from an ozonizer (not shown), and complex cyanide in the water to be treated react to remove a certain amount of cyanide. be done.

The treated water containing complex cyanide that was not removed in the reaction tank 1 is discharged from the outlet 5 and flows into the reaction tank 6 through the inlet 91.7.
Ozone and complex cyanide react with the photons from the lamp 8, which does not contain ultraviolet light, in the same manner as in the previous stage, and the cyanide is removed, which is then discharged from the outlet 9.

The treated water containing complex cyanide which has not been removed in the reaction tank 1 is discharged from the outlet 5 and introduced into the reaction tank 6 from the lower part, where it is mixed with photons from the lamp 8 which does not contain ultraviolet light and ozone and in the same manner as in the previous stage. The complex cyanide reacts to remove cyanide and is discharged from the outlet 9.

Unreacted ozone in reactors 1 and 6 is discharged through respective outlets 10 and 11 and released into the atmosphere through an ozonolyzer 12 according to the known prior art.

The reaction vessels 1 and 6 used here may be of a gas-liquid reaction type, such as an ordinary diffuser one-type or ejector one-type.
The light irradiation method may be either internal irradiation or external irradiation.

As the lamp 3 used, a low-pressure mercury lamp is suitable, and as the lamp 8, a high-pressure mercury lamp that cuts wavelengths of 310 mμ or less is suitable.

By configuring as described above, complex cyanide can be effectively removed, ozone utilization efficiency can be improved, and the capacity of the light source can be made smaller than that of conventional ones.

In addition, reaction vessels 1 and 6 may be combined into one or three
There is no problem in using more than one.

As explained above, this invention improves the efficiency of ozone utilization by dividing the reaction tank into at least two parts, using ultraviolet rays in the former stage and using light that does not contain ultraviolet rays in the latter stage. , has the effect of being able to remove complex cyanogens with high efficiency.

[Brief explanation of the drawing]

The figure is a system diagram showing one embodiment of the present invention. In the figure, 1 and 6 are reaction vessels, 3 and 8 are lamps, 2 is an inlet, and 9 is an outlet.

Claims (1)

[Scope of Claims] 1. In a system in which water to be treated containing complex cyanide is treated using a combination of light and ozone in a reaction tank, the reaction tank is divided into at least two parts connected in series, and one of the parts is The water to be treated is transferred from one reaction tank to the other by using a light beam mainly containing ultraviolet rays in one reaction tank and using a light beam mainly having a wavelength in the light absorption region of complex cyanide that does not contain ultraviolet rays in the other reaction tank. A processing device for complex cyanogen that is distributed to a tank. 2. The complex cyanogen treatment apparatus according to claim 1, wherein radiation light from a low-pressure mercury lamp is used as the light beam mainly consisting of ultraviolet rays. 3. Claim 1 or 2 uses synchrotron radiation from a high-pressure mercury lamp with short wavelengths of 310 mμ or less cut off as the light beam mainly having wavelengths in the light absorption region of complex cyanide that does not contain ultraviolet rays. cyanide complex processing equipment.