JPH0989869A - Simple analyzing method for cyan in process waste water and waste water-treating method using the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and correctly measure a concentration of cyan, by collecting a sample waste water in a flask, adding zeolite, sulfuric acid, hydroxylamine hydrochloride solution, etc., to the sample waste water, heating the sample waste water and making generated vapor come in direct touch with a color-producing liquid. SOLUTION: A rubber plug with a U-tube is set to an Erlenmeyer flask (distillation vessel) of, for example, 100ml capacity, and the U-tube is inserted in a test tube (color- producing container) while one side of the U-tube is arranged as a blow tube. Approximately 50ml of a sample solution (waste water) including cyan is collected in the flask, to which sulfuric acid solution and 5% hydroxylamine hydrochloride solution, 10% EDTA solution and zeolite are added. The flask is then heated until a fraction after boiling is about 10ml. The vapor generated by the heating is sent through the blow tube into the color-producing container to which 500mg picric acid-coloring reagent and 1ml water are added, whereby the vapor is brought in touch with a color- producing liquid. The color-producing amount is compared with a color sample, so that a concentration of cyan in the sample solution is detected. In this manner, the unnecessary excessive consumption of sodium hypochlorite is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment method in which cyanide in treated wastewater is simply analyzed and the amount of hypochlorite added to process wastewater is adjusted based on the result.

[0002]

2. Description of the Related Art Cyan is often contained in the waste water of a zinc smelter or the waste water of a plating plant, and in most cases, a cyanide removing step is provided. However, in many cases, it is common to add a hypochlorite such as sodium hypochlorite to the treated wastewater in the final step to make sure that it falls below the wastewater standard.

By the way, the concentration of cyanide in the process-treated waste water before the addition of hypochlorite is usually extremely low, and even if it is high, it is around the emission standard. Nevertheless, the reason why the hypochlorite solution is added is that the trace amount of cyanide is further decomposed to reduce the concentration of cyanide in the waste water, and it is necessary to prevent pollution. In fact, both companies set control limits well below emission standards to achieve this goal.

The amount of the hypochlorite added is usually determined by obtaining the total cyanide concentration in the treated wastewater and adjusting based on this concentration, but it is usually determined by taking a considerable safety factor, and is added excessively. . This is because the analysis of all cyanides in this wastewater is laborious and cannot be measured frequently.

JIS-K, which is an official method of all-cyan analysis
In 0102, cyanide in factory wastewater was separated by distillation in a pretreatment that required several hours, and the obtained separation liquid was used for pyridine-pyrazolone absorptiometry, 4-pyridinecarboxylic acid-pyralozone absorptiometry, ion electrode method and the like. The total cyan density is measured for the following reasons.

That is, even in the treated wastewater, an excessive amount of heavy metals, for example, heavy metals such as iron and zinc, are present with respect to the extremely small amount of cyanide present therein, and as a result, a considerable part of cyanide is present. It exists as a metal cyano complex. Therefore, it is not possible to know the exact total cyan density by using the ion electrode or by directly using various colorimetric methods.

[0007]

[Problems to be Solved by the Invention]
Usually, analysis of total cyanide concentration in treated effluent requires that a large excess of hypochlorite may be added, so that 1 to 2 weeks
It was usually done with a single measurement. I mean,
This is because the increase in the measurement frequency of all cyan is necessary to secure personnel only for that, which results in increasing the manufacturing cost. However, recent demands for cost reduction are strict, and in order to meet this demand, even the addition of a large excess of hypochlorite has been regarded as a problem.

The present invention has been made to solve such a situation, and it is an object of the present invention to provide a method that enables a simple analysis of all cyanides and a wastewater treatment method using this method. Is.

[0009]

The simple analysis method of the present invention for solving the above problems uses an apparatus having a distillation flask and a coloring container as components, and collects sample waste water into the distillation flask. Then, fluorite, sulfuric acid, hydroxylamine hydrochloride solution and EDTA solution were added to the flask,
Put the picrinsan coloring solution in the coloring container, then heat the flask, directly contact the generated vapor with the coloring liquid in the coloring container, and after the distillation, make the amount of the solution in the coloring container constant, and then use the colorimetric method. The total cyan concentration in the wastewater is obtained by detecting the amount of cyanide by detecting the amount of cyanide.

The operating method of the present invention changes the amount of hypochlorite added to the process-treated wastewater according to the value of the simple analysis method.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the simplified analysis method of the present invention, the amount of drainage of a sample collected in a distillation flask is preferably such that the total amount of cyanide contained in the sample is 250 micrograms or less. This is a constraint due to the relationship such as the amount of coloring reagent and the distillation time, and removal of this impairs the convenience. In addition, the amount of drainage of the sample that is normally collected is about 50 milliliters.

Sulfuric acid, hydroxylamine hydrochloride, EDTA
In order to stably hold interfering ions such as various metal ions existing as the metal cyano complex in the solution and facilitate the distillation of cyanide, is usually added in a large excess with respect to the target cyanide amount.

The distillation of cyan may be carried out so that the fraction is about 10 ml. The total amount of cyanide in the sample drainage is 250
This is because if the amount is less than microgram, the metal cyano complex is completely decomposed and cyan is distilled during this period. Therefore, when the distillation container and the coloring container are not directly connected, the distillation may be stopped when the outflow amount reaches 10 ml.

The fraction thus distilled does not always contain only cyan, but at least metal ions forming complex ions with cyan do not exist. Therefore, if this distillate is brought into contact with the picrinsan color-developing liquid, cyan in the distillate will develop color. By comparing this amount of color development with a color sample obtained in advance, it becomes possible to obtain the cyan concentration in the sample drainage. In the method of the present invention for comparison with a color sample, the amount of liquid in the color development container is constant.

In the operating method of the present invention, the amount of hypochlorite added is adjusted so that the cyan concentration detected by the analytical method of the present invention becomes a desired value below the control limit value. The detection frequency may be appropriately determined according to the capacity of the wastewater treatment facility.

[0016]

Next, the present invention will be further described with reference to examples.

(Embodiment 1) An Erlenmeyer flask with a capacity of 100 ml was used as a distillation container, a rubber stopper with a U-shaped tube was attached to this container, and one of the U-shaped tubes was blown into a test tube as a coloring container. did.

50 ml of each sample solution having various cyan concentrations was taken into an Erlenmeyer flask, 2 ml of (1 + 10) sulfuric acid solution was added, 1 ml of 5% hydroxylamine hydrochloride solution was added, and 10% EDTA solution was added. 1 ml was added and 10 fluorspars were added. Then, 500 mg of picrinsan coloring reagent obtained by adsorbing and drying the picric acid ethanol solution on sodium carbonate and 1 ml of water were added to the coloring container so that the tip of the blowing tube was immersed in the coloring reagent in the container.

The distillation vessel was heated, and after boiling, the heating was continued until the distillate content reached about 10 ml. In this example, the purpose was reached in 15 minutes. After that, the content of the coloring container was adjusted to 20 ml and compared with a color sample to determine the cyan concentration in the sample solution. This result and the cyan concentration of the sample solution are separately specified in JIS-
Table 1 shows the relationship with the results obtained by K0102.

[0020] From Table 1, on the low concentration side, the simplified method of the present invention and JIS-K
It can be seen that no difference from the 0102 method is observed and a slight difference is observed on the high concentration side. However, it can be said that this difference has practically no problem.

(Example 2) While the cyan concentration in the treated wastewater was measured once a day by the analysis method of the present invention, the measured value was 0.
The operation was carried out for 2 months while adjusting the amount of sodium hypochlorite added so as to be 5 ppm or less. As a result, the average addition amount of sodium hypochlorite with a concentration of 12.5% was 6
It was 00 ml / min. The amount of treated wastewater is about 400.
It was 0 m ³ / day.

(Conventional example) JIS-K010 once every two weeks
The cyanide concentration in the treated effluent was measured according to 2, and the measured value was used as a guide, and the operation was performed for 2 months while adjusting the amount of sodium hypochlorite added so that the measured value was 0.1 ppm or less. . As a result, the average addition amount of sodium hypochlorite having a concentration of 12.5% was 1400 ml / min. The amount of treated wastewater was about 4000 m ³ / day.

In this case, the reason why the concentration has to be set to 0.1 ppm or less is that the fluctuation of the cyan concentration cannot be grasped, and therefore it is necessary to take safety measures in order to surely comply with the drainage standard value. .

[0024]

As described above, the simple analysis method of the present invention is extremely simple and accurate. as a result,
According to the wastewater management method using the simple analysis method of the present invention,
Unnecessary excessive consumption of sodium hypochlorite can be prevented.

Claims (2)

[Claims] 1. An apparatus comprising a distillation flask and a coloring container as components, wherein sample wastewater is collected in a distillation flask, and fluorite, sulfuric acid, hydroxylamine hydrochloride solution and EDTA solution are put in the flask. Was added, and the picrinsan color-developing solution was placed in the color-developing container, then the flask was heated, and the generated vapor was brought into direct contact with the color-developing solution in the color-developing container to keep the amount of the solution in the color-developing container constant after distillation. After that, a simple analysis method of cyanide in the process-treated wastewater is characterized in that the amount of cyanide is detected by a colorimetric method and the total cyanide concentration in the wastewater is obtained from this. 2. A wastewater treatment method, characterized in that the amount of hypochlorite added to the process-treated wastewater is adjusted according to the value of the simple analysis method according to claim 1.