JPS589717B2 - Drainage treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for simply and efficiently treating wastewater produced in the coal and gas industry.

The main effluents emitted from the process of producing coal gas and coke through coal carbonization are coal washing effluent, gas liquid, gas washing effluent, and cooling effluent, but these effluents have a high COD and contain large amounts of cyanide, cyanide, etc. Because it contains harmful substances and pollutants such as phenols and ammonia, wastewater is generally treated.

Conventionally used treatment methods include activated sludge method, oxidative decomposition method (sodium hypochlorite treatment method) and activated carbon treatment method, but in the case of sodium hypochlorite treatment alone, Since heavy metals and cyanide form a cyano complex, it is not easy to remove cyanide compounds.

Furthermore, activated carbon treatment has a certain degree of effect in removing phenols, COD, and BOD, but cannot be expected to have much effect in removing cyanide compounds, ammonia, or decolorizing.

Therefore, the inventors of the present invention investigated various oxidizing agents in order to find a method suitable for treating the above-mentioned waste liquid generated in various processes of the coal and gas industry, and as a result, they found that chlorine dioxide was suitably used for this purpose. This invention was completed by discovering the seaweed.

That is, the first invention of the present invention is a waste liquid treatment method characterized in that a waste liquid generated from a process of producing coal gas or coke by coal carbonization is treated with chlorine dioxide.

The chlorine dioxide used in this invention may be in the form of a gas or an aqueous solution, and a mixture of chlorine dioxide and chlorine can also be used.

When carrying out this invention, an extremely simple method of adding chlorine dioxide to the waste liquid to be treated and treating it for a certain period of time can be adopted, and it is easy to perform continuous treatment as well as batch treatment.

The concentration of chlorine dioxide added is effective over a fairly wide range, and is preferably 0.1 to 10 g/l.

Further, standard treatment conditions include a treatment temperature of 0 to 50°C, a treatment pH of 3 to 12, and a treatment time of 5 to 120 minutes.

When the method according to the first invention is compared with the conventional sodium hypochlorite treatment, it has the following effects.

In other words, the removal rate of COD in the wastewater is high, and since chlorine dioxide contains 2.63 times as much oxygen as chlorine, less sodium chloride is produced during treatment, and therefore the wastewater after treatment can be reused. It's convenient when you do.

Furthermore, as shown in the Examples described later, it is advantageous in practical use that the optimum pH during treatment is on both the acidic side and the alkaline side.

The present inventors have further discovered that the treatment effect can be significantly improved by combining the above-described chlorine dioxide treatment and activated carbon treatment.

That is, the second invention of the present invention is an activated carbon treatment method, which is a waste liquid treatment method characterized in that the waste liquid generated from the process of producing coal gas or coke by coal carbonization is treated with chlorine dioxide before or after the activated carbon treatment. For example, a conventional method can be adopted in which activated carbon is introduced into the waste liquid and stirred to bring the waste liquid into sufficient contact with the activated carbon, or the waste liquid is passed through an activated carbon layer.

According to the second invention, which combines chlorine dioxide treatment and activated carbon treatment, the following effects can be obtained.

In other words, the COD removal and decolorization effects are greatly improved compared to treatment with activated carbon alone, and furthermore, harmful substances such as cyan compounds can be removed.

This invention will be explained below with reference to Examples.

Example 1 Table 1 shows the results of a comparison between chlorine dioxide treatment and sodium hypochlorite treatment.

Effluent sample (A): Effluent subjected to activated sludge treatment and coagulation sedimentation treatment pH 6.9 CODMn 100 ppm CODCr 180 ppm Chlorine dioxide concentration: 3.9 g/l (available chlorine 10.3 g/l)
l) Sodium hypochlorite: Available chlorine 145g/l) Theoretical amount of chlorine dioxide based on CODMn per 100ml of raw water: Theoretical amount of sodium hypochlorite based on CODMn per 100mA of 4J3ml raw water: 0.42'''
Treatment time: 60 minutes As is clear from Table 2, the combination of activated carbon treatment and chlorine dioxide treatment was more effective than activated carbon treatment alone.
It was observed that the removal rate of COD and T-cyan was high, and the decolorization effect was also improved.

Example 3 Table 3 shows the results of investigating the ammonia removal effect by chlorine dioxide treatment.

Effluent sample: (A) and (B) Chlorine dioxide concentration: 3.4 g/lC vs. liquid 10%) Treatment time: 60 minutes

Claims (1)

[Scope of Claims] 1. A wastewater treatment method characterized by treating wastewater generated from a process of producing coal gas and coke by coal carbonization with chlorine dioxide. 2. A wastewater treatment method, characterized in that the wastewater generated from the process of producing coal gas and coke by coal carbonization is treated with chlorine dioxide before or after being treated with activated carbon.