JPH0565237B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to trichlorethylene- and tetrachlorethylene-contaminated water, such as trichlorethylene- and tetrachlorethylene-contaminated wastewater and drinking water, which are used as cleaning agents in the cleaning industry and electronic device parts manufacturing industry. Regarding the processing method.

[Prior Art] In recent years, it has become a problem that if trichlorethylene or tetrachlorethylene is mixed with wastewater, it may enter the human body for a long period of time and harm health.

Conventionally, the following methods have been proposed as methods for removing trichlorethylene and tetrachlorethylene from the contaminated water.

A method of adsorption and removal using substances such as activated carbon and cyclodextrin.

A separation method using pressurized reverse osmosis using a cellulose acetate membrane.

A method of aerating contaminated water to expel it from the water [Problem to be solved by the invention] However, all of the above methods only physically separate trichlorethylene and tetrachlorethylene from water, and the separated trichlorethylene and tetrachlorethylene may volatilize into the atmosphere or remain as waste in the environment, potentially causing secondary pollution. The present invention has been made in consideration of the above circumstances,
The object of the present invention is to provide a method for treating water contaminated with trichlorethylene and tetrachlorethylene, which prevents trichlorethylene and tetrachlorethylene from remaining in the environment by decomposing the trichlorethylene and tetrachlorethylene into low molecules.

[Means for Solving the Problems] In order to achieve the above object, the first claim of the present invention provides that 0.01 mol to 1 mol of trichlorethylene or tetrachlorethylene contained in water.
The second claim is characterized in that 1.2 mol of ozone is delivered, and the second claim is 0.01 mol of ozone per 1 mol of trichlorethylene or tetrachlorethylene contained in water.
It is characterized by feeding between mol and 1.2 mol of ozone through a fine filter.

As the fine filter, a glass filter with a pore diameter of about 0.2 mm is suitable.

If the amount of ozone is less than 0.01 mol per mol of trichlorethylene or tetrachloroethylene, it is not practical, and if the amount exceeds 1.2 mol, the amount of decomposition will not increase.

[Operation] When ozone generated by discharge is brought into contact with contaminated water, trichlorethylene and tetrachlorethylene in the contaminated water are decomposed by direct oxidation by ozone and by radicals generated by ozone reacting with water. Furthermore, by using a fine filter, the contact area between ozone and contaminated water increases, improving decomposition efficiency.

[Example] FIG. 1 shows an example of a processing apparatus for carrying out the present invention, in which an aeration pipe 4 equipped with a fine glass filter is installed at the tip of an ozone injection pipe 1 connected to an ozone generator 3. is attached, and this aeration pipe 4 is inserted into the treated water tank 2. 5, 6, 7
8 is a trap containing hexane, and 8 is a degassing device, which is connected to an adsorption device (not shown).

By adding distilled water to cleaning factory waste liquid, approximately
A 0.1% tetrachlorethylene solution was prepared and used as a sample.

This sample solution 1 is put into the treated water tank 2, and ozone
Air containing 10, 20, and 60 ppm is supplied from diffuser pipe 4 every minute.
When the removal rate of tetrachlorethylene was investigated at room temperature (approximately 20°C) by blowing at 2.5, the results shown in Figure 2 were obtained. Note that the removed tetrachlorethylene is collected in hexane in traps 5 to 7.

In Figure 2, the amount of ozone injected is expressed as a logarithm, but it was found that, regardless of the ozone concentration, if approximately 2 μmol or more of ozone was injected, more than 80% of tetrachlorethylene was removed.

However, even with only air without ozone,
If the ozone is blown in at 2.5 for 10 minutes, it will volatilize due to the aeration effect, so to calculate the amount of ozone decomposition, it is necessary to correct the amount of volatilization due to aeration.

FIG. 3 shows the amount of tetrachlorethylene decomposed by correcting the removal rate when only air is blown from the removal rate of tetrachlorethylene using ozone and air.

Regardless of the ozone concentration, approximately
From 2 μmol to approximately 25 μmol, approximately 250 μmol of tetrachlorethylene can be decomposed and processed within 10 minutes.
When the amount of ozone is 25 μmol or more, the amount of tetrachlorethylene decomposed increases slightly. Although not shown, this slight increasing tendency continues until the amount of ozone is 1.2 times the amount of decomposed tetrachlorethylene in terms of molar ratio. Therefore, expressed in equivalent ratio, 0.01 to 1.2 moles of ozone can decompose and decompose 1 mole of tetrachlorethylene.
It can be said that processing is possible.

The fact that more than 10 times as much tetrachlorethylene as the amount of ozone disappears from the system suggests that the decomposed compounds further chemically react with tetrachlorethylene. Moreover, as the amount of injection increases, tetrachlorethylene is volatilized from the wastewater due to the aeration effect, and the amount of tetrachlorethylene in the system decreases. Therefore, the contact with ozone becomes relatively small, and it is estimated that the amount of decomposition increases slightly when the amount of ozone is in the range of 0.1 mol to 1.2 mol per 1 mol of tetrachlorethylene.

Almost the same results were obtained for trichlorethylene, and it was found that tetrachlorethylene and trichlorethylene contained in water can be decomposed and treated in a very short time through a chemical reaction with ozone.

[Effects of the Invention] As described above, according to the present invention, trichlorethylene and tetrachlorethylene can be decomposed in a very short time by the blown ozone, and it is possible to prevent them from remaining in the environment. Furthermore, if ozone is blown through a fine filter, the decomposition efficiency of trichlorethylene and tetrachlorethylene will be improved due to the synergistic effect of the ozone decomposition ability and the action of fine ozone bubbles caused by aeration.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an apparatus for implementing the present invention, FIG. 2 is a diagram showing the removal rate of tetrachlorethylene by ozone blowing, and FIG.
The figure shows the amount of tetrachlorethylene decomposed by ozone. 2...Treatment water tank, 3...Ozone generator, 4...
...Air diffuser (with fine filter).

Claims (1)

[Claims] 1 0.01 mol to 1 mol of trichlorethylene or tetrachlorethylene contained in water
A method for treating water contaminated with trichlorethylene and tetrachlorethylene, characterized by introducing 1.2 mol of ozone. 2 0.01 mol to 1 mol of trichlorethylene or tetrachlorethylene contained in water
A method for treating water contaminated with trichlorethylene and tetrachlorethylene, which comprises sending 1.2 mol of ozone through a fine filter.