JP2001029969A - Treatment of organochlorine compound in wastewater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment method of organochlorine compound that can treat an organochlorine compd. such as dioxins or the like in wastewater by using a small-sized apparatus not requiring a plurality of tanks to efficiently remove the same in a short time. SOLUTION: The water to be treated introduced into a reaction tank 1 is irradiated with ultraviolet rays from an ultraviolet lamp 2 while the pH thereof is adjusted to 6-10 by a pH controller 4 and, at the same time, ozone is continuously supplied to the water to be treated to remove an organochlorine compd. It is pref. that ozone is continuously introduced into the reaction tank 1 in an amt. of 300 mg or more per liter of the water to be treated in the reaction tank by using a vortex pump 3 while mixed with water to be treated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a treatment method for removing organic chlorine compounds, particularly dioxins, contained in industrial wastewater and the like.

[0002]

2. Description of the Related Art Conventionally, treatment operations for industrial wastewater and the like include coagulation sedimentation treatment and filtration treatment for removing suspended substances, biodegradation treatment for removing organic substances and nitrogen components, and adsorption treatment with activated carbon. It is done in combination. However, it has been extremely difficult with such conventional methods to effectively remove organic chlorine compounds such as dioxins.

[0003] Regarding the removal of dioxins contained in industrial wastewater and the like, Japanese Patent No. 2874126 proposes a method of ozone treatment under irradiation of ultraviolet rays. According to this method, dioxin is introduced by introducing water to be treated into a pH treatment tank to adjust the pH to neutral or weakly acidic, sending the treated water to a treatment tank, supplying ozone under irradiation of ultraviolet rays, and performing ozone treatment. Is to oxidize and remove the species.

[0004]

The above-mentioned Patent No. 287 described above.
According to the method described in Japanese Patent No. 4126, dioxins can be oxidized and removed by 80% or more. However, in this treatment method, it is necessary to circulate the water to be treated for several hours while circulating the water to be treated in the pH adjustment tank and the treatment tank. Therefore, the treatment efficiency is extremely low, and the equipment becomes large due to the combined use of the pH adjustment tank and the treatment tank. Had the disadvantage of doing so.

The present invention has been made in view of such a conventional situation,
An object of the present invention is to provide a method for treating an organic chlorine compound that can efficiently remove an organic chlorine compound such as dioxins in wastewater in a short time by using a small facility that does not require a plurality of tanks.

[0006]

In order to achieve the above object, the present invention provides a method for treating an organochlorine compound in wastewater, which comprises adjusting the pH of the water to be treated introduced into the reaction tank to pH 6 to 10 while adjusting the pH of the water to be treated. The method is characterized in that ozone is continuously supplied in a reaction tank under irradiation with ultraviolet rays to remove organic chlorine compounds.

In the treatment method of the present invention, it is preferable to continuously supply 300 mg or more of ozone per liter of the water to be treated in the reaction tank, and to mix ozone into the water to be treated by using a vortex pump. It is preferable to introduce into the reaction tank while the reaction is being performed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method of the present invention, water to be treated such as industrial wastewater containing an organic chlorine compound such as dioxins is introduced into a reaction tank by a pump, and the water to be treated is irradiated with ultraviolet rays in the reaction tank. While contacting with ozone. In the reaction tank, a reaction between ultraviolet rays and ozone generates hydroxyl radicals having a stronger oxidizing power than ozone, thereby oxidizing organic chlorine compounds such as dioxins and decomposing them into substances having a small molecular weight and removing them. .

At this time, dioxins are more easily decomposed in the alkaline region, and the pH of the water to be treated is lowered by carbon dioxide and the like generated by decomposition of organic compounds such as organic chlorine compounds. The pH of the water to be treated is always adjusted to the range of 6 to 10. PH of water to be treated
Is less than 6, the decomposition efficiency of dioxins decreases, and chlorine gas may be generated by the decomposition. Conversely, pH
Is more than 10, precipitates such as metal hydroxides are liable to be formed in the reaction tank, which lowers the efficiency of ultraviolet irradiation.

The pH of the water to be treated is adjusted such that the pH of the water to be treated is always in the range of 6 to 10 described above, preferably in the range of 9 to 10 while measuring the pH of the water to be treated in the reaction tank. This is performed by adding a pH adjusting solution such as an alkali such as sodium oxide or hydrochloric acid or another acid. Specifically, pH
A pH controller equipped with an electrode, a pH adjusting liquid and a supply pump for the same is installed in the reaction tank, and the pH of the water to be treated in the reaction tank is adjusted.
A method of supplying a pH adjusting liquid according to the fluctuation is preferable.

[0011] The amount of ozone supplied to the reaction tank is 300 mg or more, preferably 3 mg / liter of water to be treated in the reaction tank.
It is preferable to continuously supply 50 to 500 mg of ozone. If the ozone supply is less than 300 mg / l,
This is because the decomposition efficiency of the organic chlorine compound is reduced, so that the residence time in the reaction tank is increased, and it becomes difficult to efficiently remove dioxins and the like in a short time.

The method of supplying ozone to the water to be treated is as follows: a diffuser pipe system that discharges from a large number of holes formed in a pipe or the like; an ejector system that ejects from a nozzle; Can be used. In particular, if ozone is mixed with the water to be treated using a vortex pump by a turbo mixing method and the water to be treated mixed with the ozone is supplied to the reaction tank, dioxins can be removed more efficiently in a shorter time. Become.

It is preferable to use an ultraviolet lamp to irradiate the water to be treated with ultraviolet rays, and to irradiate ultraviolet rays of 185 nm or 254 nm. Further, it is desirable to appropriately adjust the number and intervals of the ultraviolet lamps to be installed in accordance with the size of the reaction tank so that sufficient ultraviolet irradiation is performed on the whole of the water to be treated in the reaction tank.

The above-mentioned method of the present invention is easy to carry out in a batch system, but the water to be treated is continuously supplied to the reaction tank,
It is also possible to perform a continuous process in which the reaction vessel overflows from the top. In either batch processing or continuous processing, when a certain amount of residence time is required, such as when the content of dioxins that are difficult to decompose is large, use a pump such as a vortex pump to remove the water to be treated in the reaction tank. Circulation is preferred.

[0015]

EXAMPLES Industrial wastewater was subjected to coagulation treatment and biodegradation treatment, and the resulting wastewater was used as water to be treated. This treated water has a dioxin concentration of 6000 pg / l (toxic equivalent conversion coefficient TE
Q130 pg / l), COD is 15 mg / l, p
H8.3.

As shown in FIG. 1, the water to be treated is treated with a vortex pump 3 at the lower part of a reaction tank 1 having an effective volume of 10 liters, in which three ultraviolet lamps 2 each having an ultraviolet output of about 3.5 W are arranged. While being introduced continuously, a part of the water to be treated in the reaction tank 1 was circulated by the vortex pump 3. The treated water overflowed from the upper part of the reaction tank 1.

At this time, 350 mg of ozone per liter of the water to be treated in the reaction tank 1 was continuously supplied to the vortex pump 3 and mixed with the water to be treated in the vortex pump 3. Also,
In the reaction tank 1, a pH controller 4 (N
PH-680D) is installed, the pH of the water to be treated in the reaction tank 1 is constantly measured by the pH electrode 5, and the pH adjusting liquid is supplied by the pump 6 according to the measured pH. The pH was always controlled between 6-8.

In this way, the water to be treated is treated with the residence time in the reaction tank 1 being adjusted to about 15 minutes.
The concentration of dioxin contained in the treated water overflowing from became 1100 pg / l (TEQ 28 pg / l), and about 80% of dioxin could be removed. Further, during this treatment operation, generation of a precipitate or chlorine gas was not recognized.

[0019]

According to the present invention, organic chlorine compounds such as dioxins in waste water can be efficiently removed by a short-time treatment using only one reaction tank. In particular, by increasing the supply amount of ozone and mixing ozone with the water to be treated by the vortex pump, it is possible to efficiently remove organic chlorine compounds such as dioxins with a shorter residence time.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing one specific example of an apparatus for carrying out the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction tank 2 Ultraviolet lamp 3 Eddy current pump 4 pH controller 5 pH electrode 6 Pump

Continued on the front page F term (reference) 4D037 AA11 AB14 BA18 BB01 CA12 CA14 4D038 AA08 AB14 BA02 BA06 BB07 BB13 BB16 4D050 AA12 AB19 BB02 BC09 BD02 BD03 BD08 CA13

Claims (3)

[Claims] 1. A method for treating an organic chlorine compound such as dioxins contained in waste water, wherein the water to be treated introduced into the reaction tank is adjusted to pH 6 to 10 while being irradiated with ultraviolet light in the reaction tank. A method for treating organic chlorine compounds in wastewater, comprising continuously supplying ozone to remove organic chlorine compounds. 2. 3 to 1 liter of water to be treated in a reaction tank
The method for treating organic chlorine compounds in wastewater according to claim 1, wherein ozone of at least 00 mg is supplied continuously. 3. Mixing ozone into the water to be treated using a vortex pump while introducing the ozone into the reaction tank.
The method for treating an organic chlorine compound in wastewater according to claim 1 or 2.