JP2874126B2 - How to remove dioxins from sewage - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing dioxins from sewage in a leachate treatment facility for industrial waste and a wastewater treatment facility for industrial wastewater.

[0002]

2. Description of the Related Art Conventionally, in a leachate treatment facility and an industrial wastewater treatment facility at a general waste disposal site, sewage is introduced into a regulating tank and a calcium removal facility as shown in a flowchart of FIG. After that, it adjusts pH and removes calcium, and then sends it to biological treatment equipment to biologically treat organic matter and nitrogen components in sewage by contact aeration and rotating disk method. Then, the biologically treated water is introduced into a coagulation tank to coagulate by adding a coagulant, and the coagulation treatment water is sent to a coagulation sedimentation tank to settle and separate the coagulate. Released as treated water.

[0003]

However, sewage such as leachate at final disposal sites and industrial wastewater as described above may contain dioxins, which are trace harmful substances, and are effectively removed therefrom. Is desired.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a method for effectively removing dioxins in wastewater.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is a method for removing dioxins in sewage such as leachate from a general waste landfill or industrial wastewater. It is introduced into the tank and adjusted to neutral or weakly acidic, and this water to be treated is sent to the treatment tank to supply ozone under irradiation of ultraviolet rays to perform ozone treatment, and the water to be treated in the treatment tank is sent to the pH adjustment tank. It will be returned.

[0006]

According to the above construction, the water to be treated, which has been adjusted to be neutral or weakly acidic, is guided to the treatment tank and subjected to ozone treatment under irradiation of ultraviolet rays. Hydroxy radicals are generated, and dioxins are effectively oxidized and removed by the hydroxyl radicals. Since the water to be treated in the treatment tank is returned to the pH adjustment tank and sent back to the treatment tank, the water stays in the treatment tank for a certain period of time while being maintained at a suitable pH, so that the treatment is ensured. In addition, a scale which is easily generated in an alkaline region is not generated, and the action of ultraviolet rays is not hindered.

[0007]

An embodiment of the present invention will be described below with reference to FIG. In the method of the present invention, the treatment is carried out using water that has passed through the sand filtration tank and the activated carbon adsorption tank in the treatment flow described above with reference to FIG. Treated water 1
The water 5 to be treated in the tank is introduced into the H adjusting tank 2 by adding an acid or an alkali 4 while stirring with a stirrer 3.
H5.8 to 8.6, and this treated water 5
To the processing tank 7. In the treatment tank 7, the water 5 to be treated is supplied from above, and the water 8 to be treated in the tank is irradiated with a wavelength 185 from an ultraviolet lamp 9 installed in the height direction of the tank.
In the state of irradiating ultraviolet rays of 254 nm or 254 nm,
Ozone 10 having an ozone concentration of 10 g / m ³ or more is injected from the bottom of the tank. At this time, the water 8 to be treated is returned to the pH adjusting tank 2 from the bottom at the same time, and a part of the water 8 to be treated flows out of the tank 7 as ozonized water 11. Thus, the pH adjustment tank 2
The water to be treated 8 is circulated between the
Is kept in the processing tank 7 for about 5 hours.

As described above, the water to be treated is adjusted to a suitable pH around neutrality, flows into the treatment tank 7 from the top, and is mixed with ozone while flowing down into the treatment tank 7 to the bottom. 185 wavelength from the ultraviolet lamp 9 installed in the height direction
Irradiation of ultraviolet light of 254 nm or 254 nm. As a result, hydroxyl radicals having stronger oxidizing power are generated in the treated water 8 by the combined use of ozone and ultraviolet rays,
Dioxins contained therein are effectively oxidized and removed. At this time, the water to be treated is circulated between the pH adjusting tank 2 and the processing tank 7 as described above, stays in the processing tank 7 for a certain time, and is maintained at a preferable neutral pH. In addition to ensuring processing, scales that are likely to occur in the alkaline region are not generated and the action of ultraviolet light is not disturbed. As a result of treating the water to be treated using both ozone and ultraviolet light, dioxins in the water to be treated were removed by 65% or more of each homologue, and 80% or more as a whole. Therefore, this method requires 0.0-48 ng / l of dioxins which are usually contained in leachate
It can be said that it is an indispensable method for removing to 1 ng / l or less.

[0009]

As described above, according to the present invention, the water to be treated, which has been adjusted to be neutral or weakly acidic in the pH adjusting tank, is sent to the processing tank, and the oxidized water generated by the combined use of the ultraviolet rays and ozone in the processing tank. Since strong hydroxy radicals act, dioxins in the water to be treated are effectively oxidized and removed by the hydroxy radicals. At this time, since the water to be treated is circulated between the pH adjustment tank and the treatment tank, the water to be treated is to remain in the treatment tank for a certain period of time while being maintained at a suitable neutral or weakly acidic pH. Become
In addition to the reliable treatment, the formation of scale which is likely to occur in the alkaline region is prevented, and the action of ultraviolet rays is not hindered.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a processing apparatus according to an embodiment in which a method of the present invention is performed.

FIG. 2 is a flowchart illustrating a conventional wastewater treatment method.

[Explanation of symbols]

 Reference Signs List 1 treated water 2 pH adjustment tank 5 treated water 7 treatment tank 8 treated water 9 ultraviolet lamp 10 ozone

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-218676 (JP, A) JP-A-5-228480 (JP, A) JP-A-6-79266 (JP, A) JP-A-4- 256433 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C02F 1/78 C02F 1/32 C02F 1/72 C02F 1/50

Claims (1)

(57) [Claims] 1. A method for removing dioxins in sewage such as leachate or industrial wastewater from a general waste final disposal site, wherein water to be treated is introduced into a pH adjusting tank to adjust the pH to neutral or weakly acidic.
A method for removing dioxins in sewage water, comprising sending the water to be treated to a treatment tank, supplying ozone under irradiation of ultraviolet rays and performing ozone treatment, and returning the water to be treated in the treatment tank to a pH adjustment tank. .