JPH11300345A - Decomposing method of organic chlorine compound such as dioxins or the like in reclamation leachate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely and easily decompose and remove the org. chlorine compd. such as dioxins in the reclamation leachate. SOLUTION: After treating the reclamation leachate at an org. removing stage and a suspended matter removing stage, the resulting water is introduced to a reaction tank 9 provided with a UV lamp 10 and an ultrasonic oscillator 11, and the org. chlorine compd. such as dioxins incorporated in the water is decomposed by irradiating the reclamation leachate with the UV ray and the ultrasonic wave. The org. chlorine compd. is surely decomposed by a synergistic effect of the UV ray and the ultrasonic wave and also a scaling of residual calcium, etc., is prevented by the ultrasonic wave. Therefore, its handling is easy since a periodical washing of the UV lamp such as conventional ozone/UV ray reaction column and a waste ozone treatment are eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and a device for decomposing organic chlorine compounds such as dioxins in landfill leachate.

[0002]

2. Description of the Related Art Landfill leachate at a final landfill site is used, for example, in a landfill leachate treatment facility as shown in FIG.
Dust removal, sand removal and flow rate adjustment in the adjustment tank 1, heavy metals such as calcium and manganese are coagulated and settled in the calcium removal equipment 2, BOD substances and TN are decomposed and removed in the biological treatment equipment 3, and coagulation settling equipment In step 4, COD substances, suspended substances, TP and the like are coagulated and settled, and fine suspended substances are removed in a sand filtration tower 5, an ozone / ultraviolet reaction tower 6, an activated carbon adsorption tower 7
After removing COD substances such as dioxins, chromaticity components, etc. remaining in the above, the water is discharged.

[0003]

However, when ozone and ultraviolet light are used in combination for the decomposition of dioxins and the like as described above, not only the treatment of exhausted ozone is required, but also the scale of remaining calcium and suspended substances is reduced. Since it adheres to the surface of the ultraviolet lamp, periodic cleaning is required, and management becomes complicated.

An object of the present invention is to solve the above-mentioned problem, and an object of the present invention is to reliably and easily decompose and remove organic chlorine compounds such as dioxins in landfill leachate.

[0005]

In order to solve the above-mentioned problems, a method for decomposing an organic chlorine compound such as dioxins in a landfill leachate according to the present invention comprises the steps of: And irradiating the landfill leachate with ultraviolet light and ultrasonic waves to decompose organic chlorine compounds such as dioxins contained therein.

[0006] Further, a decomposer for performing the above-mentioned method for decomposing organic chlorine compounds such as dioxins in landfill leachate includes a reaction tank into which landfill leachate is introduced, and an ultraviolet ray for irradiating the landfill leachate with ultraviolet light in the tank. This is a configuration having an irradiation unit and an ultrasonic irradiation unit for irradiating an ultrasonic wave.

According to the method and apparatus described above, cavitation bubbles are generated, diffused, expanded, and collapsed in landfill leachate by ultrasonic waves, and a reaction field of thousands of degrees and hundreds of atmospheres is formed at that time. . Further, hydrogen radicals, oxygen radicals, hydroxy radicals, nitrogen radicals, etc. are generated from water around the cavity, dissolved oxygen, nitrogen, etc., and hydrogen peroxide,
Oxidizing compounds such as nitrous acid and nitric acid are generated, and organic chlorine compounds such as dioxins are decomposed by cavitation and reaction with radicals and oxidizing compounds.
In addition, ultraviolet rays mainly promote dechlorination of the organic chlorine compound. By these synergistic effects, the organic chlorine compound and the remaining COD are efficiently decomposed.

[0008] At this time, since the ultrasonic wave prevents adhesion of dirt to the ultraviolet irradiation means such as scaling of remaining calcium, the treatment can be performed without lowering the ultraviolet irradiation efficiency.

Although it depends on the conditions such as the type and concentration of the organochlorine compound, it is effective to irradiate ultrasonic waves of about 20 to 100 kHz and to use ultraviolet rays in both the wavelength ranges of 180 ± 50 nm and 250 ± 50 nm. Further, if the temperature of the landfill leachate is controlled to about 35 ° C., the cavitation intensity and the reactivity of each radical / oxidizable compound are increased.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. The landfill leachate treatment facility shown in FIG. 1 has almost the same configuration as the conventional one described with reference to FIG. 2, and a calcium removal facility 2 and a biological The processing equipment 3, the coagulation settling equipment 4, and the sand filtration tower 5 are arranged in this order. An organic chlorine decomposer 8 is provided in the subsequent stage of the sand filtration tower 5 instead of the ozone / ultraviolet reaction tower 6, and an activated carbon adsorption tower 7 is provided in the subsequent stage.

Since the devices and equipment other than the organic chlorine decomposer 8 are well known, detailed illustration and description thereof will be omitted. An ultraviolet lamp 10 is provided vertically along the axis of a cylindrical reaction vessel 9 having a bottom and a vibrator 11 a of an ultrasonic oscillator 11 is provided at the bottom of the reaction vessel 9.

In such a landfill leachate treatment facility, leachate is dust-removed, sand-removed and flow-adjusted in a regulating tank 1 and then introduced into a calcium removal facility 2 to be treated with sodium carbonate and other coagulants to remove calcium and manganese. Heavy metals are coagulated and precipitated, introduced into the biological treatment equipment 3 to decompose and remove BOD substances and TN by microorganisms, introduced into the coagulation sedimentation treatment equipment 4 and subjected to COD substances, suspended substances and TP with a coagulant. And the like are coagulated and precipitated, and introduced into the sand filtration tower 5 to remove fine suspended substances.

Then, the landfill leachate flowing out of the sand filtration tower 5 flows into the reaction tank 9 of the organic chlorine decomposing device 8 and is circulated as an upward flow toward the outflow portion. Water is irradiated with ultraviolet rays by the ultraviolet lamp 10 and ultrasonic waves by the vibrator 11a.

[0014] Thus, in a state where the adhesion of dirt to the surface of the ultraviolet lamp, such as scaling of the remaining calcium, is prevented by the ultrasonic waves, and the ultraviolet irradiation efficiency is prevented from lowering, the synergistic effect of the ultraviolet rays and the ultrasonic waves. Therefore, organic chlorine compounds in leachate, that is, dioxins (PCDD)
s + PCDFs) and, in some cases, organochlorine compounds known as persistent organic pollutants, such as aldrin, dieldrin, endrin, and other residual CO
D can be decomposed.

The ultrasonic ultraviolet treated water flowing out from the outlet of the reaction tank 9 is introduced into the activated carbon adsorption tower 7 and discharged after removing decomposition products and chromatic components contained therein.
It should be noted that the organic chlorine decomposer 8 is only a main part, and can be configured without being limited thereto. In order to increase the irradiation time of ultrasonic waves or ultraviolet rays, the organic chlorine decomposer 8 is required. Are provided in a plurality of stages in series, or a circulation pipe is provided from the outflow portion to the inflow portion of the organic chlorine decomposition device 8 to circulate the leachate.

[0016]

As described above, according to the method and apparatus of the present invention, by introducing landfill leachate into a reaction tank provided with ultraviolet irradiation means and ultrasonic irradiation means, the ultraviolet irradiation means can be ultrasonically irradiated. In a state where the UV irradiation efficiency is maintained at a high level, the organic chlorine compounds such as dioxins in the leachate and other remaining COD can be efficiently decomposed by the synergistic effect of the ultraviolet light and the ultrasonic wave in a state where the contamination of the water is prevented. it can.

Therefore, unlike the conventional ozone / ultraviolet reaction tower, it is not necessary to periodically clean the ultraviolet lamp,
Since there is no need to install an ozone injection facility or treat waste ozone, management is easy and costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic overall configuration diagram of a landfill leachate treatment facility provided with an apparatus for decomposing organic chlorine compounds such as dioxins in one embodiment of the present invention.

FIG. 2 is a flowchart illustrating a conventional landfill leachate treatment.

[Explanation of symbols]

 8 Organochlorine decomposer 9 Reaction tank 10 Ultraviolet lamp 11 Ultrasonic oscillator 11a Transducer

Claims (2)

[Claims] 1. A landfill leachate is treated in an organic matter removing step and a suspended matter removing step, and the landfill leachate is irradiated with ultraviolet rays and ultrasonic waves to contain organic chlorine compounds such as dioxins contained therein. A method for decomposing organic chlorine compounds such as dioxins in landfill leachate, comprising decomposing water. 2. A decomposition apparatus for performing a method for decomposing an organochlorine compound such as dioxins in a landfill leachate according to claim 1, wherein the reactor has a landfill leachate introduced therein and a landfill leachate in the tank. An apparatus for decomposing organic chlorine compounds such as dioxins in landfill leachate, comprising: an ultraviolet irradiation means for irradiating ultraviolet light and an ultrasonic irradiation means for irradiating ultrasonic waves.