JP3716143B2 - Hazardous substance processing method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hazardous substance treatment method and apparatus for treating harmful substances such as organic halogen compounds in landfill leachate and industrial wastewater.
[0002]
[Prior art]
An outline of the basic configuration of the conventional dioxin-containing wastewater treatment is shown in FIG.
As shown in FIG. 5, in the conventional dioxin-containing wastewater treatment system, a dedicated dioxin decomposition apparatus 02 is installed in front of the coagulation sedimentation treatment equipment 01, and wastewater containing toxic substances (hereinafter referred to as “raw water”) 03. It is processing.
[0003]
The coagulation sedimentation equipment 01 adds a coagulant 04 and an alkali 05 to a suspension of solids and colloids in the raw water 03 by adding the coagulant 04 and the alkali 05, and adds a coagulant 04 and the alkali 05 to the coagulation tank 06 provided with a rapid stirring means 06a. The flocs are formed in a floc-forming tank 07 equipped with a slow stirring means 07a that flocates the agglomerates formed in the agglomeration tank 06, and are agglomerated and settled in a coagulation-precipitation tank 08 provided downstream. It is removed as agglomerated sludge 09 and treated water 010 is obtained. The reason for adding the alkali is to adjust the pH because of the aggregation reaction. For example, sodium hydroxide (NaOH) is used.
Further, depending on the quality of treated water required, sand filtration means, activated carbon adsorption means and the like are appropriately added after the coagulation sedimentation treatment.
[0004]
Here, as the dedicated dioxin decomposing apparatus 02, ozone (O ₃ ) is introduced and ultraviolet rays from an ultraviolet lamp are irradiated to generate hydroxy radicals (.OH), and the dioxins are almost completely generated by the hydroxy radicals. A decomposition method using ozone and ultraviolet rays, which makes it harmless, is used.
[0005]
In addition, an ozone hydrogen peroxide combined decomposition method using ozone and hydrogen peroxide in combination (also by OH generation) can be applied.
[0006]
The dedicated dioxin decomposition apparatus 02 is installed on the upstream side of the coagulation sedimentation equipment 01 because dioxins have low solubility in water, and most adhere to and adsorb solid substances and colloids in the raw water 03. This is because if it is installed after the coagulation / sedimentation treatment equipment 01, most of the dioxins are transferred to the coagulation sludge side and the significance of installing a dedicated decomposition apparatus is lost.
That is, simply shifting to the flocculated sludge does not cause the decomposition and detoxification, and further requires a separate detoxification process for the discharged flocculated sludge.
[0007]
[Problems to be solved by the invention]
In the processing facility as shown in FIG. 5 described above, since the dedicated dioxin decomposition apparatus 02 is separately installed, the facility cost increases and the installation area increases, and the consumption of chemicals and electric power also increases, thereby increasing the processing cost. There is a basic problem that increases.
Therefore, how to incorporate the dioxin decomposition function into another processing apparatus, avoid the installation of a dedicated decomposition apparatus, and how to reduce the processing cost are the basic issues to be solved.
[0008]
In view of the above, an object of the present invention is to provide a harmful substance processing method and apparatus capable of performing treatment of buried dioxin-containing wastewater in a compact and low cost manner.
[0009]
[Means for Solving the Problems]
The invention of [Claim 1] of the present invention that solves the above problems introduces wastewater containing dioxins that are harmful substances , aggregates fine suspensions in the wastewater by adding a flocculant , and flocs Jo and result simultaneously, in the presence of hydroxyl radicals, while adding an alkali, characterized by decomposing the harmful substances of the exhaust water.
[0010]
[Claim 2] The invention of [Claim 2] is that, in Claim 1, the generation of hydroxy radicals is a method of generating hydroxy radicals by the combined use of hydrogen peroxide and ozone, or a method of generating ozone by irradiating ozone with ultraviolet rays, or a combination of ozone and hydrogen peroxide, and wherein the more becomes that any method for generating a method, or a peroxide hydrogen hydroxy radical is irradiated with ultraviolet light to generate hydroxyl radicals is irradiated with ultraviolet light.
[0013]
The invention of the hazardous substance processing apparatus of [Claim 3 ] includes a flocculating tank for introducing a waste water containing dioxins which are harmful substances , and aggregating a fine suspension in the waste water by adding a flocculant and an alkali. A floc provided integrally with the coagulation tank, generating hydroxy radicals by hydroxy radical generating means, decomposing the harmful substances in the waste water, and making the aggregate formed in the coagulation tank into a floc form It is comprised from a formation tank, It is characterized by the above-mentioned.
[0014]
[Claim 4 ] The invention of [Claim 4 ] is that, in claim 4 or 5, the hydroxy radical generating means generates hydroxy radicals by using hydrogen peroxide and ozone together, or ozone is irradiated with ultraviolet rays to generate hydroxy radicals. Or a means for generating hydroxyl radicals by irradiating ultraviolet rays with ozone and hydrogen peroxide, or a means for generating hydrogen radicals by irradiating hydrogen peroxide with ultraviolet rays. .
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, although embodiment of this invention is described, this invention is not limited to this.
[0016]
In the present invention, the coagulation sedimentation treatment is performed, and at the same time, hardly decomposed products such as dioxins are decomposed.
As a result, the equipment cost and the installation area were reduced, and the processing cost was reduced.
[0017]
[First Embodiment]
FIG. 1 is a schematic view of a first embodiment of the present invention.
As shown in FIG. 1, the hazardous substance processing apparatus 10 of the first embodiment introduces waste water (raw water) 11 containing a harmful substance, and a fine suspension in the raw water 11 is added to the flocculant 12 and The agglomeration tank 14 is agglomerated by the addition of alkali, and is formed integrally with the agglomeration tank 14 by introducing a hydrogen peroxide solution (H ₂ O ₂ ) and an ozone-containing gas 13. And a floc forming tank 15 provided with a slow stirring means 15a for making the agglomerates floc.
According to the above apparatus, harmful substances in the raw water 11 can be decomposed in the presence of a hydroxy radical (.OH) comprising hydrogen peroxide (H ₂ O ₂ ) and ozone (O ₃ ). In addition, the suspension in the raw water can be simultaneously removed by sedimentation.
[0018]
Here, alkali (for example, NaOH, etc.) is added together with the addition of the flocculant, because the pH is lowered by the agglomeration reaction, and this is adjusted and the self-decomposition of ozone by adjusting the pH from neutral to weakly alkaline. This is because toxic substances in the raw water 11 are oxidatively decomposed by the action of strong hydroxy radicals.
[0019]
Further, the raw water 11 in the coagulation tank 14 is stirred by the generated ozone without providing a conventional stirring means, and the stirring is appropriately adjusted by adjusting the ozone introduction flow rate. ing.
[0020]
Further, in the floc forming tank 15, in order to form and grow flocs, the agitation means 15a performs slow agitation to separate and concentrate the aggregated flocs. And the coagulation sedimentation tank 16 installed in the downstream is separated and discharged | emitted as the coagulation sludge 17, and the treated water 18 by which the purification process was carried out is obtained.
[0021]
In the present invention, hydrogen peroxide water is added to the coagulation tank 14, and ozone-containing gas is rapidly blown in place of mechanical stirring of the normally used coagulation tank, and the inside of the coagulation tank is stirred by this blowing action. Like to do.
By doing in this way, a hydroxyl radical (* OH) generate | occur | produces in a coagulation tank and a dioxin decomposition reaction advances.
[0022]
Here, the hydroxy radical generating means in the present invention is based on the combined use of hydrogen peroxide solution (H ₂ O ₂ ) and ozone. Examples of the irradiation method include (2) a method of using ozone and hydrogen peroxide in combination and irradiating ultraviolet rays with an ultraviolet lamp, and (3) a method of irradiating hydrogen peroxide with ultraviolet rays using an ultraviolet lamp.
In the method of irradiating the ozone of (1) with an ultraviolet lamp (for example, a low-pressure mercury lamp: output 10 to 200 W), ultraviolet rays having wavelengths of 185 nm and 254 nm are irradiated to ozone (ozone concentration of 10 g / m ³ or more). It generates hydroxy radicals.
In the method (2) of using ozone and hydrogen peroxide in combination, the injection amount of hydrogen peroxide is, for example, 10 to 5000 mg / liter, and the injection amount of ozone is, for example, 50 to 5000 mg / liter. Irradiates ultraviolet rays to generate hydroxy radicals.
In the method (3) of irradiating the hydrogen peroxide with an ultraviolet lamp, the amount of hydrogen peroxide injected is 10 to 5000 mg / liter, and the radical is generated by irradiating with the ultraviolet lamp. is there.
[0023]
In the present embodiment, as shown in FIG. 1, as the hydroxyl radical generating means, ozone (O ₃ ) is contained in the coagulating tank 15 from the ozone generator 19 provided outside through the air diffuser 19a. By introducing bubbles and reacting the introduced ozone (O ₃ ) with hydrogen peroxide solution, ozonolysis is promoted, and as shown in the following formulas (1) and (2), a hydroxy radical (• OH).
As a combined method of ozone and hydrogen peroxide, for example, the injection amount of hydrogen peroxide may be, for example, 10 to 5000 mg / liter, and the injection amount of ozone may be, for example, 50 to 5000 mg / liter. It is not limited to.
[0024]
H ₂ O ₂ + H ₂ O ← → HO ₂ ⁻ + H ₃ O ⁻ (1)
HO ₂ ⁻ + O ₃ → .OH + .O ₂ ⁻ + O ₂ (2)
[0025]
Here, according to the reaction between ozone (O ₃ ) and hydrogen peroxide in water, harmful substances can be decomposed by the oxidative decomposition action of the generated strong hydroxyl radical (.OH).
[0026]
The raw water contains a large amount of Fe ions, Cu ions, etc., and the action of these ions can accelerate the decomposition reaction of the hydroxy radical. That is, when the ions are supplied, as shown in the following formulas (3) and (4), “.OH” is greatly generated and the decomposition promoting effect is improved.
[0027]
O ₃ + H ₂ O + Fe ²⁺ → OH + OH ⁻ + O ₂ + Fe ³⁺ (3)
O ₃ + H ₂ O + Cu ⁺ → OH + OH ⁻ + O ₂ + Cu ²⁺ (4)
[0028]
In addition, the reaction between ozone (O ₃ ) and ultraviolet (UV) irradiation in water is expressed by the following formula (5). Strong ozone generated by promoting ozone decomposition by irradiating ozone with ultraviolet light. Radicals (.OH) are generated, and harmful substances are decomposed by the oxidative decomposition action of the generated hydroxy radicals (.OH).
[0029]
O ₃ + UV → O ₂ + O, O + H ₂ O → 2.OH (5)
[0030]
Here, as hazardous substances to be decomposed in the present invention, waste water such as hazardous chlorinated aromatic compounds represented by dioxins and PCBs, landfill leachate such as highly condensed aromatic hydrocarbons, industrial wastewater, etc. Toxic substances (or environmental hormone-like substances in raw water 11 such as landfill leachate, industrial effluents, shredder dust treated effluents and smoke washing effluents that can be decomposed by hydroxy radicals of the present invention) ) Is not limited to these.
[0031]
Here, the dioxins are a general term for polyhalogenated dibenzo-p-dioxins (PXDDs) and polyhalogenated dibenzofurans (PXDFs) (X represents halogen), and halogen compounds and certain organic compounds. It is said that a trace amount is generated during the combustion of halogen compounds. Depending on the number of halogens, there are monohalides to octahalides, and among these, tetrachlorodibenzo-p-dioxin (T ₄ CDD) is known to have the strongest toxicity. Examples of harmful halogenated aromatic compounds include dioxins as well as various organic halogen compounds (for example, aromatic compounds such as phenol and benzene, such as halogenated benzenes, halogenated phenols and halogens). Toluene, etc.), alkyl halide compounds, etc.) are contained and need to be removed. That is, dioxins represent not only chlorinated dioxins but also halogenated dioxins such as brominated dioxins.
PXBs (polyhalogenated biphenyls) are a general term for compounds in which several halogen atoms are added to biphenyl, and there are isomers depending on the number of halogen substitutions and substitution positions, but in the case of PCB (polychlorinated biphenyls) 2,6-dichlorobiphenyl, 2,2'-dichlorobiphenyl, 2,3,5-trichlorobiphenyl, etc. are representative, and are highly toxic. Dioxins may be generated when incinerated. It is known as a thing and needs to be removed.
Note that PXBs naturally include coplanar PXB, which must be removed from the raw water to be discharged as treated water, and can be decomposed according to the present invention.
[0032]
PCBs (polychlorinated biphenyls) are a general term for compounds in which several chlorine atoms are added to biphenyl, and there are isomers depending on the number and position of substitution of chlorine, but 2,6-dichlorobiphenyl, 2,2 '-Dichlorobiphenyl, 2,3,5-trichlorobiphenyl, etc. are typical ones. They are highly toxic and are known to cause dioxins when incinerated. In this case, it must be removed from the raw water and can be decomposed by the present invention.
[0033]
A harmful substance treatment method using such a harmful substance treatment apparatus will be described below with reference to FIG.
[0034]
First, the raw water 11 is introduced into the coagulation tank 14 and coagulated and precipitated in the coagulation tank 14, and hydroxyl radicals are generated to oxidatively decompose and decompose harmful substances in the raw water 11. The raw water treated with harmful substances is then floc formed in the floc forming tank 15 by slow stirring 15a, and the flocs formed are removed and separated in the coagulating sedimentation tank 16, and discharged as purified treated water 18. Is done.
[0035]
According to the present invention, there is no need to install a dedicated dioxin decomposition apparatus separately as in the prior art, which increases the equipment cost and the installation area, and reduces the consumption of chemicals such as alkali and power consumption. Processing costs can be significantly reduced.
As a result, it is possible to construct a system that performs processing of dioxin-containing wastewater and the like in a compact and low-cost manner.
[0036]
In the present invention, the dioxin-containing wastewater can be applied to dioxin-containing wastewater in general. Examples of the dioxin-containing wastewater include wastewater generated from incineration systems such as garbage, industrial waste, and sludge, and waste landfill leachate.
[0037]
[Second Embodiment]
FIG. 2 is a schematic view of a second embodiment of the present invention.
As shown in FIG. 2, the hazardous substance treatment apparatus 20 of the second embodiment introduces waste water (raw water) 11 containing harmful substances, and fine suspension in the raw water 11 is added to the flocculant 12. The agglomeration tank 24 which is agglomerated by the addition and provided with the rapid stirring means 24a, and is provided integrally with the agglomeration tank 24. The aggregate formed in the agglomeration tank 24 is formed into a floc form and hydrogen peroxide solution (H ₂ O ₂ ) and a floc forming tank 25 into which the ozone-containing gas 13 is introduced.
According to the above apparatus, hydrogen peroxide solution (H ₂ O ₂ ) and ozone-containing gas are used when flocs are formed in the floc forming tank 25 after the suspension in the raw water 11 is aggregated in the coagulating tank 24. In the presence of hydroxy radicals by the action of 13, the harmful substances in the waste water can be decomposed, and the suspension in the raw water can be removed as a floc.
Unlike the first embodiment, ozone introduced into the floc forming tank 25 is introduced so as to give a gentle stirring action for floc formation.
[0038]
According to the system using the harmful substance treatment apparatus 20, the raw water 11 is introduced into the coagulation tank 24, coagulated and settled in the coagulation tank 24, and then guided to the flock formation tank 25. And oxidative decomposition by generating hydroxy radicals to decompose harmful substances in the raw water 11. The raw water treated with the harmful substances is then discharged in the coagulating sedimentation tank 16 as the treated water 18 after removing and separating the formed floc as coagulated sludge 17.
[0039]
[Third Embodiment]
FIG. 3 is a schematic view of a third embodiment of the present invention.
As shown in FIG. 3, the hazardous substance treatment apparatus 30 of the third embodiment introduces waste water (raw water) 11 containing harmful substances, and fine suspension in the raw water 11 is added to the flocculant 12. The agglomeration tank 24 which is agglomerated by the addition and provided with the rapid stirring means 24a, and is provided integrally with the agglomeration tank 24. The agglomerate formed in the agglomeration tank 24 is formed into a flock shape and an ultraviolet (UV) lamp 31. And a floc forming tank 35 into which the ozone-containing gas 13 is introduced.
According to the above apparatus, the ozone in the ozone-containing gas 13 and the ultraviolet rays of the ultraviolet (UV) lamp 31 are used when flocs are formed in the floc forming tank 35 after the suspension in the raw water is agglomerated in the aggregating tank 24. In the presence of hydroxy radicals due to the action of toxic substances, harmful substances in the waste water can be decomposed, and the suspension in the raw water can be removed as a floc.
[0040]
According to the system using the harmful substance treatment apparatus 30, the raw water 11 is introduced into the coagulation tank 24, aggregated in the coagulation tank 24, and then led to the flock formation tank 35. At the same time, it generates hydroxy radicals and oxidatively decomposes to decompose harmful substances in the raw water 11. The raw water treated with the harmful substances is then discharged in the coagulating sedimentation tank 16 as the treated water 18 after removing and separating the formed floc as coagulated sludge 17.
[0041]
[Fourth Embodiment]
FIG. 4 is a schematic view of a fourth embodiment of the present invention.
As shown in FIG. 4, the harmful substance treatment apparatus 40 of the fourth embodiment introduces waste water (raw water) 11 containing a harmful substance and removes fine suspension in the raw water 11 of the flocculant 12. Agglomeration tank 44 which is aggregated by addition, is provided with ultraviolet irradiation lamp 31 and introduces ozone-containing gas 13, and is provided integrally with aggregation tank 44, and the aggregate formed in aggregation tank 44 is in the form of a flock. And a floc forming tank 15 provided with a stirring means 15a.
According to the above apparatus, the suspended matter in the raw water is agglomerated and harmful substances in the waste water are present in the presence of hydroxy radicals due to the action of ozone of the ozone-containing gas 13 and ultraviolet rays of the ultraviolet (UV) lamp 31. Can be decomposed. The flocs are formed in the integrally formed floc forming tank 15.
[0042]
According to the system using the harmful substance treatment apparatus 40, the raw water 11 is introduced into the coagulation tank 44 and aggregated in the coagulation tank 44, and hydroxyl radicals are generated to perform oxidative decomposition, thereby causing harmful substances in the raw water 11. Disassemble. Thereafter, the floc is formed into a floc forming tank 15 to form a floc in the floc forming tank 15, and then the floc formed is removed and separated as agglomerated sludge 17 in a coagulating sedimentation tank 16 and discharged as purified treated water 18. Is done.
[0043]
【The invention's effect】
As described above, according to the invention [Claim 1] of the present invention as described, the same time when introducing wastewater containing toxic substances, aggregated by the addition of the aggregating agent of the exhaust water fine suspension, Since the harmful substances in the wastewater are decomposed in the presence of hydroxy radicals while adding alkali, the harmful substances in the raw water 11 can be decomposed in the presence of hydroxy radicals together with the aggregation treatment. it can. Thereby, while reducing the installation cost and installation area of a processing system, the processing cost can be reduced.
[0044]
According to the invention of [Claim 2], in Claim 1, the generation of hydroxy radicals is a method of generating hydroxy radicals by the combined use of hydrogen peroxide and ozone, or ozone is irradiated with ultraviolet rays to generate hydroxy radicals. method, or a combination of ozone and hydrogen peroxide, a method for generating hydroxyl radicals by irradiation of ultraviolet rays, or because the more one method of generating peroxide hydrogen hydroxy radical is irradiated with ultraviolet rays, a hydroxyl Radicals can be generated reliably and harmful substances can be decomposed.
[0045]
According to the invention of [Claim 3], at least one selected from environmental hormone-like substances such as dioxins, polychlorinated biphenyls, chlorobenzenes, chlorophenol, chlorotoluene and bisphenol A, which are harmful substances in the water to be treated. It is possible to reliably decompose the suspension and to coagulate and precipitate the suspension.
[0046]
According to the invention of harmful material treatment system of [Claim 4], the same time when introducing wastewater containing toxic substances, aggregated by the addition of flocculants and alkali of the exhaust water fine suspension, hydroxyl radicals An aggregating tank that generates hydroxy radicals by the generating means and decomposes the harmful substances in the waste water, and a slow speed that is provided integrally with the aggregating tank and the aggregate formed in the aggregating tank is flocked Since it is composed of a floc-forming tank equipped with a stirring means, the suspension in the raw water, which is the water to be treated, is aggregated and the harmful substances in the waste water are decomposed in the presence of hydroxy radicals. In addition, the aggregate from which harmful substances have been removed can be removed by aggregation and precipitation.
[0047]
According to the invention of the hazardous substance processing apparatus of [Claim 5], the waste water containing the harmful substance is introduced, and the fine suspension in the waste water is agglomerated by adding a flocculant and an alkali; It provided integrally with the flocculation tank, to generate hydroxyl radicals by a hydroxy radical generating means, harmful substances of the exhaust water and decomposed, flocculation tank to flock to and aggregate formed by agglomerated tank In the presence of hydroxy radicals, the toxic substances in the waste water are decomposed and the flocculated flocs are present in the presence of hydroxy radicals. Can be removed by agglomeration and precipitation.
[0048]
[Claim 6] According to the invention of [Claim 6], in claim 4 or 5, the hydroxy radical generating means is a means for generating a hydroxy radical by using hydrogen peroxide and ozone together, or the ozone is irradiated with ultraviolet rays to generate a hydroxy radical. , Or a means for generating hydroxy radicals by irradiating ultraviolet rays by using ozone and hydrogen peroxide together, or a means for generating hydroxy radicals by irradiating hydrogen peroxide with ultraviolet rays. Deoxy radicals can be reliably generated to decompose harmful substances.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a processing system according to a first embodiment.
FIG. 2 is a schematic diagram of a processing system according to a second embodiment.
FIG. 3 is a schematic diagram of a processing system according to a third embodiment.
FIG. 4 is a schematic diagram of a processing system according to a fourth embodiment.
FIG. 5 is a schematic diagram of a processing system according to the prior art.
[Explanation of symbols]
10 Toxic Substance Treatment Equipment 11 Wastewater containing hazardous substances (raw water)
DESCRIPTION OF SYMBOLS 12 Coagulant | flocculant 13 Ozone containing gas 14 Coagulation tank 15a Slow stirring means 15 Flock formation tank 16 Coagulation sedimentation tank 17 Aggregation sludge 18 Treated water 20 Toxic substance treatment apparatus 24a Rapid stirring means 24 Coagulation tank 25 Flock formation tank 30 Toxic substance treatment apparatus 31 UV lamp 35 Flock formation tank 40 Hazardous substance treatment device 44 Coagulation tank

Claims (4)

Drainage containing dioxins, which are harmful substances , is introduced, and the fine suspension in the wastewater is agglomerated by adding a flocculant to form a floc, and at the same time in the presence of hydroxy radicals while adding alkali. A method for treating harmful substances, comprising decomposing the harmful substances in the waste water. The method according to claim 1, wherein the generation of hydroxy radicals is a method of generating hydroxy radicals by using a combination of hydrogen peroxide water and ozone, a method of generating ozone by irradiating ozone with ultraviolet light, or ozone and hydrogen peroxide. combination, hazardous substances process wherein the more becomes that any method for generating a method, or hydroxy radical peroxide containing water is irradiated with ultraviolet to generate hydroxyl radicals is irradiated with ultraviolet light. A wastewater containing dioxins, which are harmful substances , is introduced and a fine suspension in the wastewater is agglomerated by adding a flocculant and an alkali. It is composed of a flock-forming tank that generates hydroxy radicals by means, decomposes harmful substances in the waste water, and forms agglomerates formed in the agglomeration tank to form a flock. Material processing equipment. In Claim 3 , the said hydroxy radical generation | occurrence | production means produces | generates a hydroxyl radical by combined use with hydrogen peroxide water and ozone, or the means to irradiate ozone with an ultraviolet-ray, or generate | occur | produces a hydroxyl radical, or ozone and hydrogen peroxide. A hazardous substance treatment apparatus comprising either a means for generating ultraviolet radicals by irradiating ultraviolet rays together, or a means for generating hydrogen radicals by irradiating hydrogen peroxide with ultraviolet rays.

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