JP2001269673A - Method for processing liquid containing dioxins - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an effective method for processing dioxins in a liquid, to provide an effective method for processing dioxins in soil, and further to provide an effective method for cleaning a device which is used for the process of dioxins in a liquid. SOLUTION: Dioxins and/or coplanar PCB in a liquid are oxidized or decomposed in the presence of a catalyst and an oxygen source at a temp. of 20 to 370 deg.C under a pressure at which the liquid maintains the liquid phase. In the method for processing soil containing dioxins, the soil or ash containing dioxins is brought into contact with a liquid for extraction to obtain a liquid and the liquid is subjected to the above method to process dioxins. In the cleaning method, an alkali detergent liquid or an acid detergent liquid is introduced into a wet oxidizing device to clean the device under the conditions of a specified temperature range of the liquid and the pressure at which the liquid keeps the liquid phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a coplanar-PC
B, a method for decomposing or oxidizing so-called dioxins such as polychlorinated dibenzo-para-dioxin, polychlorinated dibenzofuran, etc. (hereinafter sometimes abbreviated as "decomposition"), more specifically contained in liquid water Coplanar PC
The present invention relates to a method for efficiently decomposing or oxidizing B, dioxins and the like.

[0002]

2. Description of the Related Art Generally, dioxins, coplanar-PC
B (hereinafter may be abbreviated as "dioxins") is chemically stable and therefore hardly decomposed, remains in the natural world semipermanently, and accumulates in soil, rivers, lakes, etc. year by year. It is a problem. Various methods have been proposed for decomposing and removing dioxins contained in soil and gas.However, in the case of liquids containing dioxins, their content is extremely low, so that dioxins contained in the liquid can be efficiently used. It is difficult to process well by the conventional processing method.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for effectively treating dioxins contained in a liquid. Another object of the present invention is to provide a method for effectively treating dioxins contained in soil. It is a further object of the present invention to provide an effective method for cleaning an apparatus used for treating dioxins contained in a liquid.

[0004]

The method of the present invention which has solved the above-mentioned problems is a method for decomposing dioxins and / or coplanar-PCB in a liquid containing dioxins and / or coplanar-PCB. Oxidizing or decomposing dioxins and / or coplanar-PCB contained in a liquid under a pressure at which the liquid maintains a liquid phase in a range of 20 ° C to 370 ° C in the presence of a catalyst and an oxygen source. The method for treating dioxins and / or coplanar-PCB in the liquid has the gist of the above.

[0005] The above-mentioned liquid may be obtained by bringing soil or ash containing dioxins and / or coplanar PCB into contact with a liquid for extraction. In this case, the dioxins and / or coplanar PCB may be used. −
A contact method may be used in which dioxins and / or coplanar-PCB are separated from soil or ash by introducing soil or ash containing PCB into the liquid for extraction.

The catalyst is at least one selected from titanium, silicon, aluminum, zirconium, manganese, iron, cobalt, nickel, cerium, tungsten, copper, silver, gold, platinum, palladium, rhodium, ruthenium and iridium. And / or a catalyst containing activated carbon.

[0007] The present invention also relates to dioxins and / or dioxins and / or coplanar-PCB-containing liquids.
Alternatively, there is provided a method for cleaning a wet oxidation treatment apparatus used for decomposing a coplanar-PCB, comprising introducing an alkali cleaning liquid or an acid cleaning liquid into the apparatus and performing cleaning under a pressure at which the cleaning liquid retains a liquid phase. This is a method for cleaning a wet oxidation apparatus.

At this time, the wet oxidizer comprises a catalyst, an adsorbent,
It is recommended that the wet oxidation treatment device incorporate at least one of the fillers.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted various studies on a method for purifying dioxins contained in a liquid, and as a result, by treating the liquid by a wet oxidation treatment, it has become possible to obtain a highly dioxin-free liquid. It has been found that purified treated water can be obtained.

The solution to be treated by the method of the present invention is not particularly limited as long as it contains a so-called dioxin. The dioxins include not only polychlorinated dibenzoparadioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) (including bromine compounds) but also polychlorinated biphenyls (PCB) such as coplanar-PCB.

Examples of the liquid containing dioxins include wastewater from waste incinerators such as smoke-washing wastewater obtained by wet-cleaning the exhaust gas from waste incinerators, wastewater from leachate and other landfills, and metals from leachate. Examples include various industrial wastewaters such as a refining industry and a pulp and paper industry, but are not particularly limited thereto.

Furthermore, the method of the present invention is not limited to dioxin-containing liquids, but can also treat dioxins contained in soil.

[0013] Such soil is not particularly limited as long as it contains dioxins. However, soil that has been sprayed with pesticides (eg, soil at a golf course) or wet smoke circulating water from a waste incineration facility penetrates. Examples include soil that has been infiltrated, leachate that has infiltrated from a landfill, fly ash or incinerated ash discharged from a waste incinerator, or soil containing these fly ash or incinerated ash.

When decomposing dioxins contained in soil, it is recommended to first extract dioxins contained in soil.

Hereinafter, a method for extracting dioxins contained in soil will be described with reference to FIG. FIG. 1 is a schematic view showing an example of an embodiment of the present invention relating to the extraction of dioxins in soil, and the apparatus that can be used in the present invention is not limited to this.

The soil containing dioxins is supplied from the soil supply line 1 to the flotation device 2, in which dioxins in the soil are transferred into the liquid for extraction. The flotation device 2 is not particularly limited as long as it can contact the supplied soil with the extraction liquid in the device. When the soil is brought into contact with the liquid in such a device, the soil from which dioxins are extracted precipitates, and the dioxins are suspended in the liquid in the form of fine particles or fine particles. Alternatively, the state of the soil and the presence of dioxins in the apparatus may not be particularly limited. The most preferred state of the presence of dioxins is a state of being dissolved in the liquid. Since dioxins are often contained in combustion residues such as ash and fly ash, the flotation device 2 desirably extracts dioxins from such combustion residues.

It is desirable that bubbles are present in the flotation device 2. Dioxins and dioxin-adhered particulate matter floating in the extract can be caused to float on the liquid surface by the bubbles. The method for causing bubbles to exist in the device is not particularly limited, but a pressurized gas (for example, 0.1 to
0.5 MPa (Gauge)) may be added to the liquid for extraction, and the liquid may be added to the flotation device 2. Such a gas is not particularly limited, but is preferably a gas having a property of not dissolving in the extraction liquid. For example, when water is used as the extraction liquid, the gas may be an ozone-containing gas, a nitrogen-containing gas, or an oxygen-containing gas. And the like, and these gases may be pressurized by a compressor or the like. Further, hydrogen peroxide may be added to the extraction liquid. Alternatively, a method such as aeration in the flotation device 2 may be employed. As a method of generating bubbles in the flotation device 2, a method of accelerating the dissolution rate of hydrogen peroxide by aeration, a catalyst, a chemical, or the like may be used. The above-described bubble generation methods can be used alone or in combination.

The extraction liquid is not particularly limited, but water is preferably used. Since dioxins are hydrophobic, it is desirable that a solvent capable of promoting the solubility of dioxins in water be added to the soil before coming into contact with the extraction liquid. The solvent having such an action is not particularly limited, and examples thereof include alcohols such as methanol.

It is desirable that the temperature of the extraction liquid in the flotation device 2 is high because the separation efficiency is high, but the temperature is not particularly limited. Desirable temperature of the extraction liquid is, for example, 5 ° C. or higher, more preferably 20 ° C. or higher, most preferably 50 ° C. or higher, and preferably 95 ° C. or lower. 95
If the temperature exceeds ℃, the liquid may be in a gas phase, and a large-sized apparatus may be required to maintain the liquid phase.

The method of adjusting the temperature of the extraction liquid is not particularly limited, but may be adjusted by using, for example, a heat exchanger (not shown) or a heater (not shown).

The method of supplying the extraction liquid is not particularly limited. However, the extraction liquid may be supplied from the extraction liquid supply line 21 to the flotation device 2. It may be supplied to the device 2.

The extraction liquid supply line 1 may be connected to the upper part of the flotation device 2 or to the lower part as shown, and the connection position is not limited.

The method of supplying the soil to the flotation device 2 may be a continuous type or a batch type. Further, it is desirable that the dioxin-containing material such as dioxins and fly ash contained in the soil be efficiently separated from the soil by contact with the extraction liquid when the soil is supplied to the flotation device 2 while stirring the soil. The stirring method at this time is not particularly limited.

According to the method of the present invention, it is desirable to first introduce the extraction liquid into the flotation device 2 and then introduce the soil into the device 2 from the viewpoint of improving the contact efficiency.

The soil from which dioxins have been removed is discharged from a soil discharge line 3. Further, the extraction solution containing dioxins is taken out from the extraction liquid discharge line 4, and the liquid may be sent to the supply tank 5 or may be sent directly to the liquid supply line 6 for wet oxidation. .

According to the method of the present invention, the dioxins and / or coplanar-PCB in the dioxins and / or coplanar-PCB-containing liquid are heated in the range of 20 ° C. to 370 ° C. in the presence of a catalyst and an oxygen source. The liquid can be oxidized or decomposed under the pressure that maintains the liquid phase.

Hereinafter, a method for oxidizing or decomposing dioxins and / or coplanar-PCB in a liquid containing dioxins and / or coplanar-PCB according to the present invention will be described with reference to FIG. It is the schematic which shows an example of an aspect, and the meaning of the wet oxidation processing apparatus which can be used by this invention is not limited to this.

The dioxin-containing liquid is supplied to the reactor 13 through the liquid supply line 6, and the pressure of the liquid is desirably increased by a pump 7 installed at an arbitrary position in the liquid supply line 6.

The space velocity (LHSV) at this time is not particularly limited.
However, the wet oxidation reactor 13 (hereinafter abbreviated as “reactor”)
I do. ) May be determined as appropriate depending on the processing capacity.
Usually, the space velocity per reactor is preferably 0.1 hr.
^-1Above, more preferably 0.5 hr^-1Above, more preferred
1 hour^-1Or more, preferably 20 hours^-1Less than,
More preferably 10 hours^-1Hereinafter, more preferably 5 hours
^-1It is recommended to adjust so that Space velocity
0.1 hr^-1If less than, treatment of dioxin-containing liquid
The amount may be reduced and excessive equipment may be required. Ma
20 hours ^-1, The pressure in the reactor 13
Dioxins may not be sufficiently decomposed.

In the present invention, it is preferable to add a cation to the dioxin-containing liquid in advance. The cation is a cation paired with a halogen ion generated by the wet oxidation treatment, and it is preferable to add such a cation to the equivalent of the halogen ion or more to form a salt. When adding cations, sodium,
It is more preferable to add an alkali metal ion such as potassium. By adding alkali metal ions to the solution, the solution can be prevented from becoming acidic during the treatment, so that, for example, not only can the durability of the material of the reactor 13 be prevented from deteriorating, but also 13, the reaction rate is also improved, and more rapid processing of dioxins becomes possible. The alkali metal ion is not particularly limited as long as it dissolves in the solution and shows basicity, and examples thereof include sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium acetate. Even if a salt containing an organic acid such as sodium acetate is added to the liquid, acetic acid is decomposed into carbon dioxide and water by wet oxidation treatment in the reactor 13.

The method for adding such a cation is not particularly limited. For example, the cation may be added to the supply tank 5.
Alternatively, an additional line (not shown) may be provided to add to the dioxin-containing liquid.

The wet oxidation treatment of the present invention can be performed in the presence of an oxygen source. In particular, when the oxygen concentration in the liquid is increased, the decomposition efficiency of dioxins in the reactor 13 can be improved, so it is desirable to supply an oxygen source to the liquid. When an oxygen source is not supplied to the liquid, dissolved oxygen in the liquid can be used as an oxygen source.

The oxygen source that can be used in the present invention is not particularly limited, and a gas containing oxygen molecules such as pure oxygen, an oxygen-enriched gas, air, ozone and / or ozone (hereinafter referred to as “oxygen-containing gas”) ) May be used, but hydrogen peroxide or an oxygen-containing gas generated in another plant may be used. Among them, the use of air is recommended from an economic viewpoint. Pure oxygen or ozone may be diluted with an inert gas before use.

The supply amount when supplying the oxygen source is not particularly limited, and it is sufficient to supply an amount effective to enhance the ability to decompose dioxins in the liquid. For example, the supply amount of the oxygen-containing gas may be determined by detecting the amount of oxygen contained in the oxygen-containing gas and appropriately adjusting the supply amount by an oxygen-containing gas flow control valve (not shown). The supply amount of the oxygen-containing gas is preferably 0.5 times or more, more preferably 1 time or more, preferably 100 times or less, more preferably 50 times or less of the theoretical oxygen demand of dioxins in the liquid. It is recommended that this be an amount. When the supply amount of the oxygen-containing gas is 0.
If the ratio is less than 5 times, dioxins may not be sufficiently decomposed and may remain in the treatment liquid obtained through the wet oxidation treatment (the liquid obtained from the liquid discharge line 7) in a relatively large amount. Further, even if the supply exceeds 100 times, the decomposition treatment capacity may be saturated, and a larger apparatus may be required.

When dioxins are treated in the presence of an oxygen-containing gas, the oxygen-containing gas is introduced from an oxygen-containing gas supply line 8 and pressurized by a compressor 9.
It is desirable that the dioxin-containing liquid is mixed with the liquid before being supplied to the heat exchanger 11.

The liquid is then sent to a heat exchanger 11 where it is preheated and then further heated by a heater 12 and supplied to a reactor 13, but the method of heating a dioxin-containing liquid is not particularly limited. Instead, the liquid may be heated by the heat exchanger 11 and / or the heater 12, and the liquid may be heated by further providing a heating means such as a heater (not shown) in the reactor 13. These heating means may be used alone or in any combination.

The dioxin-containing liquid supplied to the heat exchanger 11 may be heat-exchanged by a high-temperature processing liquid discharged and processed in the reactor 13 or a high-temperature liquid discharged from another factory. May be used for heat exchange, and the heat medium for heating the liquid is not particularly limited.

It is desirable that the dioxin-containing liquid is preheated by the heat exchanger 11 and / or the heater 12 before being supplied to the reactor 13, because the processing in the reactor 13 proceeds efficiently.

The method for supplying the dioxin-containing liquid to the reactor 13 may be any of various forms such as gas-liquid upward cocurrent, gas-liquid downward cocurrent, and gas-liquid countercurrent, and is not particularly limited.

Although the temperature of the dioxin-containing liquid in the reactor 13 is affected by other conditions, if the temperature is higher than 370 ° C., the dioxin-containing liquid cannot be brought into a liquid phase state. In addition, the heating temperature is preferably 370 ° C., because the size of the equipment and the running cost may increase.
Or less, more preferably 300 ° C or less, and still more preferably 2 ° C or less.
It is desirable that the temperature be 50 ° C. or lower. On the other hand, if the temperature of the waste water is lower than 20 ° C., it becomes difficult to efficiently decompose dioxins in the liquid.
More preferably, the temperature is set to 50 ° C. or higher.

In the present invention, it is recommended to apply pressure in the reactor so that the liquid can maintain a liquid phase. Further, it is desirable to appropriately adjust the pressure in accordance with the processing temperature so that the liquid can maintain a liquid phase in the reactor by the pressure adjusting valve 22 on the processing liquid outlet side of the reactor 13. For example, if the processing temperature is 20
When the temperature is not lower than 100 ° C. and lower than 100 ° C., the liquid is in a liquid phase even at atmospheric pressure, and may be at atmospheric pressure from the viewpoint of economy, but it is preferable to increase the pressure in order to improve the processing efficiency. . When the processing temperature is 100 ° C. or higher, the liquid often evaporates under the atmospheric pressure. Therefore, it is desirable to apply pressure so that the liquid can maintain a liquid phase. Further, for example, when the dioxin-containing liquid is smoke-cleaning wastewater obtained by wet-cleaning the exhaust gas of a waste incinerator, the temperature of the liquid is 50 ° C.
Since the temperature is often about 90 ° C., the liquid may be treated by the method of the present invention without heating.

In the wet oxidation method used in the present invention, the number, type, shape and the like of the reactors are not particularly limited, and a single reactor or a combination of a plurality of reactors used for ordinary wet oxidation can be used. For example, a single-tube reactor or a multi-tube reactor can be used. When a plurality of reactors are installed, the reactors can be arranged arbitrarily such as in series or in parallel according to the purpose.

In the present invention, the decomposition or oxidation of dioxins is mainly carried out in the reactor 13 and in the presence of a catalyst. As the catalytic wet oxidation treatment method, there are a method using a solid catalyst and a method using a homogeneous catalyst. In the present invention, any method can be used.

Examples of the catalyst which can be used in the present invention include titanium, silicon, aluminum, zirconium, manganese, iron, cobalt, nickel, cerium, tungsten, copper, silver, gold, platinum, palladium, rhodium, ruthenium and iridium. And / or a catalyst containing at least one element selected from and / or activated carbon.

In particular, as the catalyst, it is preferable to use a solid catalyst having both activity and durability under the conditions of liquid phase oxidation. For example, titanium, silicon, aluminum, zirconium, manganese, iron, cobalt, nickel, cerium And at least one element selected from tungsten, copper, silver, gold, platinum, palladium, rhodium, ruthenium and iridium, and / or a compound containing one or more elements, and / or a catalyst containing activated carbon. be able to. The activated carbon includes activated carbon fibers and the like in addition to ordinary activated carbon.

Among the above-mentioned catalysts, a catalyst containing the following catalyst A component and catalyst B component, particularly a solid catalyst, is suitably used. Here, the catalyst A component is an oxide containing at least one or more elements selected from iron, titanium, silicon, aluminum and zirconium, or activated carbon. Specific examples of the catalyst A component include metal oxides such as titanium oxide, iron oxide and zirconium oxide, and binary or multi-component oxides such as titanium oxide-zirconium oxide and titanium oxide-iron oxide. In addition to (including the composite oxide), activated carbon or a mixture of a metal oxide and activated carbon can be mentioned, but the present invention is not limited thereto. The proportion of the catalyst A component in the solid catalyst is 30% by mass.
The above is preferable, and the content is preferably 99.95% by mass or less. From the viewpoint of improving the durability of the solid catalyst, it is preferable to use the catalyst A component at a ratio of 30% by mass or more.

As the catalyst B component, manganese, cobalt, nickel, cerium, tungsten, copper, silver, gold,
It is a compound containing at least one or more elements and / or one or more elements selected from platinum, palladium, rhodium, ruthenium and iridium.

Specific examples of the catalyst B component include metals, oxides and composite oxides of the above elements, but are not intended to be limited to these. Catalyst B in solid catalyst
The proportion of the component is preferably 0.05% by mass or more, and more preferably 70% by mass or less. From the viewpoint of sufficiently decomposing dioxins in the dioxin-containing liquid, it is desirable to use the catalyst B component at a rate of 0.05% by mass or more.

Further, among the catalyst B components, at least one selected from silver, gold, platinum, palladium, rhodium, ruthenium and iridium (hereinafter, referred to as “component B-1”).
In the case of a compound containing one or more elements and / or one or more elements, the ratio (total amount) is 10% by mass of the solid catalyst.
It is desirable to do the following. If it exceeds 10% by mass, no corresponding improvement in the processing performance is recognized, and since these are expensive raw materials, the cost of the catalyst increases, which is not desirable in terms of cost.

[0050] Among the above catalyst components, at least one selected from manganese, cobalt, nickel, cerium, tungsten and copper (hereinafter referred to as "B-2 component").
In the case of a compound containing one or more elements and / or one or more elements, the ratio (total amount) is 70% by mass of the solid catalyst.
It is desirable to do the following.

The total amount of the solid catalyst is 0.05 or more, 7
If the content is within the range of 0% by mass or less, the B-1 component and the B-2 component may be combined.
Not less than 05% by mass and not more than 10% by mass,
It is recommended that the combination be 5% by mass or more and 70% by mass or less so as to be within the above range.

It is desirable that the solid catalyst contains at least one or more elements selected from the component B-1 and / or a compound containing one or more elements as the catalyst B component, since the catalytic activity is increased. Also, among the B-1 components,
It is recommended that the solid catalyst contain at least one or more elements selected from platinum, palladium, rhodium, ruthenium and iridium and / or a compound of one or more elements, because the catalytic activity is particularly high. B-2
As the component, at least one or more elements selected from manganese, cobalt, nickel and copper and / or 1
Compounds containing more than one element are preferably used.

The shape of the catalyst is not particularly limited, and may be, for example, any of a granular shape, a spherical shape, a pellet shape, and a ring shape, and may be an integrated structure such as a honeycomb shape. When processing a dioxin-containing liquid containing a suspension,
Since there is a possibility that the solid layer or the precipitate may block the catalyst layer, a honeycomb catalyst is preferably used.

In addition to these catalysts, various kinds of fillers, in-plant products, and the like may be incorporated into the reactor 13 for the purpose of agitation of gas and liquid, improvement of contact efficiency, reduction of gas and liquid drift, and the like.

The material and shape of the filling and the internal crop are not particularly limited, and those made of metal or ceramics can be used.

The dioxins are decomposed or oxidized and detoxified by the method of the present invention. In the present invention, “decomposition or oxidation of dioxins” means oxidation, decomposition, dehalogenation, etc. of dioxins. .

The dioxin-containing liquid is decomposed or oxidized in the reactor 13, and the obtained processing liquid is supplied to the processing liquid line 14.
From the heat exchanger 11 and the cooler 15 if necessary.
After being cooled appropriately, the gas and liquid are separated by the gas-liquid separator 16 into gas and liquid. At this time, the heat exchanger 11 and the cooler 15
Can be used alone or in combination. However, when they are used in combination, it is desirable to supply the processing liquid to the heat exchanger 11 and then to the cooler 15.

In the gas-liquid separator 16, the liquid level controller L
It is desirable to detect the liquid level using C and control the liquid level in the gas-liquid separator by the liquid level control valve 18 so as to be constant. Here, "constant" means that the liquid level is at a constant value or within a certain range.

The treated water is cooled without cooling or after being cooled to some extent by a cooler, discharged through a pressure regulating valve (not shown), and then separated by a gas-liquid separator 16 into gas and liquid. Is also good.

The liquid from which gas has been removed by the gas-liquid separator 16 is discharged through a liquid discharge line 17. The liquid discharged from the gas-liquid separator 16 may be sent to the liquid tank 20, or the liquid may be further processed by a known method such as biological treatment.

It is desirable that the pressure in the gas-liquid separator 16 is detected by a pressure controller PC and the pressure control valve 22 is operated to maintain the pressure at a predetermined value. The gas obtained by gas-liquid separation in the gas-liquid separator 16 may be released to the atmosphere through a gas discharge line 19, or may be further processed by a known method.

When the dioxin-containing liquid is treated by the above-described method, a highly purified treatment liquid containing almost no dioxins can be obtained.

Hereinafter, a method for cleaning a wet oxidation treatment apparatus used for decomposing or oxidizing dioxins and / or coplanar-PCB in a liquid containing dioxins and / or coplanar-PCB of the present invention will be described.

The cleaning method of the present invention comprises a heat exchanger, a heater,
Solids such as scales or sediments generated on the inner walls of equipment used for wet oxidation treatment such as reactors, or on the surface of packing materials such as adsorbents, fillers, and catalysts filled in the reactors (hereinafter referred to as “solids The cleaning method is a method that can remove the "."

In the cleaning method of the present invention, an alkali cleaning solution or an acid cleaning solution is introduced into a wet oxidation treatment apparatus used for treating dioxins as described above, and the cleaning is performed under a pressure at which the cleaning solution maintains a liquid phase. Have a gist.

By removing the solid matter, various effects such as improvement of the thermal efficiency of the apparatus, improvement of the catalyst activity, and improvement of the catalyst life can be obtained.

Further, by periodically cleaning using the cleaning method of the present invention, the above-described method for treating dioxins of the present invention can be stably performed, and high processing efficiency can be maintained.

In the present invention, the term “scale-producing substance” means a substance that causes the formation of scales or solids such as sediments inside the wet oxidation treatment apparatus.
Specifically, heavy metals, aluminum, phosphorus, silicon,
At least one element selected from the group consisting of calcium and magnesium. Here, heavy metals are at least one or more elements selected from the group consisting of iron, chromium, copper, nickel, cobalt, manganese, cadmium, zinc, tin, antimony, lead, thallium, mercury, arsenic, and bismuth. is there. The state of these scale-forming substances is not particularly limited, and examples include various forms of ions or organometallic compounds.

The “solid matter such as scale or sediment” in the present invention is a substance in which these scale-forming substances are in the form of insoluble or hardly soluble oxides or various salts.

In the present invention, the term "washing treatment" means the implementation of the washing method of the present invention to remove these products and solids, and the term "washing effect" means the effect of the washing method of the present invention. It means removal of products and solids.

The object to be cleaned by the cleaning method of the present invention may be any apparatus used for wet oxidation of dioxins as described above, such as the equipment, piping, and the like of the wet oxidation apparatus.
Further, although the structure and the packing are not particularly limited, the cleaning method of the present invention is particularly applicable to a packing such as a catalyst, an adsorbent, and a filler,
Effective for cleaning reactors, heat exchangers, heaters, and piping.

The reactor may be of a type that is used as an empty column without filling the inside, or may be of a type in which a catalyst is charged and a catalyst wet oxidation treatment is performed. The reactor may be filled with filler such as metal or ceramic to improve the contact efficiency of liquid and gas, or may be filled with adsorbent such as ceramic to generate scale. A type that adsorbs and removes a substance or the like may be used. The materials and shapes of these catalysts, fillers, and adsorbents (hereinafter sometimes abbreviated as “fillers”) are not particularly limited, and various fillers are used.

When the packing is present in the reactor, it is difficult to continue the treatment because the scale is formed on the packing surface and becomes slightly clogged, or the surface is completely clogged and a predetermined flow rate cannot be obtained. There was something. In particular, when a catalyst (solid catalyst) is filled, there is a problem that when the scale is formed on the surface of the catalyst, the catalytic activity is reduced or the life of the catalyst is shortened. Such a problem can be solved by using the cleaning method of the present invention.

The inner surface of the apparatus used for the wet oxidation treatment, that is, the material that comes into contact with the liquid to be treated (hereinafter sometimes abbreviated as “material of the apparatus”) is not particularly limited as long as it is a commonly used material. For example, titanium, titanium-palladium, zirconium, SUS, Hastelloy (registered trademark), PVC,
Polyethylene, polypropylene, Teflon (registered trademark)
Are preferred. Further, even a metal material surface coated with Teflon (registered trademark) or the like can be used. PVC, polyethylene, polypropylene, and the like need to be cleaned at a low temperature because the strength of the device material is reduced at a high temperature.

When an acid washing solution described later is used, SU
Although it has a cleaning effect on S, the corrosion resistance of SUS may be deteriorated, so lower the processing temperature, lower the acid concentration, and further increase the iron or copper concentration. It is recommended to do

As a cleaning solution that can be used in the present invention, an alkali cleaning solution or an acid cleaning solution is suitably used. The components of the alkaline cleaning solution are not particularly limited, but sodium hydroxide and / or potassium hydroxide are recommended from the viewpoint of the cleaning effect.

The alkali concentration in the alkali cleaning solution is not particularly limited, but is preferably 1 g / liter or more because a high cleaning effect can be obtained. It is recommended that the amount be 10 g / liter or more, since a higher cleaning effect can be obtained. When the concentration is less than 1 g / liter, the cleaning effect may be significantly reduced. When the amount is less than 10 g / liter, the amount of the alkaline cleaning liquid used is large, so that the treatment of the alkaline cleaning liquid after the cleaning may be complicated, and the processing temperature may be relatively low in order to complete the cleaning processing in a short time. Unless the temperature is increased, a sufficient cleaning effect may not be obtained.

The alkali concentration is preferably 40 in total.
0 g / liter, more preferably 300 g / liter.
Less than a liter. When it is 400 g / liter or more, the viscosity of the alkaline cleaning liquid may increase, and supply of the alkaline cleaning liquid may be difficult. When the concentration is 400
In the case of g / liter or more, if the temperature is increased, the corrosion resistance of the device material of the device to be cleaned may decrease, which is not desirable. The alkali concentration can be appropriately changed during the cleaning treatment as long as it is within the above range.

As the alkaline cleaning liquid of the present invention, a cleaning liquid containing sodium hydroxide and a cleaning liquid containing potassium hydroxide are used as suitable cleaning liquids. However, no significant difference is observed in the cleaning effect under the same conditions such as concentration and temperature. From the viewpoint of cost, it is recommended to use a washing solution containing sodium hydroxide. Further, a cleaning solution using sodium carbonate and / or potassium carbonate is desirable because the corrosion resistance of the material of the apparatus can be further suppressed. In addition, lithium hydroxide, cesium hydroxide, rubidium hydroxide and the like can be used in the cleaning method of the present invention, but they are not desirable because they increase the cost.

The temperature of the cleaning solution when using an alkaline cleaning solution is not particularly limited, but is preferably 50 ° C. or higher, more preferably 130 ° C. or higher, and preferably 3 ° C. or higher.
The temperature is not higher than 00 ° C, more preferably not higher than 270 ° C. If the temperature is lower than 50 ° C., a sufficient cleaning effect may not be obtained. When the temperature exceeds 300 ° C., the cleaning time can be shortened and the cleaning effect can be improved, but the pressure must be increased in order to maintain the liquid phase of the cleaning liquid, and a large size is required to maintain the liquid phase. It is not preferable because the above-mentioned facilities may be required.

When the substance to be removed by the cleaning method of the present invention is a solid substance such as a scale or a sediment mainly composed of aluminum, phosphorus, and silicon, an alkaline cleaning liquid is particularly effective, but the substance is made of iron. In the case of a solid containing as a main component, the use of an alkaline cleaning liquid stabilizes the structure of iron as diiron trioxide, which may make it difficult to wash and remove the solid. It is preferable to use an acid washing solution.

An acid cleaning liquid can be used as the cleaning liquid of the present invention instead of the alkaline cleaning liquid. The acid that can be used as the washing liquid is not particularly limited, but hydrochloric acid or sulfuric acid is recommended from the viewpoint of the washing effect.

The acid concentration in the acid cleaning solution is not particularly limited, but is preferably 3 g / liter or more because a high cleaning effect can be obtained. If it is 10 g / liter or more,
It is recommended because a higher cleaning effect can be obtained. The concentration is 3
If the amount is less than g / liter, the cleaning effect may be significantly reduced. When the amount is less than 10 g / liter, the amount of the acid washing solution used is large, so that the treatment of the acid washing solution after washing may be complicated, and the treatment temperature may be relatively low in order to complete the washing process in a short time. Unless the temperature is increased, a sufficient cleaning effect may not be obtained.

The acid concentration is preferably 700 g /
Less than 1 liter, more preferably less than 300 g / liter. When the amount is 700 g / liter or more, the viscosity of the acid cleaning liquid may increase, and supply of the acid cleaning liquid may be difficult. If the concentration is 700 g / liter or more, increasing the temperature is undesirable because the corrosion resistance of the material of the device to be cleaned may be reduced. The acid concentration can be appropriately changed during the cleaning treatment as long as the acid concentration is within the above range.

The acid cleaning solution of the present invention may contain hydrochloric acid and sulfuric acid, and the respective concentrations can be appropriately selected within the above range. As the acid cleaning solution of the present invention, it is most recommended to use hydrochloric acid capable of exhibiting a high cleaning effect irrespective of the composition of the solid.

When the substance to be removed by the cleaning method of the present invention is a solid substance such as a scale or a precipitate containing iron, aluminum, phosphorus, silicon, calcium, or magnesium as a main component, the acid cleaning liquid is particularly effective. .

The washing temperature when using an acid washing solution is not particularly limited, but is preferably 10 ° C. or higher, more preferably 50 ° C. or higher, and preferably 200 ° C. or lower.
The temperature is more preferably 100 ° C or lower. When the temperature is 100 ° C. or lower, operation at normal pressure becomes possible and operability is improved, which is preferable. If the washing temperature is 50 ° C. or higher, it is recommended that the washing time can be shortened and the washing power is improved. If the processing temperature exceeds 200 ° C. and hydrochloric acid and / or sulfuric acid is contained as an acid cleaning solution, particularly when the concentration of hydrochloric acid and / or sulfuric acid is high, the corrosion resistance of the material of the apparatus may be reduced.

Therefore, when the temperature is high and the concentration of hydrochloric acid and / or sulfuric acid contained in the pickling solution is high, it is recommended to add heavy metal ions and / or heavy metal compounds to the pickling solution. Addition of heavy metal ions and / or heavy metal compounds can reduce corrosion of device materials. In this case, it is preferable to perform the treatment at a cleaning temperature of less than 160 ° C. from the viewpoint of reducing the corrosion.

Heavy metal ions added to the acid washing solution and / or
Alternatively, examples of the heavy metal compound include compounds containing at least one or more ions and / or one or more selected from iron, copper, chromium, manganese, nickel, cobalt, cerium, and the like. Or a copper ion and / or a compound containing these. Further, heavy metal ions are preferable to heavy metal compounds, and among heavy metal ions, ions having a high oxidation number are more preferable.

The heavy metal ion and / or heavy metal compound is not particularly limited as long as it can be dissolved as an ion in an acid washing solution. In the case of an iron ion, it is preferably trivalent. 2 in case
It is preferably a valence.

The concentration of iron ions and / or copper ions is not particularly limited, but the total is preferably 50 mg /
It is desirable that it is contained in the cleaning liquid at a rate of at least 100 liters, more preferably at least 100 mg / liter, preferably at most 100 g / liter, more preferably at most 10 g / liter. When the amount is less than 50 mg / liter, a sufficient effect of preventing the acid cleaning solution from deteriorating the corrosion resistance of the device material may not be obtained. Also 100
If the content is more than g / liter, it is not preferable because solids increase in the treatment of the washing solution after washing.

The concentration of the heavy metal ions and / or heavy metal compounds can be changed as appropriate according to the processing conditions such as the processing temperature and the acid concentration in the cleaning solution. For example, when the treatment temperature is high, or when the acid concentration in the cleaning solution is high, it is desirable to increase the concentration of iron ions and / or copper ions. For example, when the processing temperature is 90 ° C. and the concentration of hydrogen chloride is 100 g / liter, the total concentration of iron ions and / or copper ions is 300 mg / liter or more.
It is effective that the amount is less than g / liter.

It is preferable to adjust the concentration by adding iron ions and / or copper ions appropriately so that the iron ions and / or copper ions present in the cleaning solution have the above-mentioned concentration.

The form of iron ions and / or copper ions to be added to the acid washing solution is not particularly limited.
In the case of iron ions, it is effective to add iron salts such as ferric chloride, ferric sulfate, ferric nitrate, and ferric acetate. In the case of copper ions, cupric chloride, Cupric sulfate,
It is effective to add copper salts such as cupric nitrate and cupric acetate. Among these, it is particularly preferable to add chlorides or sulfates.

Although iron and copper have been described above, at least one or more selected from chromium, manganese, nickel, cobalt, and cerium can also be used without departing from the spirit of the present invention.

The processing pressure at the time of cleaning according to the present invention is appropriately selected depending on the correlation with the processing temperature, and is determined under the pressure at which an alkali cleaning liquid or an acid cleaning liquid (hereinafter abbreviated as “cleaning liquid”) maintains a liquid phase. It is desirable to carry out a cleaning process.

In the cleaning treatment of the present invention, it is desirable to add and use an oxidizing agent in the cleaning liquid. The oxidizing agent is not particularly limited, and for example, an oxygen-containing gas, an ozone-containing gas, hydrogen peroxide, or the like is used. Oxygen and / or ozone can be appropriately diluted with an inert gas or the like before use.
The use of air as an oxidizing agent is recommended from an economic viewpoint, but an oxygen-containing exhaust gas generated from another plant may be used as appropriate.

The amount of the oxidizing agent used is not particularly limited, but when the material of the device is a metal, it is effective that the amount is more than a necessary amount capable of forming an oxide film of the material.
If the amount is less than the required amount for forming the oxide film of the material, a problem may occur in the corrosion resistance of the material of the device. When the oxidizing agent is a gas containing oxygen and / or ozone, the oxygen concentration in the gas (in the case of ozone or the like, the concentration in terms of oxygen) is preferably 5% or more, more preferably 10%.
Not less than 100%, preferably 3%
0% or less. The supply amount of the oxidizing agent can be appropriately adjusted and supplied by providing an oxidizing agent flow rate measuring device (not shown).

The method of supplying the oxidizing agent to the cleaning liquid is not particularly limited. For example, the oxidizing agent may be supplied from the oxygen-containing gas supply line 8 or supplied in a gas-liquid mixed state together with the cleaning liquid of the present invention. It may be supplied from the line 6.

The time required to carry out the cleaning method of the present invention is not particularly limited, and is preferably 1 hour or more, more preferably 2 hours or more, preferably 48 hours or less, more preferably 24 hours or less. It is desirable to do.
If the time is less than 1 hour, the washing may be insufficient. If the time is more than 48 hours, the time for the washing is too long and the time for the original wastewater treatment is reduced, which is not preferable.

In the cleaning process of the present invention, the cleaning liquid is always supplied.
The cleaning method may be a continuous cleaning method in which the cleaning is performed in a state where the cleaning liquid is discharged, or a batch method in which the cleaning liquid is drawn out after the cleaning is performed for a certain period of time in a processing apparatus.

The amount of the cleaning solution can be appropriately changed depending on the conditions of the cleaning, and is not particularly limited. However, it is usually preferably at least 1 times the inner volume of the processing apparatus to be cleaned, and more preferably. It is preferably at least 3 times, preferably at most 20 times, more preferably at most 15 times. In addition, the space velocity of the cleaning liquid (LHSV)
It is preferably 0.01 hr ^-1 or more, more preferably 0.1 hr ^-1 or more, preferably is preferably 100 hr ^-1 or less, more preferably 10 hr ^-1 or less. For example, in a continuous cleaning method, the space velocity of the cleaning liquid may be 1 hr ^-1 and the processing time may be about 1 to 20 hours. Further, in the case of a batch type, washing may be repeated about 1 to 20 times, and it is desirable that the washing liquid is retained in the apparatus for about 1 hour in one operation.

The direction of the flow of the cleaning liquid in the processing apparatus may be the same as that in the normal wastewater treatment operation or may be the opposite direction, but the opposite direction is more effective and desirable. . When the cleaning is performed in a batch system, the direction in which the cleaning liquid is supplied to the processing apparatus and the direction in which the cleaning liquid is withdrawn may be the same or opposite, but the same direction is more effective.

A method of extracting a cleaning liquid after cleaning (hereinafter, sometimes referred to as “cleaning waste liquid”) from the apparatus is as follows.
The liquid may be extracted from the liquid discharge line 17 or the liquid supply line 6 used during normal drainage operation, or may be extracted from another line, and is not particularly limited. In the case of the batch-type cleaning method, the line to which the cleaning liquid is supplied and the line to withdraw may be the same.

The washing waste liquid may be disposed of after adjusting the pH or performing solid-liquid separation, if necessary, or may be disposed in a known manner such as biological treatment, chemical treatment, or physical treatment. Processing can also be performed.

When the washing waste solution is an acid washing solution, it is recommended to use an alkali as a pH adjuster. The alkali is not particularly limited, and various alkalis such as sodium hydroxide and sodium carbonate can be used. When the washing waste liquid is an alkaline washing liquid, it is recommended to use an acid as a pH adjuster. The acid is not particularly limited, and various acids such as hydrochloric acid and sulfuric acid can be used.

The solid-liquid separation method in the case where the washing waste liquid is subjected to solid-liquid separation is not particularly limited, and can be appropriately performed using a known solid-liquid separation method or solid-liquid separation device. As the solid-liquid separation device, various devices such as a sedimentation treatment device, a centrifugal separation treatment device, and a filtration separation treatment device may be used. Etc. may be added. The addition of these additives improves the solid-liquid separation processing speed and separation efficiency of the washing waste liquid, and is therefore preferably added. The flocculant, flocculant, and filter aid are not particularly limited, and known ones may be used.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following Examples do not limit the present invention, and all modifications and alterations that do not depart from the spirit of the present invention will be described. Included in the scope.

[0109]

Example 1 Using the apparatus shown in FIG. 2, a dioxin-containing liquid was subjected to wet oxidation treatment. 25mm diameter for wet oxidation,
Using a cylindrical reactor 13 having a length of 2500 mm, 1 liter of a catalyst comprising titanium-iron oxide and platinum (0.3% by mass as Pt) was filled as a solid catalyst (pellet). Waste incinerator smoke drainage was used as the dioxin-containing liquid. The concentration of dioxins in the dioxin-containing liquid subjected to the treatment was 120 ng / liter,
The EQ was 1.0 ng / liter. The liquid was supplied through a liquid supply line 6 and fed under pressure at a flow rate of 1 liter / h by a pump 7, heated to 165 ° C. by a heat exchanger 11 and a heater 12, and supplied from the bottom of the reactor 13. Air is supplied from the oxygen-containing gas supply line 8 and the pressure is increased by the compressor 9.
The flow rate was controlled by an oxygen-containing gas flow rate control valve (not shown) so that the flow rate became 1 liter / hr, and the gas was mixed into the liquid before the heat exchanger 11. In the reactor 13, the processing was performed in a gas-liquid upward parallel flow. In the reactor 13, the liquid was kept at 165 ° C. using an electric heater (not shown), and wet oxidation treatment of dioxins was performed. The liquid treated in the reactor 13 (hereinafter abbreviated as “treatment liquid”) was sent to a gas-liquid separator 16 via a heat exchanger 11 and a cooler 15 via a treatment liquid line 14 to be separated into gas and liquid. In the gas-liquid separator 16, the liquid level was detected by the liquid level controller LC, the liquid level control valve 18 was controlled so as to maintain a constant liquid level, and the liquid was discharged from the line 17. The pressure control valve 22 detects the pressure with a pressure controller PC and outputs a pressure of 0.9 MPa (Gauge).
The pressure was controlled so as to be maintained. The TEQ of the liquid discharged from the line 17 was 0.009 ng / liter, and the dioxin concentration was 0.8 ng / liter.

Examples 2 to 17 The dioxin-containing liquid was subjected to wet oxidation under the same conditions as in Example 1 except that the catalyst was changed.

Example 2 A catalyst comprising a titanium-iron oxide and manganese (5% by mass as MnO ₂ ) was used as a solid catalyst (pellet).

Example 3 As a solid catalyst (pellet), a catalyst comprising an oxide of titanium-iron and cobalt (5% by mass as CoO) was used.

Example 4 As a solid catalyst (pellet), a catalyst comprising an oxide of titanium-iron and nickel (5% by mass as NiO) was used.

Example 5 As a solid catalyst (pellet), a catalyst composed of a titanium-iron oxide and cerium (5% by mass as CeO ₂ ) was used.

Example 6 As a solid catalyst (pellet), a catalyst comprising an oxide of titanium-iron and tungsten (5% by mass as WO ₃ ) was used.

Example 7 A catalyst comprising a titanium-iron oxide and copper (5% by mass as CuO) was used as a solid catalyst (pellet).

Example 8 As a solid catalyst (pellet), a catalyst comprising a titanium-iron oxide and silver (0.3% by mass as Ag) was used.

Example 9 A catalyst comprising a titanium-iron oxide and gold (0.3% by mass as Au) was used as a solid catalyst (pellet).

Example 10: Titanium-iron oxide and palladium (0.3% as Pd) were used as solid catalysts (pellets).
% By mass).

Example 11 As a solid catalyst (pellet), a catalyst comprising an oxide of titanium-iron and rhodium (0.3% by mass as Rh) was used.

Example 12: Titanium-iron oxide and ruthenium (Ru: 0.3%) were used as solid catalysts (pellets).
% By mass).

Example 13: Titanium-iron oxide and iridium (0.3 as Ir) as solid catalysts (pellets)
% By mass).

Example 14 As a solid catalyst (pellet), a catalyst composed of titanium oxide and platinum (0.3% by mass as Pt) was used.

Example 15 As a solid catalyst (pellet), a catalyst composed of an oxide of titanium-zirconium and platinum (0.3% by mass as Pt) was used.

Example 16 As a solid catalyst (pellet), a catalyst comprising an oxide of titanium-silicon and platinum (0.3% by mass as Pt) was used.

Example 17 A catalyst comprising an aluminum-silicon oxide and platinum (0.3% by mass as Pt) was used as a solid catalyst (pellet).

Example 18 Activated carbon and platinum (P
The treatment was performed under the same conditions as in Example 1 except that a solid catalyst (pellet in the form of 0.3 mass% as t) was used, the treatment temperature was set to 95 ° C., the pressure control valve was fully opened, and no pressure was applied. .

Comparative Example 1 The procedure of Example 1 was repeated, except that no catalyst was used. Table 1 shows the results of Examples 1 to 18 and Comparative Example 1.

[0129]

[Table 1]

Example 19 Dioxin-containing soil was treated using the apparatus shown in FIG. Dioxin-containing soil to be treated was obtained by adding waste incineration ash to soil collected in a waste incineration facility. Dioxin concentration is 810n
g / g (5.2 ng-TEQ / g). The organic halogen compound-containing soil was supplied from the soil supply line 1 to the flotation device 2 with stirring at 0.03 kg / hr. 0.3 MPa (Ga) from the extraction liquid supply line 21.
under pressure of 3 liters / hr. The soil from which dioxins had been removed was discharged from the soil discharge line 3. Soil discharge line 3
Of dioxins in soil discharged from the sea is 72 ng / g
(460 pg-TEQ / g). Flotation device 2
The dioxin-containing liquid generated in the above is extracted liquid extraction line 4
To the supply tank 5. The dioxin concentration in the liquid was 7400 ng / liter (69 ng-TEQ /
Liters). The dioxin-containing liquid in the supply tank 5 is supplied to a pump 7 through a liquid supply line 6 and supplied to a pump 7.
The pressure was fed at a flow rate of liter / hr. On the other hand, after the air from the oxygen-containing gas supply line 8 was pressurized by the compressor 9, it was mixed with the dioxin-containing liquid at a flow rate of 100 Nl / hr. The gas-liquid mixture is heated by a heat exchanger 11 through a liquid supply line 6a, further heated by a heater 12, and then heated by a wet oxidation reactor 13 filled with a catalyst.
Introduced from the bottom. As a catalyst, 3 liters of a solid catalyst in the form of pellets (0.3% by mass of platinum) composed of titanium-iron oxide and platinum were used. In the reactor 13, the processing was performed in a gas-liquid upward parallel flow. In the reactor 13, the temperature of the solution was kept at 165 ° C. using an electric heater (not shown), and wet oxidation treatment of dioxins was performed. The liquid (hereinafter abbreviated as “treatment liquid”) treated in the reactor 13 passes through the treatment liquid line 14 and passes through the heat exchanger 11 and the cooler 15.
And sent to the gas-liquid separator 16 for gas-liquid separation. In the gas-liquid separator 16, the liquid level was detected by the liquid level controller LC, the liquid level control valve 18 was controlled so as to maintain a constant liquid level, and the liquid was discharged from the line 17. The pressure control valve 22 detects the pressure with a pressure controller PC and outputs a pressure of 0.9 MPa (G
aug) was controlled to be maintained. Line 17
The TEQ of the solution discharged from was 0.7 ng / liter, and the dioxin concentration was 91 pg / liter.

Example 20 The wastewater containing dioxins was treated continuously for 100 hours by using the wet oxidation treatment apparatus shown in FIG. 2, and the solid matter produced thereby was washed by the washing method of the present invention. The treatment was performed continuously for 6 hours. The detailed experimental methods and results are described below. A reactor 13 filled with 1 liter of a catalyst (0.3 mass% as Pt) composed of a titanium-iron oxide and platinum as a solid catalyst (pellet) was used. Waste incinerator smoke drainage was used as the dioxin-containing liquid. The dioxin-containing solution subjected to the treatment had a dioxin concentration of 110 ng / liter,
The EQ was 0.9 ng / l and the calcium concentration was 160 mg / l. This dioxin-containing liquid was supplied from the liquid supply line 6 to the pump 7 at a rate of 1 liter / liter.
The pressure was fed at a flow rate of hr. On the other hand, air was supplied from the oxygen-containing gas supply line 8 and pressurized by the compressor 9, and then mixed with the dioxin-containing wastewater at a flow rate of 30 Nl / hr. The gas-liquid mixture was heated by the heat exchanger 11 via the liquid supply line 6a, and further heated by the heater 12, and introduced into the wet oxidation reactor 13 filled with the catalyst. In the reactor 13, the processing was performed in a gas-liquid upward co-current flow. In the reactor 13, the liquid was kept at 165 ° C. by using an electric heater (not shown), and a wet oxidation treatment of dioxins was performed. The liquid treated in the reactor 13 (hereinafter abbreviated as “treatment liquid”) is supplied to the treatment liquid line 1.
After passing through No. 4, it was sent to a gas-liquid separator 16 via a heat exchanger 11 and a cooler 15 to perform gas-liquid separation. In the gas-liquid separator 16, the liquid level was detected by the liquid level controller LC, the liquid level control valve 18 was controlled so as to maintain a constant liquid level, and the liquid was discharged from the line 17. The pressure control valve 22 detects the pressure with a pressure controller PC and controls the pressure to maintain a pressure of 0.9 MPa (Gauge).

After the above wet oxidation treatment, the wet oxidation reactor 13
A large amount of solid matter adhered to the surface of the catalyst charged in the first step. This was analyzed by an electron probe microanalyzer, and as a result, it was found to be a solid mainly composed of calcium. Subsequently, the catalyst to which the solids adhered was subjected to the washing treatment of the wet oxidation treatment apparatus by the washing method of the present invention as follows. The alkali cleaning liquid was fed from the liquid supply line 6 by the pump 7 at a flow rate of 0.5 liter / hr. 10 for alkaline cleaning solution
A 0 g / liter aqueous solution of sodium hydroxide was used. On the other hand, air was introduced from the oxygen-containing liquid supply line 8 and pressurized by the compressor 9, and then mixed with the above alkaline cleaning liquid at a flow rate of 0.05 Nm ³ / hr. This gas-liquid mixture was heated by the heat exchanger 11 through the liquid supply line 6a, further heated to 165 ° C. by the heater 12, and introduced into the wet oxidation reactor 13 from the bottom. In the reactor 13, the processing was performed in a gas-liquid upward parallel flow. In the reactor 13, the liquid was kept at 165 ° C. by using an electric heater (not shown), and a washing treatment of solids and the like attached to the inner surface of the reaction tube and the catalyst surface was performed. The alkaline cleaning liquid (hereinafter, abbreviated as “used cleaning liquid”) used in the reactor 13 includes:
Heat exchanger 11 and cooler 1 via treatment liquid line 14
5 to a gas-liquid separator 16 for gas-liquid separation. In the gas-liquid separator 16, the liquid level is detected by the liquid level controller LC.
The liquid level control valve 18 was controlled so as to maintain a constant liquid level, and the liquid was discharged from the liquid discharge line 17. Pressure control valve 2
2 is a pressure controller PC for detecting pressure, 0.9M
Control was performed so as to maintain the pressure of Pa (Gauge). Subsequently, the above-described wet oxidation treatment of the dioxin-containing liquid was performed under the same conditions, and the cleaning treatment of the present invention was repeated twice under the same conditions as above. as a result,
The wet oxidation treatment apparatus could be operated without blocking, and no solid matter was particularly adhered to the catalyst surface after the washing treatment.

Example 21 The treatment was performed under the same conditions as in Example 20 except that the target wastewater and the catalyst for the wet oxidation treatment were changed. As the dioxin-containing wastewater to be treated, aluminum is 110m
A waste incinerator smoke drain containing g / liter and containing dioxins was used. As the catalyst, 1 liter of a solid catalyst (0.3% by mass of platinum) composed of titanium-zirconium oxide and platinum was used. After the wet oxidation treatment of the dioxin-containing liquid, a large amount of solids adhered to the catalyst surface. This was analyzed with an electron probe microanalyzer, and as a result, it was found that aluminum was the main component. As a result of performing the cleaning treatment using the cleaning method of the present invention in the same manner as in Example 20, no solid matter was particularly adhered to the catalyst surface.

Example 22 Processing was performed under the same conditions as in Example 20 except that no air was supplied during the cleaning treatment, the concentration of sodium hydroxide in the cleaning liquid was 20 g / liter, and the cleaning time was 40 hours. Was done. Although a large amount of solid matter adhered to the catalyst surface after the wet oxidation treatment of the dioxin-containing liquid, the washing treatment was performed using the washing method of the present invention in the same manner as in Example 20. The solid matter adhering to the catalyst surface could be almost removed.

Example 23 A cleaning solution containing 600 mg / L of iron ions and 100 g / L of hydrochloric acid was used, and the cleaning temperature was 90 ° C.
The treatment was carried out under the same conditions as in Example 20, except that the pressure during washing was normal pressure. A large amount of solids containing calcium as a main component adhered to the surface of the catalyst after the wet oxidation treatment as in Example 20, but the catalyst was cleaned using the cleaning method of the present invention in the same manner as in Example 20. As a result, the solid matter adhering to the catalyst surface before the cleaning treatment could be almost removed.

Example 24 A treatment was carried out under the same conditions as in Example 23 except that a 200 g / L sulfuric acid aqueous solution containing 0.8 g / L copper ions was used as a cleaning solution. As in Example 23, a large amount of solid containing calcium as a main component adhered to the catalyst surface after the wet oxidation treatment. On the other hand, no solid matter was particularly adhered to the catalyst surface after the washing treatment.

Example 25 A process was performed under the same conditions as in Example 23 except that no air was supplied during the cleaning process. As a result, the solid matter that had adhered to the catalyst surface before the cleaning treatment remained slightly after the cleaning treatment, but did not hinder the continuation of the wet oxidation treatment.

Comparative Example 2 A dioxin-containing liquid was subjected to wet oxidation under the same conditions as in Example 20 except that the cleaning treatment of the present invention was not performed. (Only the wet oxidation treatment was performed continuously.) As a result, the clogging occurred in the wet oxidation reactor 13 after about 300 hours, and the wet oxidation treatment could not be continued. When the wet oxidation reactor 13 was opened, a large amount of solids had adhered to the catalyst surface and the inner wall of the reactor. This was analyzed with an electron probe microanalyzer, and as a result, it was found that the main component was calcium.

[0139]

According to the method of the present invention, dioxins contained in a liquid can be efficiently converted into carbon dioxide, water, dissolved salts and ash, etc., without producing any harmful substances. It is possible to make it harmless.

When the cleaning method of the present invention is used, the dioxin-containing liquid adheres to the processing apparatus after the wet oxidation treatment.
Since the generated solids and the like can be efficiently cleaned, the clogging of the processing apparatus can be prevented.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a processing apparatus according to the present invention.

FIG. 2 is an embodiment of a processing apparatus according to the present invention.

FIG. 3 is an embodiment of a flotation device according to the present invention.

[Explanation of symbols]

 1. Soil supply line 2. 2. Flotation device Soil discharge line 4. Extract drain line 5. Supply tank 6. Liquid supply line 6a. Liquid supply line 7. Pump 8. 8. Oxygen-containing gas supply line Compressor 11. Heat exchanger 12. Heater 13. Reactor 14. Processing liquid line 15. Cooler 16. Gas-liquid separator 17. Liquid discharge line 18. Liquid level control valve 19. Gas discharge line 20. Liquid tank 21. Extraction liquid supply line 22. Pressure control valve LC. Liquid level controller PC. Pressure controller

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) B01J 23/755 B01J 23/74 301M 23/889 311M 23/85 321M 23/89 23/84 311M B09B 3 / 00 B09B 3/00 304G B09C 1/02 304K 1/08 (72) Inventor Kiichiro Mitsui 992, Nishioki, Okihama-shi, Aboshi-ku, Himeji-shi, Hyogo F-term in Nippon Shokubai Co., Ltd. 4D004 AA36 AA41 AB06 AB07 CA36 CB02 CB31 CC01 CC02 CC09 CC12 DA02 DA07 DA10 4D050 AA20 AB19 BB01 BB02 BC01 BC02 BC05 BC06 BC07 BD02 BD03 BD06 CA05 4D056 AB17 AC06 AC22 BA16 CA07 CA17 CA21 CA22 CA31 CA33 CA34 CA37 CA39 DA01 DA02 4G069 AA03 BA01A BABA BA02B BA20B BB02A BB02B BB06A BB06B BC31A BC31B BC32A BC32B BC33A BC33B BC43A BC43B BC60A BC60B BC62A B C62B BC66A BC66B BC67A BC67B BC68A BC68B BC70A BC70B BC71A BC71B BC72A BC72B BC74A BC74B BC75A BC75B CA04 CA05 CA07 CA10 CA11 CA19 DA06 EA02Y

Claims (6)

[Claims] 1. A method for decomposing dioxins and / or coplanar-PCB in a liquid containing dioxins and / or coplanar-PCB, the method comprising the steps of: A method for treating dioxins and / or coplanar-PCB, comprising oxidizing or decomposing dioxins and / or coplanar-PCB contained in the liquid under a pressure at which the liquid maintains a liquid phase. 2. The method according to claim 1, wherein the liquid is a liquid obtained by contacting soil or ash containing dioxins and / or coplanar PCB with an extraction liquid. 3. The method according to claim 1, wherein the contacting step comprises introducing soil or ash containing dioxins and / or coplanar PCB into the extraction solution to obtain dioxins and / or coplanar.
3. The method of claim 2, wherein a contacting method is used to separate the PCB from soil or ash. 4. The catalyst according to claim 1, wherein the catalyst is at least one selected from titanium, silicon, aluminum, zirconium, manganese, iron, cobalt, nickel, cerium, tungsten, copper, silver, gold, platinum, palladium, rhodium, ruthenium and iridium. The method according to any one of claims 1 to 3, which is a catalyst containing the above element and / or activated carbon. 5. A method for cleaning a wet oxidation treatment apparatus used for decomposing dioxins and / or coplanar-PCB in a liquid containing dioxins and / or coplanar-PCB, wherein an alkali cleaning liquid or an acid cleaning liquid is provided in the apparatus. A method for cleaning a wet oxidation treatment apparatus, comprising: introducing and cleaning under a pressure at which the cleaning liquid maintains a liquid phase. 6. The method according to claim 5, wherein the wet oxidizing apparatus is a wet oxidizing apparatus incorporating at least one of a catalyst, an adsorbent, and a filler.