JP2003175392A - Method and system for hydrothermal oxidation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for hydrothermal oxidation for treating liquid containing a highly concentrated ions or salts. <P>SOLUTION: In the method of hydrothermal oxidation, a to-be-treated liquid is filtered, and solid and suspended matters are removed in a step S1. The treated liquid is heated to a predetermined temperature, e.g. 40°C in order to improve efficiency of electrodialytic treatment in a step S2, and the liquid is subjected to the electrodialysis treatment to reduce as far as possible inorganic ions in the liquid containing organic substances in a step S3. In a step S4, dilute solution of the liquid is subjected to a supercritical-water oxidation treatment of one kind of hydrothermal oxidation treatment. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for hydrothermally oxidizing a liquid to be treated containing inorganic ions and organic matter, and a hydrothermal oxidation system for carrying out the method, and more specifically, to a relatively large amount of inorganic ions. The present invention relates to a hydrothermal oxidation method for a liquid to be treated and a hydrothermal oxidation system.

[0002]

2. Description of the Related Art With increasing awareness of the environment, waste liquids containing harmful wastes, particularly waste liquids containing harmful persistent organic substances, etc., are required to completely decompose and discharge harmful substances. Therefore, high-temperature high-pressure water, for example, temperature 180 ℃
As described above, a hydrothermal oxidation method using hot water having a pressure of 1 MPa or more,
In particular, it has been attempted to apply a supercritical water oxidation reaction, which has a high oxidative decomposition ability of organic substances, utilizing the high reactivity of supercritical water, to the treatment of waste liquid. In the supercritical water oxidation reaction, harmful and hardly decomposable organic substances, which are difficult to decompose by conventional techniques, such as PCB (polychlorinated biphenyl), dioxin, and organic chlorine-based solvent are oxidatively decomposed to generate carbon dioxide, It can be converted to innocuous products such as nitrogen, water, inorganic salts.

The supercritical water oxidation device is a device for decomposing organic substances by utilizing the high reactivity of supercritical water. For example, toxic decomposition of harmful persistent organic substances into harmless carbon dioxide is performed. In order to convert it into water or to decompose a hardly decomposable high molecular compound into a useful low molecular compound, its practical application is currently being actively studied. Supercritical water is water in a supercritical state, that is, water in a state of exceeding the critical point of water, and more specifically, at a temperature of 374.1 ° C. or higher and a pressure of 22.04 MPa or higher. Says water in a certain state. Supercritical water has a high solubility to dissolve organic substances,
It is possible to completely dissolve even non-polar substances that are abundant in organic compounds, but on the contrary, the ability to dissolve inorganic substances such as metals and salts is extremely low. Further, supercritical water can be mixed with a gas such as oxygen or nitrogen at an arbitrary ratio to form a single phase.

Now, with reference to FIG. 8, a basic structure of a supercritical water oxidation apparatus for oxidatively decomposing an organic chlorine compound, which is a halogenated organic substance such as PCB or dioxin, by supercritical water reaction will be described. . FIG. 8 is a flow sheet showing the structure of a conventional supercritical water oxidation apparatus. Supercritical water oxidation device 1
Reference numeral 0 denotes an apparatus for treating a liquid to be treated containing an organic chlorine compound by a supercritical water reaction in the presence of supercritical water, and as shown in FIG. The pressure-resistant closed reactor 12 is provided.

Also, the supercritical water oxidation apparatus 10 is a reactor 1
As the processing fluid system 13 for causing the processing fluid to flow out from 2,
Process fluid pipe 14 connected to process fluid outlet of reactor 12
In addition, a neutralization quencher 15 for injecting an alkaline aqueous solution into the treatment fluid for rapid neutralization quenching, a cooler 16 for further cooling the treatment fluid,
A pressure control valve 18 for controlling the pressure in the reactor 12, and
A gas-liquid separator 20 that separates the processing fluid into a gas component and a liquid component is sequentially provided. The neutralization quencher 15 injects an alkaline aqueous solution into the processing fluid to neutralize hydrochloric acid and the like generated from the organic chlorine compound in the liquid to be processed in the reactor 12 by the supercritical water reaction and cool the processing fluid. .

A gas outflow pipe 22 for outflowing the separated gas component is connected to the upper part of the gas-liquid separator 20, and a liquid outflow pipe 24 for outflowing the separated liquid component is connected to the lower part. Further, a back pressure valve 26 that controls the pressure of the gas-liquid separator 20 is provided in the gas outflow pipe 22, and a liquid level control that controls the liquid level of the gas-liquid separator 20 by adjusting the outflow flow rate in the liquid outflow pipe 24. A valve 27 is provided.

The supercritical water oxidation apparatus 10 is a supply system for supplying the reactants for the supercritical water reaction to the reactor 12.
A liquid to be treated pump 28 and an air compressor 30 are provided, and a liquid to be treated containing an organic chlorine compound is fed into the reactor 12 via a liquid pipe 32 to be treated and connected to the liquid pipe 32 to be treated. Air as an oxidant is fed into the reactor 12 together with the liquid to be treated through the air feed pipe 34. Further, in order to maintain the supercritical water reaction in the reactor 12, a makeup water pipe 38 for adding makeup water or the like to the treatment liquid pipe 32 is connected to the treatment liquid pipe 32.

The supercritical water oxidation apparatus 10 is capable of almost completely oxidizing and decomposing the organic chlorine compound in the liquid to be treated so that the concentration of the organic chlorine compound in the liquid to be treated becomes equal to or lower than the reference value.
For example, when treating PCB or dioxin, the supercritical water oxidation apparatus 10 is 3 μg based on the PCB concentration of the treatment liquid.
/ Liter or less, and the dioxin concentration of the treatment liquid can be set to 10 pg TEQ / liter or less of the standard.

[0009]

The waste liquid discharged from laboratories, factories and the like often contains a large amount of various kinds of inorganic substances as ions or compounds.
However, in the supercritical water region in the reactor of the supercritical water oxidation device, NaCl, Na ₂ SO ₄ , CaSO ₄ , CaCO ₃
Since the solubility of salts such as is extremely reduced, when a liquid to be treated containing a high concentration of inorganic substances, for example, a waste liquid is treated with a supercritical water oxidation device, salts are deposited on the inner wall of the reactor. As a result, in the case of a vessel type reactor, there is a problem that the inflow nozzle of the liquid to be treated, the outflow nozzle of the treatment liquid, etc., and in the case of the tube type reactor, the reaction tube itself is clogged immediately after the start of operation. It was For example, when Ca ions are contained in the liquid to be treated, CaCO ₃ , CaSO _4, etc. are deposited on the inner wall of the reactor. In this case, it is difficult to perform stable supercritical water oxidation treatment on waste liquid containing inorganic ions for a long period of time.

Therefore, although various attempts have been conventionally made to remove inorganic ions or salts in hydrothermal oxidizers for treating wastes and waste liquids containing inorganic ions, a satisfactory range has not yet been reached. Not not. The hydrothermal oxidizer used herein includes supercritical water and has a temperature of 180 ° C.
The above means an apparatus for oxidatively decomposing organic substances in a reactor capable of holding a fluid having a pressure of 1 MPa or more. Therefore, an object of the present invention is to provide a hydrothermal oxidation method and a hydrothermal oxidation system for treating a liquid to be treated containing a high concentration of inorganic ions or salts.

[0011]

As described above, the fact that a reaction tube or a nozzle of a reactor of a hydrothermal oxidizer, in particular a supercritical water oxidation unit, is clogged is due to a salt having a solubility higher than that of a salt of supercritical water. Is present in the liquid to be treated or the salt is dissolved. Therefore, the present inventor considers that it is necessary to reduce the concentration of each salt in the liquid to be treated as much as possible, and as a pretreatment of the hydrothermal oxidation treatment, the liquid to be treated is previously desalted or inorganic The idea was to perform a separation process. The present inventor has applied the electrodialysis method and the membrane separation method as the inorganic ion separation treatment, and invented the present invention after various experiments.

In order to achieve the above object, the method for hydrothermal oxidation of a liquid to be treated (hereinafter referred to as the first invention method) according to the present invention contains an inorganic ion and an organic substance based on the above findings. A method for hydrothermal oxidation of a liquid to be treated, wherein the liquid to be treated is subjected to an inorganic ion separation treatment to remove inorganic ions from the liquid to be treated, an organic substance is contained, and the concentration of the diluted inorganic ion is reduced. It is characterized by having an inorganic ion separation step of preparing a treatment liquid and a hydrothermal oxidation step of decomposing organic matter by subjecting a diluted liquid to be treated to hydrothermal oxidation treatment.

Another method for hydrothermally oxidizing a liquid to be treated according to the present invention (hereinafter referred to as a second invention method) is a method for hydrothermally oxidizing a liquid to be treated containing a halogenated organic substance. By injecting an alkaline solution into the liquid to be treated and performing heat treatment, a step of isolating halogen as an inorganic ion from the halogenated organic substance, and a liquid containing the isolated inorganic ions are subjected to an inorganic ion separation treatment. In addition to removing inorganic ions from the liquid to be treated, an inorganic ion separation step of preparing a diluted liquid to be treated containing an organic substance and having a reduced inorganic ion concentration, and subjecting the diluted liquid to be hydrothermally oxidized, And a hydrothermal oxidation step of decomposing organic substances.

The second method of the present invention is most suitable when the liquid to be treated is a waste liquid containing halogenated organic matter such as PCB having a relatively high concentration. In the inorganic ion separation step of the first and second invention methods, the concentration of inorganic ions in the diluted liquid to be treated is reduced as much as possible.

Preferably, a concentration step is provided between the inorganic ion separation step and the supercritical water oxidation step to increase the organic matter concentration by concentrating the diluted liquid to be treated. Thereby, even when the liquid to be treated having a low organic matter concentration is hydrothermally oxidized, the hydrothermal oxidation treatment can be performed without injecting the auxiliary fuel into the reactor.

In the inorganic ion separation step, a membrane separation treatment for removing inorganic ions in the liquid to be treated is performed. Alternatively, an inorganic ion separation treatment by electrodialysis is applied to the liquid to be treated, the inorganic ions are transferred, and a concentrated liquid in which the concentration of the inorganic ions is higher than the original liquid to be treated is discharged, while containing an organic substance and being inorganic. A diluted liquid to be treated in which the ion concentration is reduced as much as possible is prepared.

When the hydrothermal reaction step is a supercritical water oxidation step, in the inorganic ion separation step by the electrodialysis method, the concentrated liquid is further separated into an acid component and an alkaline component, and the supercritical water oxidation step is carried out from the reactor. In order to rapidly quench and neutralize the processing fluid flowing out, the separated alkaline component may be injected into the processing fluid. It is effective in treating a liquid to be treated having a high concentration of an organic chlorine compound which is a halogenated organic substance. Also,
By providing the step of heating the liquid to be treated before the inorganic ion separation step by the electrodialysis method, the efficiency of the electrodialysis treatment can be improved, the treatment time can be shortened, and the required electricity amount can be reduced. Further, before the inorganic ion separation step by the electrodialysis method, a removal step for removing solids and suspensions in the liquid to be treated is provided to prevent early clogging of the ion exchange membrane of the electrodialysis apparatus. be able to.

The electrodialysis method is to feed a liquid to be treated between a cation exchange membrane and an anion exchange membrane, and to energize electrodes provided outside each of the cation exchange membrane and the anion exchange membrane. By forming an electric field by moving the inorganic ions in the liquid to be treated, a concentrated liquid having a high concentration of inorganic ions,
This is a technique of separating the liquid to be treated into a diluted liquid to be treated in which the concentration of inorganic ions is low and organic substances remain, and the inorganic substances can be removed preferentially as a pretreatment of the liquid to be treated.
At that time, an organic substance or the like to be treated by hydrothermal oxidation remains on the side of the diluted liquid to be treated. Although low-molecular-weight organic acids and the like may migrate to the concentrated liquid side, low-molecular-weight organic substances that pass through the ion exchange membrane are not harmful substances that are subject to supercritical water oxidation. .

When applying the method of the present invention, there are no restrictions on the composition and concentration of inorganic ions and organic substances.

A hydrothermal oxidation system for carrying out the method of the present invention is a hydrothermal oxidation system for hydrothermally oxidizing a liquid to be treated containing an inorganic ion and an organic substance, wherein the liquid to be treated is subjected to an inorganic ion separation treatment, An inorganic ion separator that removes inorganic ions from the liquid to be treated and that contains an organic substance, and prepares a diluted liquid to be treated with a reduced concentration of inorganic ions, and a hydrothermal oxidation treatment is applied to the diluted liquid to be treated, and an organic substance And a hydrothermal oxidizer for decomposing.

When the organic substance contains a halogenated organic substance,
A dehalogenation device for isolating halogen as an inorganic ion from a halogenated organic substance by injecting an alkaline solution into a liquid to be treated and performing heat treatment may be provided upstream of the inorganic ion separation device. Thereby, the liquid to be treated having a high halogenated organic substance concentration can be treated.

As the inorganic ion separator, a membrane separator for separating inorganic substances and organic substances in the liquid to be treated is provided. As the membrane separation device, for example, a membrane separation device using an ultrafiltration membrane, a loose reverse osmosis membrane or the like can be used.

Alternatively, by providing an electrodialysis device as an inorganic ion separating device and subjecting the liquid to be treated by the electrodialysis method, the inorganic ions are transferred and the concentration of the inorganic ions becomes higher than that of the original liquid to be treated. While diluting the concentrated liquid, a diluted liquid to be treated containing an organic substance and having the inorganic ion concentration reduced as much as possible is prepared. The electrodialyzer is provided upstream of the liquid pump for treating the diluted liquid to be heated up to the reaction pressure of hydrothermal oxidation in order to reduce the operating pressure to make the device economical.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings, in which a supercritical water oxidation step is used as a hydrothermal oxidation step. explain. Embodiment Example 1 of Supercritical Water Oxidation Method This embodiment example is an example of an embodiment of a supercritical water oxidation method for a liquid to be treated according to the first invention method, and FIG. It is a flowchart which shows a procedure. First,
As shown in FIG. 1, in step S ₁ , the liquid to be treated is filtered to remove solids and suspended matter in the liquid to be treated. In step S ₂ , the liquid to be treated is heated to a predetermined temperature, for example 40 ° C., in order to increase the efficiency of the electrodialysis treatment. Next, in step S _3, performs electrodialysis treatment, an inorganic ion of the treatment solution containing an organic material is reduced as much as possible, the inorganic ion concentration is extremely low, salt supercritical water process If the concentration does not precipitate, for example, NaCl ions,
A diluted solution to be treated of 100 mg / L or less is prepared. Subsequently, in step S _4, subjected to supercritical water treatment diluting liquid to be treated.

Embodiment 2 of Supercritical Oxidation Method This embodiment example is another example of the embodiment of the supercritical water oxidation method for the liquid to be treated according to the second invention method, and FIG. 6 is a flowchart illustrating a procedure of an example embodiment method. First, as shown in FIG. 2, in step S ₁ , the liquid to be treated is filtered to remove solids and suspensions in the liquid to be treated. In step S _2, by heating by injecting an alkaline solution into the liquid to be treated, performing the dehalogenation step of isolated halogens from halide organic as inorganic ions. Next, in step S _3, performs electrodialysis treatment, containing organic substances, and inorganic ion concentration is extremely low, the concentration does not salt supercritical water process precipitation, for example N
If it is aCl ion, a diluted solution to be treated of 100 mg / L or less is prepared. Subsequently, in step S _4, subjected to supercritical water treatment diluting liquid to be treated.

In Embodiments 1 and 2, when the concentration of organic substances in the liquid to be treated is low, a concentration step for concentrating the diluted liquid to be treated is provided between the electrodialysis step and the supercritical water oxidation step. Thus, even when the liquid to be treated having a low organic matter concentration is subjected to supercritical water oxidation, supercritical water oxidation can be performed without injecting the auxiliary fuel into the reactor in the supercritical water oxidation step.

Example 1 of Embodiment of Supercritical Water Oxidation System This example of the embodiment is an example of the embodiment of the supercritical water oxidation system according to the present invention, in which the electrodialysis method is used as the pretreatment of the liquid to be treated. Here is an example. FIG. 3 is a flow sheet showing the configuration of the supercritical water oxidation system of this embodiment,
FIG. 4 is a schematic diagram showing the configuration of the electrodialysis device. As shown in FIG. 3, the supercritical water oxidation system 40 of the present embodiment is an electric device provided on the suction side of the above-mentioned supercritical water oxidation apparatus 10 and the liquid to be treated pump 28 of the supercritical water oxidation apparatus 10. The liquid to be treated is provided with a dialysis device 42 and a microfiltration membrane to perform membrane separation, and solids and suspensions (hereinafter, SS (Suspended)
And a microfiltration device 44 for sending a liquid to be treated having a low concentration of Solid)) to the electrodialysis device 42. Microfiltration device 4
A device 4 is capable of reducing the SS concentration of the liquid to be treated from about 50 ppm to about 2 ppm, for example.

The electrodialysis device 42, as shown in FIG.
An anode 56 is provided at one end of the container 48, and a cathode 58 is provided at the other end of the container 48. The anion exchange membrane 50 and the cation exchange membrane 52 are alternately separated and faced from the anode side toward the cathode side. A large number of small chambers 54 are formed by partitioning the inside of the container 48 with the anion exchange membrane 50 and the cation exchange membrane 52. The anion exchange membrane 50 at one end of the container and the small chamber 54A between the container wall and the anode 5
6 is provided, and the cation exchange membrane 52 at the other end of the container is provided.
A cathode 58 is provided in a small chamber 54B between the container wall and the container.

The diluted liquid to be treated is supplied to the inlet of the small chamber 54C having the anion exchange membrane 50 on the anode side and the cation exchange membrane 52 on the cathode side, and becomes a diluted liquid to be treated having a low salt concentration. The diluted liquid to be treated flows out from the outlet of the small chamber 54C.
The cations in the diluted liquid to be treated move toward the cathode, and the anions move toward the anode. Further, the concentrated liquid is supplied to the inlet of the small chamber 54D having the cation exchange membrane 52 on the anode side and the anion exchange membrane 50 on the cathode side, and becomes a concentrated liquid having a higher salt concentration, and then from the outlet of the small chamber 54D. Concentrated liquid flows out. Cations pass through the cation exchange membrane 52, but do not pass through the anion exchange membrane 50. On the other hand, anions pass through the anion exchange membrane 50, but do not pass through the cation exchange membrane 52. As a result, the concentration of anions and cations in the diluted liquid to be treated in the small chamber 54C decreases, and the concentrations of anions and cations in the concentrated liquid in the small chamber 54D increase.

The diluted liquid to be treated flowing out from the small chamber 54C is
Diluted processed liquid intermediate tank 60 and diluted processed liquid pump 6
1 is circulated to the inlet of the small chamber 54C. Komuro 54D
The concentrate flowing out of the tank is circulated to the inlet of the small chamber 54D via the concentrate intermediate tank 62 and the concentrate pump 63.
Diluted liquid intermediate tank 60 and concentrated liquid intermediate tank 62
A part of the diluted liquid to be processed and the concentrated liquid are extracted from the above, the concentrated liquid is sent to another processing device, and the diluted liquid to be processed is sent to the supercritical water oxidation device 10 by the liquid to be processed pump 28. In addition,
A liquid corresponding to the amount of liquid extracted in this way is replenished to the diluted liquid intermediate tank 60 and the concentrated liquid intermediate tank 62.

In this embodiment, the electrodialyzer is:
For example, a Micro Acilyzer G5 type of electrodialysis device manufactured by Asahi Kasei Co., Ltd. is used. The amount of liquid to be treated is 4
It is 00 kg / day and is desalted in batch or continuous mode. The capacity of the electrodialyzer described above is such that when the salt concentration of the liquid to be treated is 2% sodium chloride, the desalination rate is 99.5%, and the concentration of sodium chloride in the liquid to be treated flowing out from the electrodialyzer 42 is 100 ppm. Yes, the time required for electrodialysis treatment is 3 hours.

When the temperature of the liquid to be treated flowing out from the electrodialysis device 42 is lowered to around 30 ° C., the temperature may be raised by a preheater (not shown) of the supercritical water oxidation device 10 if necessary. You can In the supercritical water oxidation system 40 of this embodiment, a tube reactor having an inner diameter of 10 mm and a length of 3539 mm is used as the reactor 12 of the supercritical water oxidation apparatus 10. The reaction temperature is 600 ° C., the reaction pressure is 24 MPa, and the reaction time is 1 minute.

When the salt is deposited, the salt adheres to the vessel wall in the preheater and the reactor 12, the flow path of the liquid to be treated is reduced, the pressure loss is increased, and the supercritical water oxidation treatment is further continued. It should be difficult, but the supercritical water oxidation system 4 of the present embodiment example
When 0 was used to subject a liquid to be treated having a TOC component of 10 mass% with a NaCl concentration of 100 mg / L to supercritical water oxidation, a significant increase in pressure loss occurred even after continuous operation for 300 hours. There wasn't. By subjecting the liquid to be treated having a TOC component of 10% by mass and an inorganic substance concentration of 2% to electrodialysis in the electrodialysis device 42, a supercritical water oxidation treatment is carried out to obtain the liquid to be treated in the reactor 12. TOC was below the lower limit of quantification. Therefore, it can be evaluated that the supercritical water oxidation treatment is stably performed by applying the supercritical water oxidation system 40 of the present embodiment.

Embodiment 2 This embodiment is another embodiment of the supercritical water oxidation system according to the present invention in which the electrodialysis method is used as the pretreatment of the liquid to be treated, and FIG. It is a flow sheet which shows the structure of the supercritical water oxidation system of the example 2 of a form. As shown in FIG. 5, the supercritical water oxidation system 64 of the present embodiment is implemented except that it has a heating means 66 for heating the liquid to be treated between the microfiltration device 44 and the electrodialysis device 42. It has the same configuration as the supercritical water oxidation system 40 of the first embodiment.

In this embodiment, as the heating means 66,
A heat exchanger is provided which uses a part of the processing fluid flowing out from the reactor 12 of the supercritical water oxidation apparatus 10 as a heat source. The treatment fluid heated and cooled by the heat exchanger 66 merges with the treatment fluid downstream of the cooler 16 of the supercritical water oxidation apparatus 10. The heat exchanger 66 raises the temperature of the liquid to be treated to about 40 ° C. Thereby, the electrodialysis efficiency in the electrodialysis device 42 is improved, and the time required for electrodialysis and the amount of electricity used are
Compared to the first embodiment, the number is halved.

Embodiment 3 This embodiment is another example of the embodiment of the supercritical water oxidation system according to the present invention which uses the electrodialysis method as the pretreatment of the liquid to be treated. It is a flow sheet which shows the structure of the supercritical water oxidation system of this embodiment. The supercritical water oxidation system 70 of the present embodiment example is provided with a dehalogenation device 71 for dehalogenating a halogenated organic substance and isolating halogen as an inorganic ion between the microfiltration device 44 and the electrodialysis device 42. It has the same configuration as the supercritical water oxidation system 40 of the first embodiment except that The dehalogenation device 71 is provided in the latter stage of the microfiltration device 44, and has a high-pressure pump 72 that pressurizes the microfiltered liquid to be treated, an alkali addition mechanism 73 that adds an alkali to the liquid to be treated, and a liquid to be treated. A high-temperature and high-pressure reaction tank 74 for reacting an alkali to advance the dehalogenation reaction, a cooler 75 for cooling the dehalogenated liquid to be treated to the operating temperature of the electrodialysis device 42, and an operating pressure for the electrodialysis device 42. And a pressure reducing valve 76 for reducing the pressure.

Embodiment 4 This embodiment is another example of the embodiment of the supercritical water oxidation system according to the present invention which uses the electrodialysis method as the pretreatment of the liquid to be treated, and FIG. It is a flow sheet which shows the structure of the supercritical water oxidation system of this embodiment. The supercritical water oxidation system 80 of the present embodiment is a device for supercritical water oxidation of a liquid to be treated having a low TOC concentration, and as it is, an auxiliary fuel is required for supercritical water oxidation, and therefore an electrodialysis device. 42 and the liquid to be treated pump 28 of the supercritical water oxidation apparatus 10 to evaporate the moisture of the liquid to be treated,
Supercritical water oxidation system 64 of Embodiment 2 except that an evaporative concentrator 82 for concentrating OC components is provided.
It has the same configuration as.

The evaporative concentrator 82 is equipped with an evaporating can and uses, for example, the treatment fluid flowing out from the reactor 12 as a heat source to evaporate the water in the liquid to be treated and electrodialyze it by the electrodialysis device 42. The organic substance concentration of the liquid to be treated can be concentrated to 5 times the original concentration. In the present embodiment example, TO
The liquid to be treated having a low C concentration of about 1% is electrodialyzer 42.
After electrodialyzing at, the TOC concentration becomes about 5% by concentrating the organic substance concentration of the liquid to be treated 5 times, so that supercritical water oxidation can be performed without auxiliary fuel.

In the present embodiment, the desalted liquid to be treated is uniformly evaporated and concentrated. Therefore, when the TOC concentration becomes about 5%, the salt concentration of the liquid to be treated also becomes higher than that of the liquid to be treated which is not evaporated and concentrated. It will be about 5 times. Therefore, when concentrating the liquid to be treated by evaporation, the concentration of sodium chloride after evaporation is 100 mg.
It is preferable to reduce the inorganic ion concentration of the liquid to be treated in the electrodialysis device 42 in advance so that it becomes / L.

Embodiment 5 This embodiment is another example of the embodiment of the supercritical water oxidation system according to the present invention which uses the electrodialysis method as the pretreatment of the liquid to be treated. The supercritical water oxidation system of the present embodiment is an apparatus for processing a liquid to be treated containing a large amount of organic chlorine compounds as organic matter, and except that the configuration of the electrodialysis apparatus is different, the supercritical water oxidation system of the third embodiment. It has the same configuration as the hydroxylation system 70.

In the present embodiment, instead of the electrodialysis device 42 of the third embodiment, an electrodialysis device in which a mixed membrane (bipolar membrane) is partially used as an ion exchange membrane is used to further concentrate the concentrated liquid. The component is separated into an acid component and the alkaline component is injected into the quenching neutralization section 15 of the supercritical water oxidation apparatus 10 as an alkaline aqueous solution. The separated acid component is used, for example, in an acid cleaning solution for an electrodialyzer.

The electrodialyzer is a small chamber 54D of the electrodialyzer 42 of the first embodiment, that is, a small chamber 5 having a cation exchange membrane 52 on the anode side and an anion exchange membrane 50 on the cathode side.
4D is further provided with a bipolar film as a partition. The bipolar membrane is a mixed membrane having an anion exchange membrane on the anode side and a cation exchange membrane on the cathode side,
By combining a bipolar membrane and an anion exchange membrane or combining a bipolar membrane and a cation exchange membrane, the salt can be separated into an acid component and an alkali component. An electrodialyzer equipped with a bipolar membrane is sold, for example, by Tokuyama Corporation.

[0043]

According to the method of the present invention, as a pretreatment for the hydrothermal oxidation treatment, the liquid to be treated is subjected to a desalting treatment or an inorganic ion separation treatment in advance so that the concentration of inorganic ions in the liquid to be treated can be increased. The amount of salt is prevented from precipitating in the reactor, so that the hydrothermal oxidation treatment can be stably performed for a long period of time. The supercritical water oxidation system according to the present invention realizes a system that preferably implements the method of the present invention.

[Brief description of drawings]

FIG. 1 is a flowchart showing a procedure of a method according to a first embodiment.

FIG. 2 is a flowchart showing a procedure of a method according to the second embodiment.

FIG. 3 is a flow sheet showing the configuration of the supercritical water oxidation system of Embodiment 1.

FIG. 4 is a flow sheet showing the configuration of an electrodialysis device.

FIG. 5 is a flow sheet showing the configuration of the supercritical water oxidation system of the second embodiment.

FIG. 6 is a flow sheet showing a configuration of a supercritical water oxidation system of Embodiment 3.

FIG. 7 is a flow sheet showing the configuration of the supercritical water oxidation system of Embodiment 4.

FIG. 8 is a flow sheet showing the structure of a supercritical water oxidation apparatus.

[Explanation of symbols]

10 Supercritical water oxidation equipment 12 reactor 13 Processing fluid system (first processing fluid system) 14 Processing fluid pipe 15 Neutralization quencher 16 Cooler 18 Pressure control valve 20 gas-liquid separator 22 Gas outflow pipe 24 liquid outflow pipe 26 Back pressure valve 28 Liquid to be treated pump 30 air compressor 32 Treated liquid pipe 34 Air inlet pipe 40 Supercritical Water Oxidation System of Embodiment 1 42 electrodialysis machine 44 Microfiltration device 48 containers 50 anion exchange membrane 52 Cation exchange membrane 54 small room 56 Anode 58 cathode 60 Diluted liquid intermediate tank 61 Diluted liquid pump 62 Concentrated liquid intermediate tank 63 Concentrate pump 64 Supercritical Water Oxidation System of Embodiment 2 66 heating means 70 Supercritical Water Oxidation System of Embodiment 3 71 Dehalogenation device 72 High pressure pump 73 Alkali addition mechanism 74 High temperature and high pressure reactor 75 Cooler 76 Pressure reducing valve 80 Supercritical Water Oxidation System of Embodiment 4 82 Evaporative concentrator

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C02F 1/469 C02F 11/08 11/08 C07B 35/06 C07B 35/06 C02F 1/46 103 (72) Inventor Akira Suzuki 1-2-8 Shinsuna, Koto-ku, Tokyo Organo Co., Ltd. (72) Inventor Taro Oe 1-2-8 Shinsuna, Koto-ku, Tokyo Organo Co., Ltd. F-term (reference) 4D006 GA04 GA06 GA07 GA17 HA95 JA02Z KA01 KA12 KA72 KB14 KB30 KD17 MA13 MA14 MB02 MB07 PA01 PA02 PA05 PB08 PB25 PB26 PB27 PB70 4D050 AA12 AB07 AB19 AB31 BB01 BC01 BC02 BD02 BD06 BD01 BE01 4D059 DA01 BE01 4D059 AA18 BC01 CA13 CA15 4D059 DA01 EA09 FA01 FA09 FA11 FA16 4H006 AA05 AC13 BA69 BA91 BE10 BE11

Claims (15)

[Claims] 1. A method for hydrothermally oxidizing a liquid to be treated containing an inorganic ion and an organic matter, wherein the liquid to be treated is subjected to an inorganic ion separation treatment to remove the inorganic ion from the liquid to be treated and to contain the organic substance. In addition, it has an inorganic ion separation step of preparing a diluted solution to be treated with a reduced concentration of inorganic ions, and a hydrothermal oxidation step of decomposing organic matter by subjecting the diluted solution to hydrothermal oxidation treatment. Hydrothermal oxidation method. 2. A method for hydrothermally oxidizing a liquid to be treated containing a halogenated organic substance, comprising injecting an alkaline solution into the liquid to be treated and heat-treating the halogenated organic substance to convert halogen into inorganic ions. The step of separating and the treatment liquid containing the isolated inorganic ions are subjected to an inorganic ion separation treatment to remove the inorganic ions from the treatment liquid, and at the same time, the diluted treatment liquid containing an organic substance and having a reduced concentration of inorganic ions. A hydrothermal oxidation method comprising: an inorganic ion separation step of preparing a treatment liquid; and a hydrothermal oxidation step of decomposing organic matter by subjecting a diluted liquid to be treated to hydrothermal oxidation treatment. 3. The hydrothermal process according to claim 1, further comprising a concentration process for concentrating the diluted liquid to be treated to increase the concentration of organic substances between the inorganic ion separation process and the hydrothermal oxidation process. Oxidation method. 4. The hydrothermal oxidation method according to claim 1, wherein in the inorganic ion separation step, a membrane separation treatment for removing inorganic ions in the liquid to be treated is performed. . 5. In the inorganic ion separation step, by subjecting the liquid to be treated to a treatment by an electrodialysis method, the inorganic ions are transferred and the concentrated liquid in which the concentration of the inorganic ions is higher than the original liquid to be treated flows out. On the other hand, the hydrothermal oxidation method according to any one of claims 1 to 3, wherein a diluted liquid to be treated containing an organic substance and having a reduced inorganic ion concentration is prepared. 6. In the inorganic ion separation step by electrodialysis, the concentrated solution is further separated into an acid component and an alkaline component, and the separation is performed in order to rapidly quench and neutralize the treated fluid flowing out from the reactor in the hydrothermal oxidation step. The hydrothermal oxidation method according to claim 5, wherein the alkaline component is injected into the treatment fluid. 7. The hydrothermal oxidation method according to claim 5, further comprising a step of heating the liquid to be treated before the inorganic ion separation step by the electrodialysis method. 8. The method according to claim 5, further comprising a removal step of removing solids and suspensions in the liquid to be treated before the inorganic ion separation step by the electrodialysis method. The hydrothermal oxidation method according to item 1. 9. A hydrothermal oxidation system for hydrothermally oxidizing a liquid to be treated containing inorganic ions and organic matter, wherein the liquid to be treated is subjected to an inorganic ion separation treatment to remove the inorganic ions from the liquid to be treated. It has an inorganic ion separation device that prepares a diluted solution to be treated that contains organic matter and has a reduced concentration of inorganic ions, and a hydrothermal oxidation device that decomposes the organic matter by subjecting the diluted solution to hydrothermal oxidation treatment. A hydrothermal oxidation system characterized in that 10. By injecting an alkaline solution into the liquid to be treated upstream of the inorganic ion separator and performing heat treatment,
The hydrothermal oxidation system according to claim 9, further comprising a dehalogenation device for isolating halogen as an inorganic ion from a halogenated organic substance. 11. The hydrothermal system according to claim 9, further comprising a concentrating device for concentrating the diluted liquid to be treated to increase the concentration of organic substances between the inorganic ion separating device and the hydrothermal oxidizing device. Oxidation system. 12. The hydrothermal oxidation system according to claim 9, further comprising a membrane separator for separating inorganic ions in the liquid to be treated as the inorganic ion separator. . 13. An electrodialysis device as an inorganic ion separator is provided, and by subjecting a liquid to be treated to a treatment by an electrodialysis method, the inorganic ions are transferred and the concentration of the inorganic ions becomes higher than that of the original liquid to be treated. The hydrothermal solution according to any one of claims 9 to 11, characterized in that a diluted solution to be treated is prepared which contains an organic substance and has a reduced inorganic ion concentration while allowing the concentrated solution to flow out. Oxidation system. 14. The hydrothermal oxidation system according to claim 13, further comprising a heating device that heats the liquid to be treated upstream of the electrodialysis device. 15. The hydrothermal oxidation system according to claim 13 or 14, further comprising a removal device for removing solids and suspensions in the liquid to be treated upstream of the electrodialysis device.