JP2003071473A - Method and apparatus for removing pollutant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for removing pollutants which can sufficiently prevent a decrease in the removing capability of pollutants over a long period of time without using an ion-exchange resin. SOLUTION: In the method for removing the pollutant from a water to be treated containing the pollutants including organic halogen compounds, this method comprises a step for supplying an acid to the water to be treated so as to be adjusted to be acidic, a step for supplying hydrogen to the water to be treated, and a step for carrying out a catalytic reaction of the pollutants in the water to be treated with the hydrogen in such a way that the acid and the hydrogen bring the supplied water to be treated into contact with a catalyst. By this method for removing the pollutants, bringing the water to be treated into contact with the catalyst makes the pollutants included in the water to be treated react with the hydrogen, after the acid and hydrogen are supplied to the water to be treated. Then, since the water to be treated is adjusted to be made acidic, precipitation of co-existing materials contained in the water to be treated is inhibited, whereby the co-existing materials is sufficiently prevented from sticking to the catalyst.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pollutant removing method and apparatus for removing pollutants such as organohalogen compounds from polluted soil or sewage, and more particularly to removing organohalogen compounds among pollutants. The present invention relates to a pollutant removal method and device.

[0002]

2. Description of the Related Art Recently, environmental pollution due to harmful organic halogen compounds has become a big social problem. In particular, the spread of contamination by organic halogen compounds such as tetrachloroethylene (PCE), trichlorethylene (TCE), and dichloroethylene (DCE) is becoming clear in electronics-related factories and places where solvents are used for cleaning. It is believed that these organic halogen compounds, which remain in the soil, are dissolved in groundwater by rainwater etc. and spread throughout the surrounding area. Organohalogen compounds are suspected to have carcinogenicity and reproductive toxicity, and are extremely stable in the environment. Therefore, groundwater used as a source of drinking water is a major social problem. There is.
As a method for removing these harmful organic halogen compounds, a method of supplying hydrogen to groundwater or the like in which the organic halogen compound is dissolved and dehalogenating using a catalyst is disclosed in JP-A-6-182361. There is.

[0003]

However, the removal method described in the above-mentioned conventional publication has the following problems. That is, since coexisting substances such as iron dissolved in groundwater adhere to the catalyst and significantly reduce the catalytic activity, it is necessary to remove these coexisting substances with an ion exchange resin in advance. Therefore, there is a problem that it is necessary to newly provide an ion exchange tower, and to perform complicated disposal and regeneration treatment of the ion exchange resin.

The present invention has been made in order to solve the above-mentioned problems, and in particular, a method for removing contaminants capable of sufficiently preventing deterioration of contaminant removal performance for a long time without using an ion exchange resin, and The purpose is to provide a device.

[0005]

In order to solve the above problems, a pollutant removing method according to the present invention is a pollutant removing method for removing pollutants from water to be treated containing pollutants containing organic halogen compounds. , An acid supply step of supplying an acid to the water to be treated to adjust the acidity, a hydrogen supply step of supplying hydrogen to the water to be treated, and a treatment water to which the acid and hydrogen have been supplied are brought into contact with a catalyst, It is characterized by comprising a catalytic reaction step of reacting pollutants in the treated water with hydrogen.

This pollutant removal method is a method of removing organohalogen compounds from wastewater containing pollutants such as organohalogen compounds, heavy metals and oils. According to this pollutant removal method, after supplying acid and hydrogen to the water to be treated containing the pollutants, the water to be treated is brought into contact with the catalyst, whereby the pollutants contained in the water to be treated react with hydrogen. To do. At this time, since the water to be treated is adjusted to be acidic, the precipitation of the coexisting substance contained in the water to be treated is prevented, and the adhesion of the coexisting substance to the catalyst is sufficiently prevented.

The above method preferably further comprises a solid-liquid separation step of adding a coagulant to the water to be treated and performing solid-liquid separation. In this case, by adding a coagulant to the water to be treated,
Contaminants such as heavy metals and oil in the water to be treated are aggregated, and the aggregates are removed from the water to be treated by solid-liquid separation.

The pollutant removal method according to the present invention is a pollutant removal method for removing pollutants from polluted soil containing pollutants containing organic halogen compounds, which comprises a washing step for washing polluted soil and a washing step. A solid-liquid separation step of adding a coagulant to the treated water to perform solid-liquid separation, an acid supply step of supplying an acid to the treated water obtained by the solid-liquid separation step to adjust the acidity, and a solid-liquid separation step A hydrogen supply step of supplying hydrogen to the water to be treated obtained by the above, and a catalytic reaction step of contacting the water to be treated to which acid and hydrogen have been supplied with a catalyst to react pollutants in the water to be treated with hydrogen. It is characterized by being provided.

This pollutant removal method is a method of removing organohalogen compounds from polluted soil containing pollutants such as organohalogen compounds, heavy metals and oils. According to this pollutant removal method, the treated water in which the pollutant is dissolved can be obtained by washing the polluted soil. When a flocculant is added to the water to be treated, contaminants such as heavy metals and oil are flocculated, and the flocculate is removed by solid-liquid separation. Then, after supplying acid and hydrogen to the water to be treated obtained by the solid-liquid separation and then bringing the water to be treated into contact with the catalyst, the pollutants contained in the water to be treated react with hydrogen. At this time, since the water to be treated is adjusted to be acidic, the precipitation of coexisting substances contained in the water to be treated is prevented,
Adhesion of the coexisting substance to the catalyst is sufficiently prevented.

In the hydrogen supply step, it is preferable to supply hydrogen to the water to be treated by electrolyzing the water to be treated. In this case, not only hydrogen is supplied, but harmful metal ions are deposited by electrolysis,
It is possible to reduce or oxidize other harmful substances to render them harmless.

Further, the pollutant removal device according to the present invention is
In a pollutant removal device for removing pollutants from water to be treated containing pollutants containing organic halogen compounds, an acid feeder for supplying an acid to the water to be treated, and a hydrogen supply means for supplying hydrogen to the water to be treated And a catalyst reactor having a catalyst filling portion filled with a catalyst, and the catalyst filling portion being provided with a water to be treated in which acid and hydrogen are supplied.

According to this pollutant removing device, the acid is supplied to the water to be treated by the acid feeder, the water to be treated is adjusted to be acidic, and hydrogen is supplied by the hydrogen supplying means, a part of which is treated water. Dissolve in. Then, the water to be treated supplied with hydrogen and acid is brought into contact with the catalyst in the catalyst-filled portion in the catalytic reactor, and the pollutants in the water to be treated react with hydrogen.
At this time, since the water to be treated is adjusted to be acidic by the acid feeder, the precipitation of the coexisting substance contained in the water to be treated is prevented, and the coexisting substance is sufficiently adhered to the catalyst in the catalyst filling part. Can be prevented.

Further, it is preferable to further comprise a hydrogen dissolving tank for dissolving hydrogen in the water to be treated. In this case, since the residence time of hydrogen becomes long, the efficiency of dissolving hydrogen in the water to be treated is improved.

Further, it is preferable that the hydrogen dissolving tank is an electrolytic tank. In this case, it is possible to remove harmful metal ions and the like.

In the present specification, "removal of contaminants" includes dehalogenation of organic halogen compounds.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the pollutant removal method and apparatus according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a flow sheet schematically showing a pollutant removing device (hereinafter referred to as “removing device”) 10 according to a first embodiment of the present invention. As shown in FIG. 1, the removal device 10 has a storage tank 11 that stores sewage containing an organic halogen compound (hereinafter referred to as “water to be treated”). The water to be treated is, for example, groundwater containing an organic halogen compound, cleaning wastewater generated by cleaning soil contaminated with an organic halogen compound, or the like.

A line L11 is connected to the storage tank 11, and an acid supplier 12 for supplying an acid to the line L11 is connected to the line L11 via a line L0. Acids include, for example, hydrochloric acid, sulfuric acid, nitric acid, sodium acid sulfate, potassium acid sulfate, organic acids (citric acid, tartaric acid, etc.)
An acidic substance such as sulfuric acid is usually used as the acid, which does not require post-treatment. Further, a hydrogen dissolution tank 13 that dissolves hydrogen in the water to be treated to which the acid has been supplied is connected to the storage tank 11 via a line L11. The hydrogen is a hydrogen cylinder (hydrogen supply means) 1 connected to the hydrogen dissolution tank 13.
Supplied from No. 4. The hydrogen dissolution tank 13 is connected to the bottom of the catalytic reactor 15 via a line L12, and inside the catalytic reactor 15, a catalyst packed bed (catalyst packed part) A filled with a catalyst is installed. ing.

The catalyst packed in the catalyst-packed layer A is, for example, an acid-resistant precious metal-based catalyst obtained by impregnating or containing a precious metal such as platinum or palladium on a carrier such as alumina, titania, zirconia, silica or activated carbon. Used. Further, as the shape of the catalyst, various shapes such as spherical shape, cylindrical shape, cylindrical shape, crushed shape, and honeycomb shape can be used. Further, the particle size of the catalyst is usually 1 mm to several tens of mm, preferably several mm to 10 mm, in consideration of blockage of the catalyst packed bed A, water resistance, and contact effect between the catalyst and the water to be treated. Used. When the catalyst has a honeycomb shape, the size of the voids is preferably about 1 mm to 10 mm. The processing rate of the catalytic reactor 15 is 0.5 to 50 h- ¹ , preferably 2 to 20 h- ¹ . Also, the catalytic reactor 1
A line L13 for discharging the water to be treated that has passed through the catalyst-packed layer A is connected to 5. The line L13 may be connected to the bottom of the catalytic reactor 15 and the line L12 may be connected to the upper part of the catalytic reactor 15.

Next, a method for removing contaminants using the removing device 10 having the above-described structure will be described.

First, when the water to be treated is stored in the storage tank 11, the water to be treated is discharged from the storage tank 11 through the line L11. Then, to the water to be treated in the line L11, an acid is supplied from the acid supplier 12 via the line L0, and the water to be treated is adjusted to be acidic (acid supplying step). At this time, the pH of the water to be treated is preferably 1-5, more preferably 2-
Adjust to about 4. Thereby, coexisting substances in the water to be treated (for example, iron, manganese, calcium, magnesium,
Aluminum, silicon, etc.) is prevented. Thus, the water to be treated to which the acid has been supplied is introduced into the hydrogen dissolving tank 13 via the line L11.

In the hydrogen dissolution tank 13, hydrogen is supplied to the water to be treated from the hydrogen cylinder 14, and a part of the supplied hydrogen is dissolved in the water to be treated (hydrogen supplying step). In addition, it is preferable to supply hydrogen in the form of fine bubbles with a diffuser or the like in order to further promote the dissolution. After that, the water to be treated is introduced into the bottom of the catalytic reactor 15 through the line L12 and passes through the catalyst packed bed A provided inside the catalytic reactor 15. When the water to be treated passes through the catalyst packed bed A, the water to be treated comes into contact with the catalyst, and the organohalogen compound in the water to be treated reacts with hydrogen in the water to be treated and is dehalogenated by the catalytic action. At this time, since the water to be treated is adjusted to be acidic, in the water to be treated, the precipitation of the coexisting substance is prevented as described above, and the adhesion of the coexisting substance to the catalyst is sufficiently prevented for a long time. Therefore, it is possible to maintain the catalyst performance for a long time without using an ion exchange resin, and it is possible to sufficiently prevent the deterioration of the organic halogen compound removal performance.

The water to be treated which has been rendered harmless by dehalogenation in this way is fed from the upper part of the catalytic reactor 15 to the line L.
It is released after 13 years. At this time, the neutralizing agent (alkali agent) is supplied to the water to be treated flowing through the line L13, and the neutralizing treatment is performed.

By connecting the line L11 to the bottom of the catalytic reactor 15 instead of the hydrogen dissolving tank 13, and connecting the hydrogen cylinder 14 to the bottom of the catalytic reactor 15,
The hydrogen dissolution tank 13 and the line L12 can be omitted. Also,
In order to accelerate the dissolution of hydrogen in the hydrogen dissolution tank 13,
Hydrogen may be dissolved in the water to be treated under pressure. further,
In order to prevent the catalyst packed bed A of the catalytic reactor 15 from being clogged with solids or bubbles, air or water for backwashing may be injected into the bottom. When the water to be treated is discharged, the water to be treated may be further subjected to post-treatments such as solid-liquid separation (separation separation, flotation separation, filtration separation, membrane separation, etc.) and adsorption separation. Further, the hydrogen dissolution tank 13 may be omitted. Even in this case, it is possible to supply hydrogen using the hydrogen cylinder 14.

Next, a second embodiment of the present invention will be described. FIG. 2 shows a removing device 2 according to the second embodiment of the present invention.
It is a flow sheet which shows 0 roughly. In addition, the same or equivalent components as those of the first embodiment are designated by the same reference numerals,
A duplicate description will be omitted.

The removing device 20 has a cleaning tank 21 for cleaning the contaminated soil. In the cleaning tank 21, water and, if necessary, an acid (inorganic acid, organic acid), an oxidizing agent, a reducing agent, a chelating agent, a surfactant, or the like is used to wash the contaminated soil, so that heavy metals, oil, etc. Are separated from contaminated soil. A line L21 is connected to the cleaning tank 21, and cleaning wastewater (water to be treated) in the cleaning tank 21 is introduced into the storage tank 11 via the line L21. The storage tank 11 is connected to the solid-liquid separation tank 22 via a line L22, and the cleaning wastewater stored in the storage tank 11 is introduced into the solid-liquid separation tank 22 via the line L22. A coagulant, a neutralizing agent, and the like are added to the line L22, if necessary. Therefore, the addition of the coagulant causes the pollutants such as heavy metals and oil in the cleaning waste water to coagulate and be separated in the solid-liquid separation tank 22.

The solid-liquid separation tank 22 is connected to the hydrogen dissolution tank 13 via a line L23, and the acid is supplied to the line L23 from the acid supply device 12 described above. Similar to the first embodiment, the hydrogen tank 14 is connected to the hydrogen dissolving tank 13, and the hydrogen dissolving tank 13 is connected to the catalytic reactor 15 via the line L24. Catalytic reactor 15
The cleaning wastewater that has passed through the catalyst-packed bed A in 1 is discharged through the line L25. A line L26 for returning the cleaning wastewater to the cleaning tank 21 is connected in the middle of the line L25.

Next, a method for removing contaminants contained in the contaminated soil using the removing device 20 will be described.

First, the contaminated soil and cleaning water are put into the cleaning tank 21. In addition to washing water, acids (inorganic acids, organic acids), oxidizing agents, reducing agents, chelating agents,
A surfactant or the like is put into the cleaning tank 21. As a result, pollutants such as heavy metals, oils, and organic halogen compounds can be separated from the contaminated soil, and the contaminated soil is washed (washing step). The soil from which the contaminants have been removed is taken out from the bottom of the cleaning tank 21 and reused as treated soil. On the other hand, the cleaning wastewater containing pollutants flows out from the cleaning tank 21 through the line L21 and is introduced into the storage tank 11.

The cleaning wastewater stored in the storage tank 11 is supplied to the solid-liquid separation tank 22 via a line L22. At this time, a coagulant (for example, an inorganic coagulant such as an iron-based, aluminum-based, silica-based, or calcium-based) is added to the cleaning wastewater in the line L22. If necessary, sulfide (N
a ₂ S, etc.), a neutralizing agent, a polymer flocculant, etc. may be added. The washing wastewater to which such a flocculant is added flows into the solid-liquid separation tank 22. In the solid-liquid separation tank 22, contaminants such as heavy metals and oil are aggregated and removed from the washing wastewater, and thus solid-liquid separation is performed (solid-liquid separation step). afterwards,
The cleaning wastewater of the solid-liquid separation tank 22 is introduced into the hydrogen dissolving tank 13 via the line L23, and the cleaning waste liquid flowing in the line L23 is supplied with acid from the acid supplier 12 (acid supply step).

Hydrogen is supplied to the hydrogen dissolving tank 13 from the hydrogen cylinder 14, and a part of the hydrogen is dissolved in the cleaning wastewater (hydrogen supplying step). The cleaning wastewater in which hydrogen is dissolved is line L
It is introduced into the catalytic reactor 15 via 24. In the catalytic reactor 15, the cleaning wastewater in which hydrogen is dissolved passes through the catalyst packed bed A (catalytic reaction step). At this time, since the cleaning wastewater is adjusted to be acidic, the coexisting substances are prevented from being deposited as described above, and the coexisting substances are sufficiently prevented from adhering to the catalyst for a long time. Therefore, it is possible to maintain the catalyst performance for a long time without using an ion exchange resin, and it is possible to sufficiently prevent the deterioration of the organic halogen compound removal performance. The detoxified cleaning wastewater is discharged via the line L25, and a part of the cleaning wastewater is returned to the cleaning tank 21 via the line L26 branched from the middle of the line L25. As a result, the cleaning wastewater can be efficiently reused as the cleaning water for the contaminated soil.

As described above, according to the removing device 20, the coagulant is added to the washing wastewater generated when the contaminated soil is washed to perform solid-liquid separation, thereby removing the pollutants such as heavy metals and oil. The organic halogen compound can be removed by supplying an acid to the washing wastewater obtained by solid-liquid separation. Therefore, it is possible to effectively treat contaminated soil that is complex contaminated with heavy metals, oils, etc. in addition to the organic halogen compound.

In the removing device 20 of this embodiment, the storage tank 11 may be omitted. In this case, the line L21 is connected to the solid-liquid separation tank 22, and the line L21 is
At 21, the coagulant will be added to the wash wastewater.

Next, regarding the third embodiment of the present invention,
This will be described with reference to FIG. It should be noted that the same or equivalent constituent elements as those of the first embodiment are designated by the same reference numerals, and overlapping description will be omitted. FIG. 3 is a flow sheet schematically showing a removing device 30 according to the third embodiment of the present invention.

As shown in FIG. 3, the removing device 30 differs from the removing device 10 of the first embodiment in that a solid-liquid separation tank 22 is installed between the storage tank 11 and the hydrogen dissolving tank 13. The acid supplier 12 is connected to a line L32 that connects the solid-liquid separation tank 22 and the hydrogen dissolution tank 13 via a line L0. Further, in the removing device 30, the storage tank 1
The above-mentioned coagulant is added in a line L31 that connects 1 and the solid-liquid separation tank 22. Therefore, contaminants such as heavy metals and oil can be removed in the solid-liquid separation tank 22. Therefore, not only the organic halogen compound but also the cleaning wastewater from which pollutants such as heavy metals and oil have been removed can be discharged from the catalytic reactor 15.

Next, regarding the fourth embodiment of the present invention,
This will be described with reference to FIG. It should be noted that the same or equivalent constituent elements as those of the first embodiment are designated by the same reference numerals, and overlapping description will be omitted. FIG. 4 is a flow sheet schematically showing a removing device 40 according to the fourth embodiment of the present invention.

As shown in FIG. 4, in the removing device 40, the storage tank 11 is connected to the electrolytic cell 42 via a line L11, and inside the electrolytic cell 42, an anode 43 and a cathode 44 are arranged. ing. The anode 43 and the cathode 44 have a flat plate shape and are installed in parallel with each other. For the anode 43 and the cathode 44, for example, carbon, platinum, silver, iron, copper, nickel, titanium, stainless steel, or various metals coated with a platinum group metal is used. Anode 43 and cathode 4
The distance between 4 is usually set to a distance between electrodes of several cm to several tens of cm so that the electric resistance does not become too high.
The anode 43 and the cathode 44 are connected to a power source (not shown), and the power source, the anode 43 and the cathode 44 constitute a hydrogen supply means.

An acid supplier 12 for supplying an acid to the line L11 is connected to the line L11 via a line L0, and an electrolyte supplier 41 for supplying an electrolyte to the line L11 is connected via a line L1. It is connected. The electrolyte supplied from the electrolyte supplier 41 is, for example, a sulfate such as potassium or sodium, a chloride, a nitrate, an organic acid salt, or the like. Further, the electrolytic cell 42 is connected to the catalytic reactor 15 via a line L12, and the catalytic reactor 15 is discharged with a line L13 for discharging the water to be treated which has passed through the catalyst packed bed A.
Are connected.

Next, a method of removing contaminants using the removing device 40 will be described.

First, the water to be treated stored in the storage tank 11 flows into the electrolytic tank 42 through the line L11. At this time, the water to be treated in the line L11 is supplied with an acid from the acid feeder 12 through the line L0 to adjust the water to be treated to be acidic (acid supplying step) and, if necessary, to supply an electrolyte. The electrolyte is supplied from the container 41 through the line L1. In the electrolytic cell 42, an anode 43 and a cathode 44 are supplied by a power source.
The voltage is applied between. The applied voltage is usually several volts to several tens of volts. The current density is determined by the required amount of hydrogen, etc., but is usually several A / m ² to several thousand A /
It is about m ² . Therefore, the water in the water to be treated that has flowed into the electrolytic bath 42 is electrolyzed, whereby hydrogen is generated and a part of the hydrogen is dissolved in the water to be treated (hydrogen supply step).

At this time, the water to be treated is adjusted to be acidic in the electrolytic bath 42. Specifically, the pH is 1 to
It is adjusted to 5, preferably 2 to 4. By adjusting the pH to this range, the anode 43 and the cathode 4 of the electrolytic cell 42
4 (particularly the cathode 44) can be prevented from adhering a carbonate (calcium salt, magnesium salt, etc.) to the electrode 4 and the resulting reduction in electrolytic effect, and stable electrolysis is possible. That is, hydrogen can be stably supplied by electrolysis. In addition, in the electrolytic bath 42, not only hydrogen is supplied to the water to be treated, but also harmful metal ions in the water to be treated are deposited by electrolysis, and other harmful substances are reduced or oxidized to render them harmless. It becomes possible.

The water to be treated in which hydrogen has been dissolved in the electrolytic cell 42 is supplied to the catalytic reactor 15 through line L12,
It passes through the catalyst packed bed A. When the water to be treated passes through the catalyst-packed layer A, the organohalogen compound is dehalogenated by reacting with hydrogen by a catalytic action to be rendered harmless (catalytic reaction step). At this time, since the water to be treated is adjusted to be acidic, the precipitation of the coexisting substance is prevented and the adhesion of the coexisting substance of the catalyst is sufficiently prevented. Therefore, it is possible to maintain the catalyst performance for a long time without using an ion exchange resin, and it is possible to sufficiently prevent the deterioration of the organic halogen compound removal performance. The water to be treated discharged from the catalytic reactor 15 is neutralized with an alkaline agent, or after further post-treatment such as solid-liquid separation and adsorption separation, the line L13.
It is then released or reused.

In the present embodiment, the acid or electrolyte may be added directly to the electrolytic cell 42. Further, a cylindrical electrode can be used instead of the plate-shaped electrode. In this case, a plurality of cylindrical electrodes having different diameters are arranged concentrically. In addition, various shapes such as a mesh shape, a grid shape, and a pipe can be used as the shape of the electrode. Furthermore, the anode 4
In order to prevent the contamination of the cathode 3 and the cathode 44, the polarities of the anode 43 and the cathode 44 may be appropriately exchanged for operation.

Next, a fifth embodiment of the present invention will be described. FIG. 5 shows a removing device 5 according to the fifth embodiment of the present invention.
It is a flow sheet which shows 0 roughly.

As shown in FIG. 5, a catalyst packed bed A is disposed inside the catalytic reactor 15, and a hydrogen dissolution chamber 51 is provided below the catalyst packed bed A. Hydrogen dissolution chamber 51
An anode 43 and a cathode 44 are arranged in the anode, and the anode 43 and the cathode 44 are electrically connected to a power source (not shown). Then, the water to be treated stored in the storage tank 11 is introduced into the hydrogen dissolution chamber 51 of the catalytic reactor 15 through the line L51. Therefore, when power is supplied from the power source, the water to be treated is electrolyzed in the hydrogen dissolving chamber 51 to generate hydrogen, and a part of the water is dissolved in the water to be treated. The anode 43, the cathode 44, and the power supply constitute hydrogen supply means. Further, the water to be treated in the line L51 is supplied with an acid from the acid supplier 12 via the line L0 and, if necessary, an electrolyte from the electrolyte supplier 41 via the line L1. Further, in the catalytic reactor 15, a line L52 for discharging the water to be treated which has passed through the catalyst packed bed A.
Are connected.

Also in the removing apparatus 50 having the above-described structure, when the water to be treated passes through the catalyst packed bed A, the organic halogen compound in the water to be treated reacts with hydrogen in the water to be treated by a catalytic action. It is dehalogenated. At this time, since the water to be treated is adjusted to be acidic, the precipitation of the coexisting substance is prevented, and the adhesion of the coexisting substance to the catalyst is sufficiently prevented for a long time. Therefore, it is possible to maintain the catalyst performance for a long time without using an ion exchange resin, and it is possible to sufficiently prevent the deterioration of the organic halogen compound removal performance. Further, according to the removing device 50 of the present embodiment, since the anode 43 and the cathode 44 for electrolysis are arranged inside the catalytic reactor 15, the electrolytic cell 42 used in the removing device 40 of the fourth embodiment is It becomes unnecessary. Thereby, the removing device 50 can be made smaller than the removing device 40 of the fourth embodiment. Further, due to the downsizing of the removing device, undissolved hydrogen passes through the catalytic reactor in the form of fine bubbles, so that clogging of the catalyst packed bed due to bubbles can be suppressed. Instead of supplying hydrogen using the anode 43 and the cathode 44, hydrogen may be supplied by the hydrogen cylinder 14 or the like.

The present invention is not limited to the above embodiment. For example, in the removing apparatus of the second and third embodiments, the hydrogen dissolving tank 13 may be replaced by the electrolytic tank 42, and the hydrogen cylinder 14 may be replaced by the anode 43 and the cathode 44. Further, in the first to third embodiments described above, hydrogen is supplied to the water to be treated that has been adjusted to be acidic, but the water to be treated after supplying hydrogen may be adjusted to be acidic.

The contents of the present invention will be specifically described below with reference to examples.

[0049]

Example 1 Using the pollutant removing device 10 as shown in FIG. 1, the water to be treated was treated as follows. That is, first, 3 liters / hour of ground water (water to be treated) containing trichlorethylene 2 mg / l at about 20 ° C. was taken out from the storage tank 11, and sulfuric acid was added to this by an acid feeder 12 to adjust the pH to 3, It was introduced into a 0.5 liter hydrogen dissolution tank 13. At this time, hydrogen was supplied from the bottom of the hydrogen dissolving tank 13 at a rate of about 10 ml per minute by the hydrogen cylinder 14 to dissolve the hydrogen. In this way, the water to be treated in which hydrogen was dissolved was treated at a treatment rate of 10 in a catalyst packed bed A of a catalyst reactor 15 in which 300 ml of a platinum-supported titania catalyst (platinum supported amount: 0.35 wt%, particle size: about 2 mmφ) was packed.
After passing through h- ¹ , continuous operation was carried out for 500 hours. At this time, the trichloroethylene concentration (A) in the storage tank 11 and the trichlorethylene concentration (B) in the line L13 were measured at the start of operation and after 500 hours of operation, respectively, and the following formula was used: Removal rate (%) = (AB ) × 100 / A 2, the removal rate was calculated. As a result, the removal rate of trichlorethylene was 98% and 5% at the beginning of operation.
It was 96% even after 00 hours, and the high removal rate was maintained for a long time.

(Comparative Example 1) In the same manner as in Example 1 except that sulfuric acid was not added, the removal apparatus 10 was continuously operated to treat the water to be treated. Then, in the same manner as in Example 1, the removal rate of trichlorethylene was calculated at the start of operation and after 500 hours of operation. as a result,
The removal rate of trichlorethylene was 98 at the beginning of operation.
%, But it decreased to 60% after 500 hours, and it was found that the removal performance of trichlorethylene as a pollutant decreased with time. It is considered that this is because calcium, magnesium, manganese, etc. adhered to or adsorbed on the catalyst in the catalyst-packed layer A, resulting in a marked decrease in catalyst performance.

(Example 2) Using the pollutant removing device 40 as shown in FIG. 4, the water to be treated was treated as follows. That is, first, 3 liters / hour of ground water (water to be treated) containing trichlorethylene (2 mg / l) at about 20 ° C. is taken out from the storage tank 11, and sulfuric acid is added thereto to adjust the pH to 3
After adjusting to 0.5 liter of electrolytic cell (5 × 5 × 20
cm height) 42. In the electrolysis tank 42, a platinum-plated titanium plate anode (5 × 4 × 0.5 cm thickness) 43 and a stainless steel plate cathode (5 × 4 × 0.5 cm thickness) 44 were placed one by one at a distance of 3 cm. Two pieces were arranged and electrolysis was performed with an electrolytic current of about 3A. In this way, the water to be treated in which hydrogen was dissolved in the electrolytic cell 42 was converted to 30 by the platinum-supporting titania catalyst (platinum-carrying amount 0.35 wt%, particle size about 2 mmφ).
The removal device 40 was continuously operated for 500 hours by passing it through the catalyst packed bed A of the catalyst reactor 15 filled with 0 ml at a processing rate of 10 h- ¹ . Then, the removal rate of trichlorethylene was calculated in the same manner as in Example 1 at the start of operation and after 500 hours of operation. As a result, the removal rate of trichlorethylene was 98% at the beginning of operation and 96% after 500 hours, and the high removal rate was maintained for a long time.

Comparative Example 2 The water to be treated was treated by continuously operating the removing device 40 in the same manner as in Example 2 except that sulfuric acid was not added. And at the start of operation and 50
After each operation for 0 hours, the removal rate of trichlorethylene was calculated in the same manner as in Example 1. as a result,
The removal rate of trichlorethylene was 98 at the beginning of operation.
%, But it decreased to 45% after 500 hours, and it was found that the removal performance of trichlorethylene as a contaminant decreases with time. This is the electrolyzer 4
2, the anode 43 and the cathode 44 are contaminated, resulting in defective generation of hydrogen, and the catalyst packed bed A
It is considered that this is because calcium, iron, manganese, etc. adhered to or adsorbed on the catalyst of (1) and the catalytic performance was significantly lowered.

(Embodiment 3) In the pollutant removing device 20 as shown in FIG. 2, instead of the hydrogen dissolving tank 13, the electrolytic tank 4 is used.
2 (see FIG. 4) was used to treat contaminated soil as follows. As contaminated soil, lead elution amount is 0.21m
g / l, total mercury elution amount was 0.010 mg / l, and tetrachloroethylene elution amount was 0.18 mg / l. 100 kg of this contaminated soil and 1000 liters of water are put into the washing tank 21, and sulfuric acid is added to this to adjust the pH to about 5
The mixture was adjusted to, stirred for about 30 minutes, and then allowed to stand. Then, the cleaning wastewater of the supernatant water was stored in the storage tank 11. In the washing tank 21, 1000 liters of water was again added to the precipitated soil, the mixture was stirred for 30 minutes, and then allowed to stand still, and the washing waste water of the supernatant water was stored in the storage tank 11. The cleaning wastewater thus collected in the storage tank 11 is about 1900 liters, and the concentration of tetrachlorethylene in the cleaning wastewater is 0.1.
It was 75 mg / l.

On the other hand, the analysis results of the elution amount of the washed soil showed that the elution amount of lead was 0.006 mg / l, the elution amount of total mercury was 0.0003 mg / l, and the elution amount of tetrachloroethylene was 0.005 mg / l. In all cases, the soil environmental standards were satisfied. Then, the cleaning wastewater stored in the storage tank 11 is taken out at 3 liters per minute, and an inorganic coagulant (aluminum sulfate), a neutralizing agent (sodium hydroxide) and a polymer coagulant are added thereto to adjust the pH of the water to be treated. Was about 7 and the aggregation treatment was performed. Then, solid-liquid separation was performed in the solid-liquid separation tank 22 to remove solids in the cleaning wastewater. The concentration of lead in the cleaning wastewater discharged from the solid-liquid separation tank 22 is 0.01 mg / l or less, and the concentration of total mercury is 0.0
It was 005 mg / l or less, and most of pollutants such as lead and mercury were removed. At this point, the concentration of tetrachlorethylene was 0.14 mg / l, and tetrachloroethylene was removed only about 20%. Sulfuric acid is added to the cleaning wastewater discharged from the solid-liquid separation tank 22 from the acid supplier 12 to adjust the pH to 3, and the cleaning wastewater is sequentially passed through the electrolytic tank 42 and the catalytic reactor 15 to remove the removing device 20. Was continuously operated. At this time, at the start of operation and after 500 hours of operation, the line L
The tetrachloroethylene concentration (C) in 23 and the tetrachloroethylene concentration (D) in line L25 were measured, and the removal rate was calculated based on the following formula: removal rate (%) = (C−D) × 100 / C. As a result, the removal rate of tetrachlorethylene was 97% and 50% at the beginning of operation.
It was 95% even after 0 hour, and a high removal rate was obtained for a long time.

(Comparative Example 3) The contaminated soil was treated in the same manner as in Example 3 except that sulfuric acid was not added. And
At the start of operation and after 500 hours of operation,
The removal rate of tetrachloroethylene was calculated in the same manner as in Example 3. As a result, it was found that the removal rate of tetrachlorethylene was 97% at the beginning of the operation, but it decreased to 40% after 500 hours, and the removal performance of tetrachlorethylene as a pollutant decreased with time. This is because in the electrolytic cell 42, the anode 43 and the cathode 44 are contaminated, resulting in defective generation of hydrogen. In the catalytic reactor 15, calcium, magnesium, iron, manganese, or the like adheres to the catalyst of the catalyst packed bed A or It is considered that this is because the catalyst performance was remarkably lowered due to adsorption.

In the above Examples and Comparative Examples,
Analysis of the elution amount and concentration of lead, total mercury, trichlorethylene, and tetrachloroethylene is conducted by the Environmental Agency Notification No. 46 (19
1991; soil environmental standards).

[0057]

As described above, according to the pollutant removal method and apparatus of the present invention, when the pollutant and hydrogen are reacted with each other by the catalytic action, the water to be treated is adjusted to be acidic. It is possible to prevent the coexisting substance from being deposited and to sufficiently prevent the coexisting substance from adhering to the catalyst. Therefore, it is possible to sufficiently prevent the deterioration of the contaminant removal performance over a long period of time without removing the coexisting substances with the ion exchange resin in advance.

[Brief description of drawings]

FIG. 1 is a flow sheet showing a contaminant removing device according to a first embodiment of the present invention.

FIG. 2 is a flow sheet showing a pollutant removal device according to a second embodiment of the present invention.

FIG. 3 is a flow sheet showing a contaminant removing device according to a third embodiment of the present invention.

FIG. 4 is a flow sheet showing a pollutant removal device according to a fourth embodiment of the present invention.

FIG. 5 is a flow sheet showing a contaminant removing device according to a fifth embodiment of the present invention.

[Explanation of symbols]

10, 20, 30, 40, 50 ... Pollutant removal device, 1
1 ... Storage tank, 12 ... Acid feeder, 13 ... Hydrogen dissolution tank, 14
... hydrogen cylinder (hydrogen supply means), 15, 51 ... catalytic reactor, 22 ... solid-liquid separation tank, 42 ... electrolysis tank, 43 ... anode (hydrogen supply means), 44 ... cathode (hydrogen supply means), 51 ... hydrogen Melting chamber, A ... Catalyst packed bed (catalyst packed part).

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C02F 9/00 502 C02F 9/00 502Z 503C B09B 5/00 ZABS 503 C02F 1/46 101C (72) Inventor Shinichi Yamada 1-15 Kyoritsutsumi, Hiratsuka-shi, Kanagawa Sumitomo Heavy Industries Machinery Co., Ltd. Hiratsuka Office F-term (reference) 4D004 AA41 AB03 AB06 CA13 CA37 CA40 CB05 4D038 AA08 AB14 AB63 BA04 BB13 BB15 BB18 4D050 AA12 AB19 AB52 BA14 BC04 BD02 BD03 BD04 BD06 CA13 CA16 4D061 DA08 DB19 DC09 EA02 EB04 ED12 FA11 FA14 FA17

Claims (7)

[Claims] 1. A pollutant removal method for removing the pollutant from water to be treated containing a pollutant containing an organic halogen compound, the step of supplying an acid to the water to be treated to adjust the acidity, A hydrogen supply step of supplying hydrogen to the water to be treated, and a catalytic reaction step of contacting the water to be treated to which the acid and the hydrogen have been supplied with a catalyst to react contaminants in the water to be treated with hydrogen A method for removing pollutants, comprising: 2. The pollutant removal method according to claim 1, further comprising a solid-liquid separation step of adding a coagulant to the water to be treated and performing solid-liquid separation. 3. A pollutant removal method for removing the pollutant from a polluted soil containing a pollutant containing an organohalogen compound, comprising: a washing step for washing the polluted soil; and a treated water obtained by the washing step. A solid-liquid separation step of adding a flocculant to perform solid-liquid separation, an acid supply step of supplying an acid to the water to be treated obtained by the solid-liquid separation step to adjust the acidity, and a solid-liquid separation step A hydrogen supply step of supplying hydrogen to the treated water to be treated, and a catalytic reaction step of contacting the treated water to which the acid and the hydrogen have been supplied with a catalyst to react pollutants in the treated water with hydrogen. A method for removing pollutants, comprising: 4. The pollutant according to claim 1, wherein in the hydrogen supplying step, hydrogen is supplied to the water to be treated by electrolyzing the water to be treated. Removal method. 5. A pollutant removal apparatus for removing the pollutant from the water to be treated containing the pollutant containing an organic halogen compound, comprising: an acid supplier for supplying an acid to the water to be treated; A hydrogen supply means for supplying hydrogen, and a catalyst reactor having a catalyst filling part filled with a catalyst, and flowing the treated water supplied with acid and hydrogen into the catalyst filling part. The pollutant removal device. 6. The pollutant removal device according to claim 5, further comprising a hydrogen dissolving tank for dissolving hydrogen in the water to be treated. 7. The pollutant removal device according to claim 6, wherein the hydrogen dissolution bath is an electrolysis bath.