JP2001300521A - Harmful material treating method and harmful material treating device used for the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decompose and clean a harmful material contained in soil and underground water in a solution at an ordinary temperature while preventing the use of a chemical agent and the generation of secondary pollution. SOLUTION: In the harmful material treating method including the first stage in which a harmful material 4 in liquid is adsorbed by an adsorbent 5 incorporated in an absorption tower 6, the second stage in which the harmful material 4 is desorbed from the adsorbent 5 and the third stage in which the harmful material-containing liquid 17 obtained at the second stage is cleaned, and in the third stage, the absorption tower effluent 17 is stored at a water storage tank 9, and the liquid 10 is subjected to cavitation jet 15 by a nozzle 13, and the treated liquid 16 cleaned by the cavitation is sent to the second stage, and in second stage, the harmful material 4 is desorbed from the adsorbent 5 by using the treated liquid 16 to regenerate the adsorbent 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for purifying harmful organic compounds (hazardous substances) present in a very small amount in a fluid, and more particularly, to a method for efficiently removing harmful organic compounds in contaminated soil, groundwater or wastewater. The present invention relates to a method for treating harmful substances that can be made harmless and a toxic substance treatment apparatus used in the method.

[0002]

2. Description of the Related Art The soil and water environment surrounding the current living environment are contaminated with organic chlorine compounds and the like. A representative example thereof is dioxin discharged from incineration equipment for garbage and industrial waste ( DXN). In factories handling semiconductor electronic components and jet engines, many districts have soil and groundwater pollution problems due to trichlorethylene, which has been used for degreasing and cleaning, and tetrachloroethane (perchrene), which has been frequently used for dry cleaning.

[0003] Organochlorine compounds represented by trichlorethylene are set up as effluent standards because of their carcinogenic properties. It can be said that soil and groundwater contamination was caused by infiltration and the like.
Trichlorethylene contained in soil or groundwater can be diffused into the atmosphere by suction or aeration,
A general treatment method is a method in which the substance is transferred into the gas phase and then adsorbed on an adsorbent such as activated carbon.

[0004] The former merely diffuses harmful substances present in soil or groundwater into the atmosphere, and is not an essential solution. The harmful substance adsorption treatment with activated carbon or the like is performed on gas and liquid, and the harmful substance adsorbed on activated carbon is usually desorbed by heating the activated carbon. If this waste gas is released into the atmosphere, there is no point in adsorbing it on activated carbon, and if a chlorine-containing compound is incinerated, there is a fear that dioxins may be generated.

[0005] In addition, pollution of water bodies by endocrine disrupting substances (so-called "environmental hormones") has been urgently tackled as a new environmental problem. In rivers in large urban areas, problems such as detection of nonylphenol at high concentrations have been revealed, and the problem may be more serious than DXN. The presence of endocrine disruptors has also attracted attention in leachate at the final landfill site for waste, but the decisive effective technology that can detoxify harmful substances that have been diffused at low concentrations in the environment is currently unknown. not exist.

[0006]

Generally, harmful substances such as trichlorethylene contained in soil are subjected to a final detoxification treatment after they are once desorbed (stripped) into the gas phase. . In this case, since trichlorethylene is generated as a very dilute gas, a representative method as a first step of the detoxification treatment of the gas containing trichlorethylene is collection with an adsorbent such as activated carbon. However, a treatment method in which trichlorethylene is desorbed from activated carbon that has collected trichlorethylene and then burned,
There is a danger of generating not only hydrogen chloride gas but also dioxins and the like, which is not an environmentally preferable method.

On the other hand, the method of detoxifying in an aqueous solution (wet method) can avoid the above-mentioned problems, but requires eluting trichloroethylenes from activated carbon and using a special oxidizing agent. WJ (water jet)
The sonochemical decomposition means using is simple in operation, but even with this treatment method, activated carbon adsorbing trichloroethylenes cannot be directly rendered harmless by the WJ / sonochem method. That is, in the case of detoxification treatment by the WJ / Sonochemi method, since the presence of solid particles causes clogging and abrasion of the nozzle, the solution must be a solution in which solids having a predetermined particle size or more are separated.
WJ processing is not possible. In addition, continuous treatment cannot be performed unless trichlorethylenes corresponding to the amount brought into the active monolayer migrate into the liquid.

An object of the present invention is to collect harmful substances such as trichlorethylene contained in soil or groundwater by the activated carbon collection-sonochem method without using any chemicals and generating secondary pollution. It is an object of the present invention to provide a method for treating harmful substances that can be decomposed and purified in an aqueous solution at normal temperature without performing the treatment, and a harmful substance treatment apparatus used in the treatment method.

[0009]

Means for Solving the Problems To achieve the above object, a method for treating harmful substances according to the present invention comprises a first step of adsorbing harmful substances in a fluid to an adsorbent; A harmful substance treatment method including a second step of desorbing and a third step of purifying the harmful substance-containing liquid obtained in the second step, wherein the third step comprises removing the harmful substance-containing liquid. Purification is performed by cavitation, and the treatment liquid is sent to the second step. The second step is configured to desorb harmful substances from the adsorbent using the treatment liquid.

The cavitation in the third step is as follows:
The processing liquid may be generated by a water jet or ultrasonic method, and the treatment liquid may be heated to a temperature not exceeding 60 ° C.

Further, the second step may include a step of supplying clean and cold water at a room temperature or lower to the adsorbent having adsorbed the harmful substance, and desorbing the harmful substance from the adsorbent with the treatment liquid.

Further, harmful substances are aromatic compounds, which are hydroxyl groups (-OH), carboxyl groups (-COOH), alkyl groups (-R), ester groups (-COO) with respect to the benzene nucleus.
R), aldehyde group (-COH), ketone group (-COR), an ether group (-OR), halogen (-F, -Cl, -Br, -I ), amino group (-NH _2), a nitro group ( -NO ₂ ) or a compound having at least one substituent consisting of a sulfonic acid group (-SO ₃ H); dichloromethane, carbon tetrachloride, 1,2-dichloroethane, 1,1-dichloroethylene, cis-1,2 -Halogenated compounds consisting of dichloroethylene, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene or 1,3-dichloropropene, PCBs or halogen compounds consisting of dioxins and CS consisting of thiuram
A configuration including a bond-containing compound may be employed.

The harmful substance treatment apparatus is used in any one of the harmful substance treatment methods described above, and incorporates an adsorbent for harmful substances, discharges the harmful substance-containing liquid, and purifies the harmful substance-containing liquid. An adsorption tower that desorbs harmful substances from the adsorbent with the liquid, and a reactor that inserts a nozzle, purifies by cavitating the harmful substance-containing liquid with the nozzle, and sends out the treated liquid to the adsorption tower,
A configuration including a plurality of adsorption towers may be employed.

As described above, a fluid composed of a gas or liquid containing a harmful substance to be treated is guided to a packed bed of an adsorbent such as activated carbon, and the contained harmful substance is collected.
This trapping process can be carried out under dry conditions for gases and under wet conditions for liquids.If the absorption capacity decreases, the harmful substances in the activated carbon are eluted into the liquid, and the harmful substances are contained. The liquid is purified by the WJ / Sonochem method. WJ /
Detoxification of harmful substances by the sonochem method is achieved by blowing a harmful substance-containing liquid into a liquid as a high-speed jet from a nozzle.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, a first step in which harmful substances (trichloroethylene-containing gas) 4 in a fluid are adsorbed by an adsorbent 5 built in an adsorption tower 6,
A second step of desorbing the harmful substance 4 from the step 5, and a second step of purifying the harmful substance-containing liquid (adsorption tower effluent) 17 obtained in the second step.
The third step is a method of treating a harmful substance comprising the steps of:
0 is jetted from the nozzle 13 at a high-speed jet (cavitation jet) 15 to purify by cavitation and send the processing liquid 16 to the second step. In the second step, the cleaning liquid 16 is harmful to the adsorbent 5 using the cleaning liquid 16 In this configuration, the adsorbent 5 is regenerated by desorbing the substance 4.

The cavitation in the third step is as follows:
The processing liquid 16 generated by a water jet (WJ) or ultrasonic method may be heated to a temperature not exceeding 60 ° C. The second step is to clean the adsorbent 5 which has absorbed the harmful substance 14 Alternatively, a configuration may be employed in which cold water 19 at room temperature or lower is supplied, and the harmful substance 4 is desorbed from the adsorbent 5 by the treatment liquid 16.

That is, FIG. 1 shows an overall system for detoxifying trichlorethylene using cavitation generated by WJ in a purification system for soil contaminated with trichlorethylene.
Vacuum pump 3 sucks trichloroethylene-containing gas (hazardous substance) 4 from soil gas suction well 2 provided at purification target point 1 contaminated with harmful organic compounds and fills with adsorbent 5 represented by activated carbon The adsorbent 5 guides the adsorbent 5 to adsorb and separate trichloroethylenes, and discharges the purified gas from the purified gas discharge line 7 into the atmosphere. In the case of contaminated groundwater or general waste liquid, lead it directly to the adsorption tower 6, or if necessary, blow air into the contaminated liquid while heating to volatilize the trichloroethylenes, and then lead it to the adsorption tower 6. Processing methods can be employed.

Although the present invention is not limited by the type of the adsorption tower or the operating conditions, the operation is intermittently performed by a system (hazardous substance processing apparatus) as shown in FIG. The scheme is the most efficient. That is, granular activated carbon is used as the adsorbent 5, and when the granular activated carbon adsorbs a predetermined amount of trichlorethylenes, the operation of the vacuum pump 3 is stopped, and
Start driving. The liquid (hazardous substance-containing solution) 10 stored in the water storage tank 9 is supplied to a high-pressure pump 8 to increase the pressure to a predetermined pressure (for example, 400 kgf / cm ² ).
Nozzle 1 attached to the upstream end of tubular WJ reactor 12 through 1
From 3, it is blown into the inside of the tubular WJ reactor 12.

At the inlet of the tubular WJ reactor 12, a nozzle 13 for blowing out high-pressure water is inserted via a nozzle mount 14, and a high-pressure hose 11 is connected to the nozzle mount 14. . When the liquid 10 containing harmful substances is blown out from the nozzle 13 as a high-speed jet, the inside of the tubular WJ reactor 12 is filled with the processed liquid, and this high-speed jet is a submerged water jet with intense cavitation ( (Cavitation jet) 15 The harmful substances are decomposed by the action of the severe cavitation, and the concentration of the contained harmful substances decreases.

The purification treatment liquid (treatment liquid) 16 flowing out of the tubular WJ reactor 12 is sprayed onto the upper part of the adsorption tower 6, and flows down with the adsorbent 5 such as activated carbon adsorbing trichloroethylenes while flowing down the adsorption tower 6. Contact and elute trichlorethylene from activated carbon. The adsorption tower effluent (hazardous substance-containing liquid) 17 from the adsorption tower 6 contains a higher concentration of trichloroethylene than that discharged from the tubular WJ reactor 12 and is stored in the storage tank 9.
Return to The liquid 10 returned to the water storage tank 9 undergoes decomposition of trichlorethylenes again in the tubular WJ reactor 12 as necessary,
In addition, in the adsorption tower 6, the adsorbent 5 is used to remove trichlorethylene and the like. By repeating this operation, the amount of trichlorethylene adsorbed on the activated carbon is reduced and the activated carbon is regenerated and the adsorption capacity is increased, while the concentration of trichlorethylene in the liquid 10 in the water storage tank 9 is reduced. When the discharge criterion is satisfied, a neutralization treatment can be performed if necessary, and then the wastewater can be drained from the purified liquid discharge line 18.

The desorption of trichloroethylene from activated carbon is more likely to proceed as the temperature is higher, and hardly desorbs only by contact with water at about 20 ° C. In this regard, according to the present invention, the final treatment of trichloroethylenes can be performed extremely efficiently by performing the final treatment with WJ. That is, when the liquid 10 passes through the nozzle 13, the temperature of the liquid 10 rises, and varies depending on the total amount of liquid held in the system and the number of circulations of the liquid, but it is not possible to raise the temperature to about 50 ° C which does not exceed 60 ° C. Relatively easy. When the temperature rises in this manner, the decomposition of trichlorethylenes by WJ / cavitation proceeds most quickly, and the desorption of trichloroethylenes from activated carbon also proceeds rapidly. Of course, the liquid 10 in the water storage tank 9 or the purification treatment liquid 16 discharged from the tubular WJ reactor 12 and circulated and sprayed to the adsorption tower 6 can be heated to a predetermined temperature.

When the removal of the harmful substances from the activated carbon is completed, the operation is performed while returning the purification treatment liquid 16 discharged from the tubular WJ reactor 12 to the water storage tank 9, and when the discharge standard is satisfied, the purification liquid is discharged. Water will be drained from the pipe 18. Further, at the time when the detoxification of the harmful substances from the activated carbon and the detoxification of the liquid 10 in the water storage tank 9 are completed, the adsorbent 5 in the adsorption tower 6 is washed using cold and cold water 19 at normal temperature or lower, Cooling the adsorbent 5 and adjusting the solution for desorption in the next stage are excellent operational methods. The harmful substance treatment method of the present invention is not limited by the structure of the WJ / cavitation decomposition apparatus (eg, nozzle) and operating conditions (pressure, temperature, etc.).

That is, the basic technique of the present invention is to once adsorb a low-concentration harmful organic compound in a gas or a liquid to an adsorbent such as activated carbon, and then perform detoxification treatment using the generated cavitation. Activated carbon is an excellent adsorbent for various harmful organic compounds and is therefore suitable as a separating / concentrating agent, but how to regenerate it is an important issue. The method of the present invention utilizes the phenomenon that liquid temperature rises when cavitation is generated by WJ or ultrasonic method, desorbs harmful substances from adsorbent by liquid after cavitation treatment, and treats it again by cavitation It is.

According to the present invention, the decomposition of harmful substances by WJ / cavitation is performed according to the following principle. In other words, when high-pressure water is blown into the water from the nozzle as a high-speed jet, intense cavitation occurs,
When the cavitation bubbles collapse, an extremely high temperature and pressure are generated, and a large impact pressure acts. At this time, the chemical substance undergoes thermal decomposition and oxidation reaction. The oxidation reaction is thought to be caused by -OH radicals generated by thermal decomposition of oxygen and water present in the cavitation bubbles. And many harmful organic compounds such as trichlorethylene are decomposed into harmless compounds without using special chemicals.

The harmful substance treatment apparatus shown in FIG.
In the case of intermittent operation as a tower, as another embodiment of the present invention, as shown in FIG.
It is possible to adopt a system configuration in which a tower is installed and one of the adsorption towers is used for adsorbing harmful substances and the other adsorption tower is used for desorbing harmful substances. In this case, while the harmful substances are being adsorbed using the first adsorption tower 6A, the adsorbent 5B in the second adsorption tower 6B is used.
Is performed, and the effluent 17B from the second adsorption tower 6B is subjected to a detoxification process by WJ / cavitation.

The basic principle of the present invention lies in the detoxification treatment by adsorption of harmful substances with activated carbon and cavitation. As a specific means for generating cavitation, an ultrasonic method can be used instead of WJ.

The present invention can be widely used as a method for treating harmful substances which are adsorbed on activated carbon or the like and are decomposed by cavitation. Examples of the compound include the following examples. An aromatic compound, which has a hydroxyl group (-OH), a carboxyl group (-COOH), an alkyl group (-R), an ester group (-
COOR), aldehyde group (-COH), ketone group (-COR),
Ether group (-OR), halogen (-F, -Cl, -Br, -I),
A compound having at least one substituent such as an amino group (—NH ₂ ), a nitro group (—NO ₂ ), a sulfonic acid group (—SO ₃ H),
Dichloromethane, carbon tetrachloride, 1,2-dichloroethane,
1,1-dichloroethylene, cis-1,2-dichloroethylene, 1,1,1-trichloroethane, trichloroethylene,
Examples include halogenated carbons such as tetrachloroethylene and 1,3-dichloropropene, halogenated compounds such as PCB and dioxins, and CS bond-containing compounds such as thiuram.

[0028]

According to the present invention, a harmful substance present at a low concentration in a fluid is adsorbed by the adsorbent, and the harmful substance-containing liquid is circulated while purifying by cavitation to regenerate the adsorbent. The system can purify harmful substances by preventing the occurrence of secondary pollution.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing another embodiment of the present invention.

[Explanation of symbols]

 1 Purification target point 2 Soil gas suction well 3 Vacuum pump 4,4A, 4B Trichlorethylene-containing gas 5,5A, 5B Adsorbent 6 Adsorption tower 6A First adsorption tower 6B Second adsorption tower 7,7A, 7B Purified gas discharge pipe Channel 8 High-pressure pump 9 Reservoir 10 Liquid 11 High-pressure hose 12 Tube-type WJ reactor 13 Nozzle 14 Nozzle mount 15 Cavitation jet 16 Purification treatment liquid 17, 17A, 17B Adsorption tower effluent 18 Purification liquid discharge pipe 19 Cold water

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazunori Fujita 3-36 Takara-cho, Kure-shi, Hiroshima F-term in Babcock Hitachi, Ltd. Kure Research Laboratories 4D012 CA20 CB12 CB16 CD08 CG01 CH10 CJ05 CK10 4D024 AA04 AA10 AB04 AB11 AB13 BA02 BC01 CA01 DA08 DB06 DB10 4D037 AA11 AB11 AB12 AB13 AB14 AB16 BA26 BB07 CA01

Claims (7)

[Claims] 1. A method for adsorbing harmful substances in a fluid to an adsorbent.
Step 1 and a second step of desorbing the harmful substance from the adsorbent
The step of, and a harmful substance treatment method including a third step of purifying the harmful substance-containing liquid obtained in the second step,
In the third step, the harmful substance-containing liquid is purified by cavitation and the treatment liquid is sent to the second step, and in the second step, the harmful substance is removed from the adsorbent using the treatment liquid. A method for treating harmful substances, comprising desorbing substances. 2. The method for treating harmful substances according to claim 1, wherein the cavitation in the third step is generated by a water jet or an ultrasonic method. 3. The harmful substance processing method according to claim 1, wherein the processing liquid in the third step is heated to a temperature not exceeding 60 ° C. 4. The method for treating harmful substances according to claim 1, 2 or 3, wherein the second step comprises supplying clean and cold water to the adsorbent to which the harmful substances have been adsorbed, And removing the harmful substance from the adsorbent. 5. The method for treating harmful substances according to claim 1, wherein the harmful substance is an aromatic compound, and a hydroxyl group (—OH) and a carboxyl group (—COOH) with respect to a benzene nucleus. ), Alkyl group (-R), ester group (-COO
R), aldehyde group (-COH), ketone group (-COR), an ether group (-OR), halogen (-F, -Cl, -Br, -I ), amino group (-NH _2), a nitro group ( -NO ₂ ) or a compound having at least one substituent consisting of a sulfonic acid group (-SO ₃ H); dichloromethane, carbon tetrachloride, 1,2-dichloroethane, 1,1-dichloroethylene, cis-1,2 -Halogenated compounds consisting of dichloroethylene, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene or 1,3-dichloropropene, PCBs or halogen compounds consisting of dioxins and CS consisting of thiuram
A method for treating harmful substances, comprising a bond-containing compound. 6. A method for treating a harmful substance according to claim 1, wherein the harmful substance-containing liquid is contained therein, and the harmful substance-containing liquid is purified while the harmful substance-containing liquid flows out. An adsorption tower for desorbing the harmful substance from the adsorbent with the treatment liquid, and a reactor for inserting a nozzle, cavitating and cleaning the harmful substance-containing liquid by the nozzle, and sending the treatment liquid to the adsorption tower. A harmful substance processing apparatus characterized by comprising: 7. The harmful substance processing apparatus according to claim 6, further comprising a plurality of adsorption towers.