JP2000093738A - Solvent gas treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently separating an organic solvent gas from a gas containing organic solvent gases. SOLUTION: This solvent gas treatment method includes combined processes for separating at least one organic solvent gas from a gas containing organic solvent gases: a process (a dissolving-in-water process) for dissolving a part of the contained organic solvent gases in water by bringing the organic solvent gas-containing gas into contact with water and a process (a biological treatment process) of biologically decomposing at least a part of the organic solvent gases by bringing the organic solvent gas-containing gas into contact with activated sludge-containing liquid. Consequently, an organic solvent gas can industrially and efficiently be separated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel solvent gas treatment method combining dissolution in water and biological decomposition treatment, preferably by contacting a gas containing an organic solvent gas, for example, exhaust gas, with an aqueous solution mainly containing water. And a method for effectively separating an organic solvent gas in a gas by contacting the organic solvent gas with an activated sludge solution.

[0002]

2. Description of the Related Art As a method for separating or decomposing an organic solvent in an exhaust gas containing an organic solvent, a method of directly burning, a method of burning using a heat storage type medium (heat storage combustion method), or adsorption of activated carbon or the like A method of adsorbing and recovering using an agent is known.

As a method for removing odors, such as sewage, which is not an organic solvent, a treatment method using microorganisms is known. For example, Japanese Patent Application Laid-Open No. 5-123527 discloses a method for efficiently deodorizing exhaust gas containing odor components using excess sludge.

[0004]

Of the above-mentioned conventional methods, the combustion method is expensive, and the regenerative combustion method requires an auxiliary fuel unless the gas concentration exceeds 500 ppm. Yes, running costs increase. In addition, although the method using sludge is used as a method for deodorizing odors in sewers, etc., its application method is not known for treating exhaust gas containing an organic solvent gas, and until the practical use. Has not arrived.

An object of the present invention is to develop an industrially superior method for separating, removing or recovering an organic solvent from a gas containing the organic solvent, for example, exhaust gas.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, a gas containing an organic solvent gas was first brought into contact with water to dissolve a part of the solvent gas in water. And then subjecting the gas containing the remainder of the solvent gas obtained after the step to a process of contacting with activated sludge and subjecting the solvent gas to a biologically decomposing treatment step, thereby greatly reducing the organic solvent gas. They have found that they can be efficiently separated and recovered as needed, and have completed the present invention based on this finding. The present invention solves the above-mentioned problems and separates organic solvent-based exhaust gas, particularly water-soluble solvent exhaust gas, with water and microorganisms contained in sludge, and performs treatment while collecting it as necessary. .

That is, in the present invention, when separating at least one kind of the solvent gas from the gas containing the organic solvent gas, the gas containing the organic solvent gas is brought into contact with water to partially dissolve the solvent gas in the water. A solvent gas treatment including a step (dissolution step in water) and a step of contacting a gas containing an organic solvent gas with an activated sludge solution and biologically decomposing at least a part of the solvent gas to be contacted (biological treatment step). Is the way.

[0008] One or more organic solvent gases may be contained, and when a plurality of solvent gases are separated, the above treatments can be combined simultaneously for a plurality of solvent gases, or the separation of a specific solvent gas can be performed. It can also be processed for the purpose.

It is possible to combine a plurality of the above two steps, or to combine the above two steps used in the present invention with another third treatment step in order to more efficiently separate the organic solvent.

In the underwater dissolution step, the water to be brought into contact with water is not limited to water, but may be in the form of an aqueous solution, as long as there is at least water for absorbing the solvent gas. Further, various additives such as surfactants, inorganic salts, various organic compounds and the like may be added and mixed to improve the solubility. Further, the organic solvent gas to be treated may already contain a part of the organic solvent gas and may be used as an aqueous solution for the treatment.

As a microbiological treatment method, a known activated sludge method using microorganisms may be used (see “Maintenance and management technology of activated sludge method” published by the Science and Technology Development Center).

Further, the following contents are also included in the present invention. 1. The above treatment method, wherein a biological treatment step is performed after the underwater dissolution step, and at least a part of the solvent gas is recovered from water or an aqueous solution in which the solvent gas is dissolved in the underwater dissolution step.

Before the organic solvent gas is decomposed by the biological treatment, the organic solvent gas to be separated is dissolved as much as possible into this water or an aqueous solution containing water by utilizing water, and if necessary, this is recovered. This is preferable because the decomposition treatment efficiency of the biological treatment can be increased and the solvent can be recovered.

As a method for recovering from the aqueous solution, a conventionally known or commonly used method for removing the organic part substance from water can be used.

2. The above treatment method, wherein the step of recovering at least a part of the solvent includes a step of heating water or an aqueous solution in which the solvent gas is dissolved to separate the solvent therefrom. Here, the heated and vaporized gas can be recovered as a liquid by condensation.

As a further preferred embodiment of the present invention, the following method can be mentioned. I. In a biological treatment method in which an organic solvent gas is decomposed using microorganisms, a part of the solvent gas is dissolved in a main solution of water, and then the solvent gas is separated from the solution in which the solvent gas is dissolved. Is a method in which the separated gas is condensed and separated, while the gas that is not dissolved in water is brought into gas-liquid contact with the activated sludge liquid to decompose and treat the solvent gas.

B. Above a. A method of treating the solvent gas by using a method of heating the solution as a method of releasing the solvent gas from the solution in which the solvent gas is dissolved in the method of the above.

C. A method for treating a solvent gas by treating in a gas-liquid contact with the activated sludge liquid using a treatment tower having a plurality of perforated plates therein.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to FIGS. 1 to 3, but the present invention is of course not limited to these.

FIG. 1 is a schematic diagram showing one embodiment of the present invention. As shown in FIG. 1, a gas 2 such as air containing a solvent gas is fed in from the lower part of the processing tower 5, and an aqueous solution containing water as a main component is sent in from the upper part.

As the aqueous solution, various additives as described above,
For example, surfactants, inorganic salts, various organic compounds, and the like may be added. Further, an organic solvent component may already be contained.

A plate tower, a wet wall tower, a packed tower, or the like can be used as the treatment tower 5 in order to increase the contact efficiency.

The superficial velocity of the gas 2 in the tower is 0.05 to 1
0 m / sec, and the average sectional velocity of the aqueous solution in the tower is 0.01 to 10 m / sec.

As the solvent which is a component of the solvent gas, various organic solvents which can be absorbed by water are applicable. For example, many water-soluble solvents such as methanol, ethanol, methyl ethyl ketone, methyl isobutyl ketone, acetone, propyl alcohol and isopropyl alcohol are available. Although a solvent can be mentioned, the kind of the solvent is not limited to those listed here.

A solvent component having low water solubility may be contained in the gas together with the water-soluble or water-soluble solvent, or may be contained as long as it can be absorbed by water.

The applied gas concentration is 適用 5000
ppm, more preferably about 3500 ppm.

The aqueous solution 4 after the gas-liquid contact is heated in the tank 3 at about 50 to 250 ° C., degassed, liquefied in the condenser 8 and collected in the tank 9. Hot water or various heat media is used for heating.

The solvent gas 7 that has not been dissolved in the aqueous solution is led to the treatment tower 11, where it comes into gas-liquid contact with the activated sludge liquid, and the solvent gas is decomposed. For the treatment or the like 11, a tray tower or the like having a plurality of perforated plates therein to increase the contact efficiency can be used.

Next, another embodiment of the present invention (FIG. 2)
reference. 1), a pipe 17 having a heating mechanism or a packed tower is used in place of the tank 3 in the method of FIG. 1 described above, and remains in the gas without being absorbed by water in the gas-liquid contact in the processing tower 5. A pipeline mixer 11 'can be used as a contact device between the solvent gas and the sludge liquid. This method is preferable in that the mud containing efficiency can be increased with a small capacity.

Further, an example of another embodiment of the present invention (FIG. 3)
reference. As (1), a tank 18 with a diffuser pipe 19 can be used as a contact device between the solvent gas that has not been dissolved in the aqueous solution in the first gas-liquid contact and the sludge liquid. This method is preferable in that existing facilities conventionally used for domestic wastewater and the like can be utilized.

[0031]

The present invention will be described below in detail with reference to examples.

Example 1 A gas containing methanol as an organic solvent gas was processed based on the processing system shown in FIG.

In FIG. 1, 1500 ppm of methanol
The contained air 2 is supplied to the lower part of the processing tower 5 and 25
1 ° C. water 1 is supplied. The air tower speed is 0.8m /
sec, average cross section speed in water tower is 0.1m / sec
c. The aqueous solution 4 containing methanol flowing out of the processing tower 5 is heated in the tank 3 to a temperature inside the tank of 85 ° C., and methanol gas is separated. The separated gas is condensed in the condenser 8, liquefied and collected in the tank 9.

On the other hand, methanol gas 7 that cannot be completely dissolved in water is supplied to the lower part of the processing tower 11. The activated sludge liquid 16 is supplied to the upper part of the processing tower 11. At this time, the methanol concentration of the gas 7 was 300 ppm. The superficial velocity of the gas 7 in the treatment tower 11 is 0.79 m / sec, and the average sectional speed of the activated sludge liquid in the tower is 0.1 m / sec.

The methanol concentration of the air 14 discharged from the processing tower 11 was 30 ppm. As is clear from the above results, it was found that the methanol gas contained in the gas can be efficiently separated and recovered by the method of the present invention.

[Example 2] In Example 1, the treatment was carried out using air containing 1100 ppm of isopropyl alcohol gas instead of methanol gas as the organic solvent gas.

In FIG. 1, this air is supplied to the lower part of the processing tower 5 and water at 20 ° C. is supplied from the upper part. The air tower speed is 0.7 m / sec, and the average sectional speed in the water tower is 0.15 m / sec. The aqueous solution containing isopropyl alcohol flowing out of the processing tower 5 is heated in the tank 3 so that the tank internal temperature becomes 90 ° C., and the isopropyl alcohol gas is separated. The separated gas is condensed and liquefied in the pipe 8 and collected in the tank 9.

On the other hand, the gas 7 that cannot be completely dissolved in water is
Supplied to the bottom. The upper part of the tower 16 is supplied with the activated sludge liquid. At this time, the concentration of the isopropyl alcohol gas 7 was 350 ppm. The superficial velocity of the gas 7 in the treatment tower 11 is 0.69 m / sec, and the average sectional speed of the activated sludge liquid in the tower is 0.15 m / sec. The isopropyl alcohol concentration of the air 14 discharged from the processing tower 11 was 40 ppm.

As is evident from the above results, the method of the present invention makes it possible to efficiently separate and recover isopropyl alcohol from a gas containing isopropyl alcohol.

[0040]

From the above description and the results of the examples, when separating the organic solvent gas from the gas containing the organic solvent gas, the organic solvent gas-containing gas is brought into contact with water to partially remove the solvent gas into the water. Two steps of a dissolving step (a dissolving step in water) and a step of bringing an organic solvent gas-containing gas into contact with an activated sludge and subjecting at least a part of the solvent gas to be contacted to biological decomposition treatment (a biological treatment step). It can be understood that the solvent gas can be industrially efficiently separated from the gas containing the organic solvent gas and recovered as necessary by the solvent gas treatment method according to the present invention in which the solvent gas is used.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention.

FIG. 2 is a schematic view showing another embodiment of the present invention.

FIG. 3 is a schematic view showing still another embodiment of the present invention.

[Explanation of symbols]

3 tanks; 5 processing towers; 8 condensers: 9 tanks; 1
0 fan; 11 processing tower; 11 'pipeline mixer; 12 tank; 13 pump; 17 pipe;
Tank; 19 diffuser

Claims (3)

[Claims] 1. A method of separating at least one kind of solvent gas from a gas containing an organic solvent gas by contacting the gas containing an organic solvent gas with water to dissolve a part of the solvent gas in water (water A dissolving step) and a step of contacting a gas containing an organic solvent gas with the activated sludge liquid to biologically decompose at least a part of the solvent gas (biological treatment step). Gas treatment method. 2. The method according to claim 1, wherein a biological treatment step is performed after the underwater dissolution step, and at least a part of the solvent gas is separated from water or an aqueous solution in which the solvent gas is dissolved in the underwater dissolution step. 3. The processing method according to claim 2, wherein the step of separating at least a part of the solvent includes a step of heating water or an aqueous solution in which the solvent gas is dissolved to separate the solvent.