JP2000042524A - Method for degrading contaminant in soil and/or underground water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To degrade contaminants in soil and/or underground water without requiring power energy by bringing an anion exchange resin into contact with the soil and/or underground water and leaching a material which promotes the degradation of the contaminants from the anion exchange resin. SOLUTION: An anion exchange resin is brought into contact with soil and/or underground water by a method such as embedding in the soil. The anion exchange resin is preferably obtd. by introducing quat. ammonium or amino groups as exchange groups into a styrene-divinylbenzene copolymer as a substrate. The ammonium or amino groups are leached as methanol or amine which promotes the propagation of contaminant degrading microorganisms such as tetrachloroethylene degrading bacteria and contaminants are efficiently degraded and removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently decomposing pollutants in soil and / or groundwater on site.

[0002]

2. Description of the Related Art Soil and groundwater may be contaminated with various harmful hardly decomposable substances. Above all, pollution by an organic chlorine compound such as tetrachloroethylene (PCE) or a petroleum organic compound has become a serious problem.

Conventionally, since these pollutants have a high volatility, they are taken out from soil or groundwater by absorbing soil gas or by pumping groundwater for volatilization, and the activated carbon is collected on the ground. It is processed by performing adsorption processing. However, these methods require a large amount of energy for pump power for gas suction and pumping, and are expensive.

As a method of purifying contaminated soil and groundwater with relatively little power, a method of decomposing pollutants on site has attracted attention. In this decomposition treatment method, microorganisms are activated by supplying a growth substrate to the soil,
A method of decomposing pollutants by the action of microorganisms and a method of oxidatively decomposing pollutants by supplying an oxidizing agent to soil are being studied. However, in either case,
It is necessary to continuously supply the soil with substances that promote the decomposition of contaminants such as growth substrates and oxidants, and again, power energy for intermittently or continuously supplying the decomposition promoting substances is required. Become.

On the other hand, as a method that does not require motive energy during treatment, a method of burying metallic iron in soil and decomposing contaminants that come into contact with the metallic iron has been studied. However, in this method, various competitive reactions occur, and the decomposition reaction of pollutants may be inhibited by corrosion of metallic iron.

A method of decomposing contaminants by burying biodegradable plastic in soil and activating microorganisms by eluted organic matter has been studied. However, since biodegradable plastic is expensive, it is not practical. It has not been converted.

[0007]

As described above, a practical method capable of decomposing a contaminant in soil or groundwater at a site in the past, and a method that does not require motive energy during the treatment is known. Not provided.

[0008] The present invention removes contaminants in soil and groundwater.
It is an object of the present invention to provide a method for decomposing pollutants in soil and / or groundwater that can be efficiently decomposed on site without requiring motive energy during the process.

[0009]

The method for decomposing contaminants in soil and / or groundwater according to the present invention comprises contacting an anion exchange resin with soil and / or groundwater to promote decomposition of contaminants from the anion exchange resin. Eluted substances, and decompose contaminants in soil and / or groundwater by the substances.

When the anion exchange resin is brought into contact with soil and / or groundwater, decomposition products of the anion exchange resin and substances previously adsorbed on the anion exchange resin elute into the contaminated soil and / or groundwater. When the eluted substance is a growth substrate for microorganisms such as organic substances, the microorganisms in the soil are activated by the eluted substance and the contaminants are decomposed. In addition, for example,
In the case of an oxidizing agent such as permanganate ion, the pollutant is decomposed by the oxidation reaction.

[0011] In the present invention, the kinetic energy during the treatment is obtained by burying the anion exchange resin in the soil or by contacting the anion exchange resin with the soil and / or groundwater by immersing the resin in the well water. It is possible to efficiently decompose and remove contaminants in soil and / or groundwater without the need for supplying water.

In the present invention, the anion exchange resin is preferably an organic anion exchange resin, particularly an anion exchange resin obtained by chemically modifying a copolymer of styrene and divinylbenzene.

[0013]

Embodiments of the present invention will be described below in detail.

The anion exchange resin used in the present invention is preferably an organic anion exchange resin in which a copolymer of styrene and divinylbenzene is used as a base and a quaternary ammonium group or an amino group is introduced as an exchange group.
A strong basic anion exchange resin in which the anion exchange resin is Cl-type, and an organic acid such as lactic acid, acetic acid, propionic acid, butyric acid, and isobutyric acid, and an oxidizing agent such as potassium permanganate are adsorbed on the anion exchange resin. Are preferred.

In such an anion exchange resin, for example, when the anion exchange resin is decomposed, the styrene-divinylbenzene copolymer and the ammonium group or amino group introduced as an ion exchange group are replaced with methanol or amine. Eluted, and these eluted substances
It promotes the growth of pollutant-degrading microorganisms such as CE-degrading bacteria, and efficiently decomposes and removes pollutants in soil and / or groundwater.

In addition, since pollutant-decomposing microorganisms such as decomposing bacteria are multiplied by an organic acid such as lactic acid, when an anion exchange resin to which an organic acid is adsorbed is used, the microorganism is gradually released from the anion exchange resin. Pollutant-decomposing microorganisms such as decomposing bacteria are proliferated by the organic acid, and the decomposition of pollutants in the soil is promoted.

Further, since an organic chlorine compound is chemically decomposed by an oxidizing agent such as potassium permanganate, the use of an anion exchange resin having such an oxidizing agent adsorbed thereon allows the anion exchange resin to be gradually decomposed. The released oxidant can decompose contaminants.

In the case of using an anion exchange resin to which an organic acid or an oxidizing agent is adsorbed, the amount of adsorption is not particularly limited. In order to maintain the effect for a long time, the larger the amount of adsorption, the more preferable.

In the present invention, the method of bringing soil and / or groundwater into contact with the anion exchange resin is not particularly limited. However, the method of contacting the soil with the anion exchange resin is less than the method of collecting the soil and mixing the anion exchange resin at another place. A method of burying an anion exchange resin or immersing the anion exchange resin in well water and treating it on site is preferable. Specifically, for example, the following method can be adopted.

A hole is dug in the ground made of the contaminated soil, and an anion exchange resin is charged into the hole and buried. Contaminated soil is dug up and backfilled after mixing with anion exchange resin. The anion exchange resin is immersed in well water at the bottom of an existing or newly drilled well. A pipe with many holes is driven into the ground, and the pipe is filled with an anion exchange resin. An anion exchange resin is packed in a water-permeable cloth bag and submerged at the bottom of the well. In this way, when the anion exchange resin is brought into contact with the soil and / or groundwater, the amount of the anion exchange resin used is appropriately determined according to the soil and / or groundwater contamination status and the like.

In the present invention, once the anion exchange resin is buried in the soil, it is simply left as it is.
Pollutants in the soil and / or groundwater can be decomposed and removed by decomposition promoters gradually released from the anion exchange resin. Can be decomposed and removed.

[0022]

The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Example 1 A strongly basic anion exchange resin having a styrene-divinylbenzene skeleton was treated with an aqueous sodium hydroxide solution to obtain an OH form. This OH type anion exchange resin is
It was immersed in a 0 g / L aqueous lactic acid solution to adsorb lactic acid. The adsorption amount of lactic acid was about 10% by weight based on the anion exchange resin.

Into a 155 mL vial, 70 mL of a solution (pH 7) containing tetrachloroethylene (PCE) prepared using tap water and having the composition shown in Table 1 and 10 mL of sludge acclimated to tetrachloroethylene (PCE) were poured. 50mL of anion exchange resin adsorbing lactic acid
Was suspended and the gas phase was replaced with nitrogen.

[0025]

[Table 1]

The vial was allowed to stand at 30 ° C., and the concentrations of chlorinated ethylenes and ethylene in the head space were analyzed by gas chromatography. The results are shown in FIG.

Example 2 In Example 1, the concentration of chlorinated ethylenes and ethylene was changed in the same manner as in Example 1, except that an anion exchange resin in the form of Cl with sodium chloride was used instead of the anion exchange resin on which lactic acid was adsorbed. Was analyzed, and the results are shown in FIG.

Comparative Example 1 The chlorinated ethylenes and ethylene concentrations were analyzed in the same manner as in Example 1 except that the anion exchange resin was not used, and the results are shown in FIG.

As apparent from FIGS. 1 to 3, the vials of Examples 1 and 2 in which the anion exchange resin was suspended
Although a dechlorinated product of CE was detected, a dechlorinated product of PCE was not detected in Comparative Example 1 in which no anion exchange resin was used. These results show that the anion exchange resin promotes the dechlorination reaction (decomposition reaction) of PCE.

[0030]

As described in detail above, the soil and / or
Alternatively, the method of decomposing contaminants in groundwater can efficiently decompose soil and / or groundwater contaminants on site without the need for power during treatment and therefore at low maintenance costs. Become.

[Brief description of the drawings]

FIG. 1 is a graph showing the state of decomposition of PCE when using an anion exchange resin on which lactic acid is adsorbed in Example 1.

FIG. 2 is a graph showing the state of decomposition of PCE when a Cl-type anion exchange resin in Example 2 was used.

FIG. 3 is a graph showing the decomposition state of PCE in Comparative Example 1 when no anion exchange resin was used.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B09C 1/10 ZAB

Claims (3)

[Claims] 1. An anion exchange resin is brought into contact with soil and / or groundwater to elute a substance that promotes the decomposition of pollutants from the anion exchange resin.
Alternatively, a method for decomposing contaminants in soil and / or groundwater, comprising decomposing contaminants in groundwater. 2. The method for decomposing pollutants in soil and / or groundwater according to claim 1, wherein the anion exchange resin is an organic anion exchange resin. 3. The soil and / or groundwater according to claim 2, wherein the organic anion exchange resin is an anion exchange resin obtained by chemically modifying a copolymer of styrene and divinylbenzene. How to decompose pollutants.