JP2010240594A - Decomposition treatment method of contaminated soil and contaminated ground water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely, effectively and economically treat contaminated soil and contaminated ground water contaminated by an organic chlorine compound, benzene or oil or the like, at the actual place. <P>SOLUTION: In the treatment method for decomposing contaminants on the actual place with the ground where soil and ground water are contaminated by the contaminants as a target, an injection well 1 capable of injecting a chemical agent to the ground of a contaminated area and the periphery is set, and a chemical treatment process of oxidatively decomposing the contaminants by injecting a chemical oxidizing agent from the injection well is executed. After a contamination concentration is reduced to some extent by the chemical treatment process, a biotreatment process of decomposing the contaminants further by microorganisms by injecting a microorganism activator from the injection well further is executed. The chemical treatment process and the biotreatment process may be repeatedly executed corresponding to contamination conditions. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a treatment method for decomposing a pollutant on the ground for a ground in which soil and groundwater are contaminated with a pollutant such as an organic chlorine compound, benzene, and oil.

The following methods have been put to practical use as this type of treatment method.
・ Iron powder method A method of reducing and decomposing organochlorine compounds in soil and groundwater by injecting zero-valent iron powder into the ground as a slurry or injecting iron powder into the ground while stirring the soil with a stirrer.
・ Bioremediation method A method of injecting microbial nutrients into contaminated soil or contaminated groundwater, activating indigenous microorganisms, and decomposing pollutants by microbial reaction.
・ Chemical oxidation method Oxidizing agent such as hydrogen peroxide and catalyst such as iron are injected into contaminated groundwater or chemicals are injected while stirring with a stirrer to chemically oxidize pollutants such as organochlorine compounds and benzene. Disassembling method.

  Further, Patent Document 1 proposes a purification method in which contaminated soil is cleaned in situ and then bioprocessed in situ after purifying oil-contaminated soil.

JP 2004-298830 A

Each of the above conventional treatment methods is useful for each, and many achievements are being made. However, there are still many problems to be solved in order to treat contaminated soil and contaminated groundwater efficiently and economically.
For example, in soil / groundwater contamination, the concentration of contaminants in soil and groundwater is often uneven, and a very high concentration of contaminated areas (plums) may exist locally. In addition, there are few cases where there is a single pollutant, and there are many cases where it is complex pollution due to multiple pollutants, and there are various groundwater qualities (dissolved oxygen, redox potential, various dissolved ions, etc.) that affect treatment effects Even in the same site, the contamination concentration may change over time.
Therefore, according to the above conventional treatment method, a sufficient treatment effect cannot be obtained especially in the case as described above, the treatment cannot be achieved in a predetermined construction period, and the purification cost is significantly increased from the initial plan. It is assumed that problems such as

  Moreover, although the purification method shown in Patent Document 1 is considered to be more effective than a case where the cleaning treatment and the biotreatment are combined to implement them alone, in order to implement it, an injection pipe, It is necessary to connect pumping, pumping, aeration, and gas suction means to each pipe after setting up one set of pumping pipes, aeration pipes, and gas suction pipes. Not only is it necessary to pump groundwater while injecting water and nutrient salts, but it is also necessary to aerate the groundwater and apply slight vibrations to the soil in order to obtain a sufficient cleaning effect. It is inevitable that a great deal of cost and labor is required for the operation, and it has not been widely spread.

  As described above, at present, no effective and appropriate means for treating contaminated soil and contaminated groundwater is provided, and it is effective to reliably and effectively treat contaminated soil and contaminated groundwater. The development of appropriate means is desired.

In view of the above circumstances, the present invention is a treatment method for decomposing a pollutant in the field on the ground in which soil and groundwater are contaminated by a pollutant such as an organic chlorine compound, benzene, and oil. An injection well capable of injecting a drug is provided in the area and the surrounding ground, and a chemical treatment step is first performed to oxidatively decompose contaminants by injecting a chemical oxidant from the injection well, and the chemical treatment After the contamination concentration is reduced by the process, a biotreatment process is further performed in which the microbial activator is further injected from the injection well to further decompose the contaminants with the microorganisms.
In the present invention, it is also conceivable to repeat the chemical treatment step and the biotreatment step according to the contamination status.

  The present invention combines a chemical treatment step that requires an expensive drug but an excellent treatment speed with a biotreatment step that can use an inexpensive drug that is inferior in the treatment speed, It has the advantages of both bioprocessing steps, and it can reduce the cost of the drug while ensuring the processing efficiency as a whole, and can be economically processed.

It is a schematic diagram which shows the condition which decomposes | disassembles the contaminated soil and the contaminated groundwater by the method of this invention.

  The present invention combines a chemical treatment process by a chemical oxidation method and a bio-treatment process by microorganisms to decompose pollutants (organochlorine compounds, benzene, oil, etc.) locally, but as equipment for that purpose In this case, it is possible to obtain an excellent treatment effect by simply injecting the chemicals necessary for each step from the injection well only by installing a water injection well used in common for both treatment steps.

FIG. 1 shows a situation where a contaminated area is processed by the processing method of the present invention.
In the treatment method of the present invention, as shown in FIG. 1, a plurality (five in the figure) of injection wells 1 are provided around and around the contaminated area, and the injection pump 4 is used to supply the two chemical reservoirs 2 and 3 installed on the ground surface. The drug can be injected into each injection well 1 via the injection line 5.
The chemical reservoir 2 is for storing a chemical oxidant (for example, hydrogen peroxide, sodium persulfate, etc.) that is a chemical injected during the chemical treatment process, and the chemical reservoir 3 is used during the biotreatment process. This is for storing a microbial activator (nutrient, etc.) which is a drug to be injected, and a drug can be selectively injected into the injection well 1 from either one of these drug reservoirs 2 and 3.

  In the treatment method of the present invention, a chemical treatment step is first performed by injecting a chemical oxidant from the chemical reservoir 2, thereby quickly decomposing the contaminants and rapidly reducing their concentration, and then the chemicals. Basically, the process proceeds to a bio-processing step by injecting a drug from the storage tank 3, thereby further decomposing the contaminant and further reducing its concentration.

In the present invention, the chemical treatment step carried out in the first stage can decompose the pollutants more quickly than the biotreatment step carried out in the latter stage, but the chemicals used for it are not cheap and therefore the treatment period is long. In such a case, an expensive drug must be injected in a large amount over a long period of time, which requires a large amount of drug cost, and thus an economical treatment is not desired.
On the other hand, the biotreatment process carried out later is inferior to the chemical treatment process in degrading the pollutants, and is particularly long for degrading to a sufficiently low concentration when the pollutants are at a high concentration. Although it takes a long period of time, the drugs required for it are inexpensive, so even if it is carried out continuously over a long period of time, it does not impose a significant burden on the cost.

Therefore, in the present invention, first, the chemical treatment process rapidly decomposes the high-concentration pollutant, and when it reaches a certain low concentration, it switches to the bio-treatment process, thereby reducing the drug cost while ensuring the overall processing efficiency. It becomes possible to reduce.
That is, the present invention rationally combines a chemical processing step that requires an expensive drug but has an excellent processing speed with a bioprocessing step that can use an inexpensive drug that is inferior in processing speed. It combines the advantages of both a chemical treatment process and a biotreatment process.

According to the trial calculation for examining the effect of the present invention, the case where the chemical treatment step and the biotreatment step are combined as described above is compared with the case where the normal chemical treatment step is processed alone. Then, the period required to obtain the same processing effect is about 10 to 15% longer for the former than the latter, but the processing cost required for that is reduced by 25 to 30%, which is sufficient from the viewpoint of cost effectiveness. It has been confirmed that it is effective.
Of course, in order to carry out the present invention, it is only necessary to provide an injection well 1 around the contamination area including the contaminated area so that two kinds of drugs can be selectively injected therein. No complicated and large-scale equipment is required, and there is no need for any troublesome operation or complicated control other than the medicine switching operation. In this respect, the present invention is sufficiently simple and economical. It is extremely effective.

  In general, a sufficient treatment effect can be obtained by shifting from the chemical treatment step to the biotreatment step as described above. However, depending on the conditions such as the type of contaminant, contamination status, soil properties, etc. However, an appropriate change is also possible, for example, after shifting from the chemical treatment step to the biotreatment step as described above, returning to the chemical treatment step again and further shifting to the biotreatment step. It is also conceivable to repeat the cycle of the biotreatment process as many times as necessary, thereby enabling more effective treatment.

1 Injection well 2, 3 Drug storage tank 4 Infusion pump 5 Infusion line

Claims (2)

A treatment method for decomposing pollutants on the ground on the ground where soil and groundwater are contaminated by pollutants such as organochlorine compounds, benzene and oil,
An injection well capable of injecting a drug is provided in the contaminated area and the surrounding ground, and a chemical treatment process is first performed to oxidatively decompose the contaminant by injecting a chemical oxidant from the injection well.
Contaminated soil and contamination characterized in that after the contamination concentration is reduced by the chemical treatment step, a biotreatment step of further decomposing the contaminant with microorganisms is performed by further injecting a microbial activator from the injection well. Groundwater decomposition method.   The method for decomposing and treating contaminated soil and contaminated groundwater according to claim 1, wherein the chemical treatment step and the biotreatment step are repeated.

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