JP2009297617A - Method for improving contaminated soil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for improving contaminated soil which can easily carry out continuous purification of contaminated soil at a low cost over a long period of time. <P>SOLUTION: Cylinders 3 having water passage holes 2 are embedded in the ground 1 where the soil has been contaminated. An adsorbent 4 is housed in the cylinder 3 so as to be freely put in and out of the cylinder 3. Contaminants contained in groundwater infiltrating into the cylinder 3 through the water passage holes 2 are adsorbed by the adsorbent 4. The adsorbent 4 having adsorbed the contaminants is collected on the ground, and then the new adsorbent 4 is put into the cylinder 3. These operations are repeated to improve the contaminated soil. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for improving contaminated soil.

  Conventionally, patent document 1 is known as a contaminated soil improvement method, for example. In the conventional example shown in Patent Document 1, after the injection pipe is inserted into the contaminated ground, the contaminated soil is stirred by injecting water and air while rotating and pulling up the injection pipe. By discharging slurry-like bamboo charcoal powder and embedding the slurry-like bamboo charcoal powder in the space part of the contaminated soil discharged by spraying the slurry-like bamboo charcoal powder, heating the contaminated soil discharged on the ground to perform air bubble ring, The polluted gas contained in the contaminated soil discharged on the ground is separated, and the pollutant contained in the groundwater is adsorbed by the bamboo charcoal powder as the groundwater passes through the slurry-like bamboo charcoal powder part that is replaced and buried in the place where the contaminated soil was discharged. And purify it.

  However, in the above-described conventional example, the slurry-like contaminated soil is discharged to the ground to separate the contaminated gas, so that there is a problem that the contaminated soil improvement work becomes large and the cost becomes high. Further, the slurry-like contaminated soil needs to be disposed on the ground after separating the pollutant gas, and there is a problem that the disposal of the slurry-like soil is costly.

  Moreover, even if the contaminated soil is discharged to the ground and replaced with bamboo charcoal powder, the injection pipe is inserted into a small part of the contaminated soil where the soil is contaminated. The contaminated soil is not discharged to the ground and remains.

Therefore, in the above-mentioned conventional example, the slurry-like bamboo charcoal powder is replaced and buried in the part where the contaminated soil is discharged, so that the pollutants contained in the groundwater are adsorbed by the buried bamboo charcoal powder. If pollutants are adsorbed on the powder and the adsorption capacity of bamboo charcoal powder becomes saturated, then the pollutants contained in the groundwater cannot be adsorbed. Therefore, in the above conventional example, there is a problem that the purification treatment of the contaminated soil cannot be performed effectively for a long period of time.
JP 2005-211861 A

  This invention is invented in view of said conventional problem, Comprising: It aims at providing the contaminated soil improvement method which can perform purification of contaminated soil continuously over a long period of time at low cost. To do.

  In order to solve the above-mentioned problem, the contaminated soil improvement method according to the present invention embeds a cylinder 3 provided with water passage holes 2 in the ground 1 where the soil is contaminated, and puts the adsorbent 4 in the cylinder 3. The adsorbent 4 adsorbs the pollutant contained in the groundwater that has entered the cylinder 3 through the water passage hole 2 and adsorbs the adsorbent 4 adsorbing the pollutant on the ground. A new adsorbent 4 is placed in the cylindrical body 3 and this is repeated to improve the contaminated soil.

  By adopting such a method, the groundwater containing pollutants passes through the adsorbent 4 accommodated inside the cylinder 3 from the water passage hole 2 of the cylinder 3 embedded in the ground 1 and is contained in the groundwater. The contaminated soil is adsorbed by the adsorbent 4, and the ground 1 where the soil is contaminated is gradually improved. When the adsorbent 4 accommodated in the cylinder 3 adsorbs contaminants and approaches a saturated state, the adsorbent 4 that has approached the saturated state is recovered on the ground, and a new adsorbent is collected in the cylinder 3. 4 is put in again, and the contaminant contained in the groundwater is again adsorbed by the adsorbent 4 to continue the improvement of the contaminated ground 1. In this case, since the adsorbent 4 is housed in the cylinder 3 embedded in the contaminated ground 1 and recovered on the ground, the adsorbent 4 is recovered on the ground and a new adsorbent 4 is returned to the cylinder again. It is only necessary to store in 3 and the improvement of the contaminated ground 1 can be continued without discharging the contaminated soil to the ground as in the prior art. In addition, the adsorbent 4 collected on the ground can be used again as the adsorbent 4 by separating and collecting the pollutants. Of the pollutants separated and collected, those that can be reused as resources are collected. Can be reused. In addition, since it is not necessary to discharge the contaminated soil to the ground, there is no need to dispose of the contaminated soil on the ground. In other words, pollutants are eluted in the groundwater and gradually become below the pollution standard value.

  Moreover, it is preferable to store the water-permeable bag 5 containing the adsorbent 4 so as to be freely inserted into and removed from the upper end opening of the cylindrical body 3.

  By adopting such a method, the adsorbent 4 can be stored in the cylindrical body 3 embedded in the ground 1 and pulled up to the ground in a state where the adsorbent 4 is put in the water-permeable bag 5. The adsorbent 4 can be stored and pulled up in the cylinder 3 very easily.

  Moreover, it is preferable to inject the water selected between pH 4-10 in the ground 1 where the soil is contaminated.

  By adopting such a method, the amount of groundwater moved in the ground 1 where the soil is contaminated is increased, the amount of water passing through the adsorbent 4 stored in the cylinder 3 is increased, and more The adsorbent 4 can adsorb pollutants contained in the groundwater efficiently. In addition, by selecting the water quality at the time of water injection from pH 4 to 10 and injecting water, water having a pH suitable for the state of the pollutant in the contaminated soil (the compound of the pollutant in the contaminated soil differs depending on the site) Can be used to increase the elution of pollutant compounds. In addition, since the influence which it has on soil and worries about a side effect other than pH4-10 is chosen, it chooses between pH4-10.

  Moreover, it is preferable to pump up water that has entered the cylinder 3 in which the adsorbent 4 is stored.

  By adopting such a method, the groundwater in the ground 1 where the soil is contaminated can be collected in the cylinder 3 and the adsorbent 4 stored in the cylinder 3 can be passed through and pumped up. Thereby, the amount of water passing through the adsorbent 4 can be increased, and the pollutant contained in the groundwater can be adsorbed by the adsorbent 4 more efficiently.

  Since the invention according to claim 1 of the present invention is the method as described above, the adsorbent is recovered on the ground when the adsorbent stored in the cylinder embedded in the soil contaminated with soil is close to saturation. Then, it is only necessary to add new adsorbent again, and the purification of the contaminated soil can be performed continuously over a long period of time at low cost.

  According to the second aspect of the invention, in addition to the effect of the first aspect of the invention, the water-permeable bag containing the adsorbent is accommodated in and out of the cylinder from the upper end opening of the cylinder. Therefore, the operation of recovering the adsorbent stored in the cylinder to the ground or putting the adsorbent in the cylinder can be easily performed in a very short time because the adsorbent is put in the bag.

  In addition, in the invention according to claim 3, in addition to the effect of the invention according to claim 1 or 2, since the water is poured into the ground where the soil is contaminated, the adsorbent stored in the cylinder By increasing the amount of water to be passed, the pollutants contained in the groundwater can be more efficiently adsorbed by the adsorbent.

  In addition, in the invention according to claim 4, in addition to the effect of the invention according to any one of claims 1 to 3, water that has entered the cylinder containing the adsorbent is pumped up. The amount of water passing through the adsorbent can be increased to more efficiently adsorb the pollutants contained in the groundwater with the adsorbent.

  Hereinafter, the present invention will be described based on embodiments shown in the accompanying drawings.

In improving the contaminated soil in the present invention, first, a metal pipe, a synthetic resin pipe, and a ceramic industry system in which a large number of water holes 2 such as small holes and slits are provided on the outer periphery of the ground 1 where the soil is contaminated. A cylinder 3 such as a cylinder is embedded. A large number of cylinders 3 provided with the water passage holes 2 are buried at a pitch in the ground 1 where the soil is contaminated. The burying pitch of the cylindrical body 3 varies depending on the soil contamination state or the ground 1 state. For example, the cylindrical body 3 made of an iron pipe of φ10 cm provided with a large number of water holes 2 is 1 per 1 m ^2. Buried in the ground 1 at the rate of books. In this way, a large number of cylinders 3 provided with a large number of water passage holes 2 are embedded at a certain pitch almost all over the ground 1 in a region where the soil is contaminated.

  In these cylinders 3, adsorbents 4 such as zeolite, iron oxide, activated carbon and clay are stored. As shown in FIG. 1, the adsorbent 4 is placed in a water-permeable bag 5 and is detachably stored in the cylinder 3 from the upper end opening of the cylinder 3.

  The water-permeable bag 5 is formed of a nonwoven fabric, a woven fabric, a net, a perforated sheet provided with countless small holes, or the like. In addition, since the bag 5 is used for a long time, the one made of synthetic resin having excellent corrosion resistance is preferable. The water-permeable bag 5 is elongated in the vertical direction, and the adsorbent 4 is accommodated therein.

  Here, in the embodiment shown in FIG. 2, a plurality of pocket portions 5 a are vertically fixed by aligning both surfaces of the vertically elongated bag 5 at a plurality of locations in the downward direction and partially fixing them by bonding or heat welding. The adsorbent 4 is accommodated in each pocket portion 5a, whereby the adsorbent 4 can be accommodated in a balanced manner in each of the vertical portions of the elongated bag 5.

  A string 6 is attached to the upper end of the bag 5, and the string 6 is led upward from the upper opening of the cylinder 3.

  As described above, a large number of cylinders 3 provided with a large number of water passage holes 2 are embedded in the ground 1 where the soil is contaminated, and the adsorbent 4 is accommodated in the cylinders 3 so that the groundwater is cylindrical. 3 passes through the water passage hole 2 and passes through the adsorbent 4.

  Since the groundwater in the ground 1 in which the soil is contaminated contains (dissolves or mixes), the adsorbent 4 is used when the adsorbent 4 passes through the groundwater containing the pollutant. By 4, the pollutant contained in the ground water is adsorbed. If the concentration of pollutants in groundwater decreases, pollutants in contaminated soil will elute pollutants into groundwater due to chemical equilibrium. In this way, the pollutants in the soil gradually dissolve or mix in the groundwater, and the pollutants dissolved or mixed in the groundwater are gradually adsorbed by the adsorbent 4, thereby improving the soil 1 that is gradually polluted. Is done.

  Of the adsorbents 4 placed in a large number of cylinders 3, the adsorbent 4 put in one or several cylinders 3 is determined for monitoring and is used for a predetermined period (for example, 1 to several months). Each time, the adsorption state of the contaminants in the adsorbent 4 determined for the monitor is inspected. In other words, the adsorbent 4 is lifted from the cylinder 3 at the location determined for monitoring to the ground together with the bag 5, and the adsorbent 4 is inspected on the ground by inspecting the adsorption state of the contaminants to the adsorbent 4 determined for the monitor. An inspection for confirming the degree of saturation of the contaminant with respect to the material 4 is performed.

  As a result of the monitor inspection, if it is confirmed that the adsorbent 4 has not reached saturation and still has a sufficient adsorbing capacity, the adsorbent 4 pulled up to the ground for the inspection is put in the bag 5. The adsorbent 4 other than the monitor is kept in each cylinder 3 and continues to adsorb contaminants contained in the groundwater.

  On the other hand, if it is confirmed as a result of the monitor inspection that the adsorbent 4 has adsorbed contaminants and is approaching a saturated state, the adsorbent 4 accommodated in all the cylinders 3 is collected on the ground. In collecting the adsorbent 4 to the ground, the adsorbent 4 can be easily pulled up and collected by pulling the bag 5 to the ground. In this case, since the string 6 is attached to the upper end of the bag 5 and led out upward from the upper opening of the cylinder 3, the bag 5 placed in the cylinder 3 by pulling the string 6 can be easily put on the ground. Can be raised.

  After collecting the adsorbent 4 in which the adsorption of the pollutant is close to saturation as described above on the ground, the new adsorbent 4 is put in the bag 5 and the cylinder 3 is opened from the upper opening of each cylinder 3. The new adsorbent 4 is accommodated in a large number of cylinders 3 by being put inside.

  By storing the new adsorbent 4 in the cylindrical body 3 in this way, the pollutant contained in the groundwater again passes through the adsorbent 4 in the groundwater containing the pollutant in the same manner as described above. The pollutants contained in the groundwater are adsorbed by the newly replaced adsorbent 4.

  Then, when the adsorption capacity of the adsorbent 4 approaches saturation, the adsorbent 4 is again collected on the ground as described above, and the new adsorbent 4 is repeatedly placed in the cylinder 3. The soil improvement is completed when a contaminated soil sample is collected by boring at approximately the center position of the three groups of cylinders, analyzed, and a value equal to or lower than the reference value of contamination is obtained.

  As described above, according to the present invention, it is only necessary to collect the adsorbent 4 on the ground and store the new adsorbent 4 in the cylindrical body 3 again. Improvement of the contaminated ground 1 can be continued without discharging.

  On the other hand, the adsorbent 4 that adsorbs the contaminant collected on the ground is used again as the adsorbent 4 by separating and collecting the contaminant from the adsorbent 4 by any separation and collection means such as heat treatment or chemical treatment. Of the pollutants separated and collected, those that can be reused as resources, such as rare metals, are collected and reused.

  Next, another embodiment of the present invention will be described with reference to FIG.

  In the present embodiment, as in the above-described embodiment, a metal pipe, a synthetic resin pipe, and a ceramic industry system in which a large number of water holes 2 such as small holes and slits are provided on the outer periphery of the ground 1 where the soil is contaminated. In the ground 1 where the soil is polluted, a plurality of water supply pipes 7 are placed in the cylinder 3 and a bag 5 containing the adsorbent 4 is placed in the cylinder 3. Buried in

  Then, water is pressurized into the ground 1 from the water discharge holes 8 provided in the water supply pipe 7 and injected, thereby increasing the amount of movement of groundwater in the ground 1 where the soil is contaminated. The amount of water passing through the adsorbent 4 stored in the container is increased.

  In this way, by increasing the amount of water that is poured into the ground 1 and the adsorbent 4 is passed, the pollutants contained in the groundwater can be adsorbed by the adsorbent 4 more efficiently, The period required for soil improvement can be shortened.

  Since pollutant compounds in the contaminated soil vary depending on the site and exist in various ways, in order to increase the elution degree, it is preferable to select water having a pH suitable for it and inject water into the target ground 1.

  In this way, depending on the state of pollutants in the contaminated soil (compounds of pollutants in the contaminated soil vary depending on the site), the water quality at the time of water injection is selected between pH 4 and 10, and the water is contaminated. Water with a pH that is compatible with the material can be selectively used to increase the solubility of the pollutant compound.

  Of course, also in this embodiment, when the adsorbent 4 accommodated in the cylinder 3 adsorbs the contaminant and approaches the saturated state, the adsorbent 4 approaching the saturated state is recovered on the ground, and the cylinder 3 A new adsorbent 4 is placed inside, and the contaminated ground 1 is improved by adsorbing the pollutants contained in the groundwater to the adsorbent 4 while repeating this process many times.

  Still another embodiment of the present invention will be described with reference to FIG.

  In the present embodiment, as in the above-described embodiment, a metal pipe, a synthetic resin pipe, and a ceramic industry system in which a large number of water holes 2 such as small holes and slits are provided on the outer periphery of the ground 1 where the soil is contaminated. In addition, a bag 5 containing an adsorbent 4 is placed in the cylinder 3, and in addition, water that has entered the cylinder 3 containing the adsorbent 4 is placed in the cylinder 3. Is supposed to pump water. Various methods can be employed for pumping water. For example, the upper opening of the cylindrical body 3 is detachably shielded by the shielding lid 9 and the end is connected to the pump 10 in the hole provided in the shielding lid 9. By fixing the end portion of the pipe 11, the inside of the cylinder 3 is depressurized by operating the pump 10, and the water entering the cylinder 3 is pumped up.

  Thus, by pumping the water that has entered the cylinder 3 in which the adsorbent 4 is stored, the groundwater in the ground 1 where the soil is contaminated is collected in the cylinder 3 and stored in the cylinder 3. The adsorbent 4 can be pumped up and pumped up. As a result, the amount of water passing through the adsorbent 4 is increased, and the pollutants contained in the groundwater are more efficiently adsorbed by the adsorbent 4. can do.

  Of course, also in this embodiment, when the adsorbent 4 accommodated in the cylinder 3 adsorbs the contaminant and approaches the saturated state, the adsorbent 4 approaching the saturated state is recovered on the ground, and the cylinder 3 A new adsorbent 4 is placed inside, and the contaminated ground 1 is improved by adsorbing the pollutants contained in the groundwater to the adsorbent 4 while repeating this process many times.

  In the case of the embodiment in which water is pumped, the water supply pipe 7 may be embedded in the ground 1 and injected into the ground 1 together. In this case, the water is efficiently contained in the groundwater. Contaminants present can be adsorbed by the adsorbent 4.

It is sectional drawing of one Embodiment of this invention. It is sectional drawing of other embodiment same as the above. It is sectional drawing of other embodiment same as the above. It is sectional drawing of other embodiment same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ground 2 Water flow hole 3 Cylindrical body 4 Adsorbent

Claims (4)

  Pollution contained in groundwater that has been embedded in a cylinder with a water passage hole in the soil contaminated with soil, and that adsorbents can be taken in and out of the cylinder body, and has entered the cylinder body through the water passage hole. Contaminated soil characterized by adsorbing substances with adsorbents, collecting adsorbents adsorbing pollutants on the ground, placing new adsorbents inside the cylinder, and repeating this to improve contaminated soil Improvement method.   2. The method for improving contaminated soil according to claim 1, wherein a water-permeable bag containing an adsorbent is housed so as to be freely inserted into and removed from the upper end opening of the cylinder.   The method for improving contaminated soil according to claim 1 or 2, wherein water selected between pH 4 and 10 is poured into the ground where the soil is contaminated. The method for improving contaminated soil according to any one of claims 1 to 3, wherein the water that has entered the cylinder containing the adsorbent is pumped up.

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