JP2007111599A - Method for cleaning contaminated ground - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for cleaning a contaminated ground is characterized by using a biodegradable underground pipe upon cleaning a contaminated ground to be left buried permanently allowing it to decompose by virtue of microbes in the ground into harmless substances such as carbon dioxide so as not to hinder future ground excavation, which makes it possible to use the ground effectively. <P>SOLUTION: The method for cleaning a contaminated ground is characterized by comprising a step of burying a plurality of underground pipes 2 made from a biodegradable plastic in a contaminated ground, a step of cleaning the contaminated ground through the plurality of the underground pipes 2 using a specific grouting apparatus A and a subsequent step of permanently leaving the buried underground pipes 2 as they are to allow them to be decomposed by microbes in the ground to restore the once contaminated ground to an environmentally clean and natural state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention embeds a plurality of underground buried pipes which are microbially decomposed in the contaminated ground, and injects the purification material into the ground using the ground injecting apparatus equipped with one or a plurality of pumps. In particular, after the purification treatment, the buried pipes are decomposed by microorganisms in the soil by burying these underground pipes in the contaminated ground. It becomes a harmless substance such as carbon dioxide gas, and even when excavating the ground like the shield method, it can be used as a purification method for contaminated ground without worrying about reducing workability or eluting decomposition components into groundwater. In particular, the present invention relates to a method for purifying contaminated ground that can be used for land use by remnants such as injection pipes disappearing from the soil after soil purification and restoring the ground to a natural state.

  In recent years, the ground is at risk of contamination due to various causes. Conventionally, various methods are known as a purification technique for contaminated ground. For example, as a “containment technology”, a technology that solidifies the pollutant by injecting cement or other solidified material into the contaminated ground, or a chemical material such as a metal sequestering agent or reactive agent in the contaminated ground is contaminated. Techniques for insolubilizing substances are known. Furthermore, as a “purification technology”, a technology is known in which contaminated soil or groundwater is extracted, purified by chemical decomposition or biodegradation, and the purified soil or groundwater is injected into the ground.

  In the above-mentioned "containment technology" and "purification technology", tensile strength such as vinyl chloride, polyethylene, polyprolene, etc. is used when injecting caking materials and chemicals into the contaminated ground, or extracting and injecting contaminated soil and contaminated groundwater. An injection tube made of a material that is large and is not decomposed by microorganisms is used.

  In addition, in order to test and collect groundwater, or to test the submergence of soil layers, survey pipes are buried underground, drainage drain pipes are installed underground, etc. ing. These survey tubes and drain tubes are also made of a material having a high tensile strength and not decomposed by microorganisms, as described above.

  In many cases, the injection tube, the survey tube, or the drain tube used in the above-mentioned “containment technology” and “purification technology” are usually left in the ground. However, when excavating the ground after purification, or excavating the ground as in the shield method, the remaining buried pipe becomes an obstacle and the workability is reduced, or its components from the plastics of the above pipe material Elution will cause harmful effects such as contaminating groundwater. Therefore, there is a demand for a technology that can be used in the natural state after soil purification.

  In recent years, all or part of the injection tube that is decomposed by microorganisms is made of biodegradable plastics, and after injecting the injection material into the ground to improve the ground, the injection tube is left behind in the ground and buried. A ground injection method for decomposing by underground microorganisms has been filed and patented by the present applicant (Japanese Patent No. 3406567). In addition, a method for injecting an injection material into the ground to fix and detoxify harmful substances in the ground has been filed and patented by the present applicant (Japanese Patent No. 3455952).

However, in the former patent, when the injection material is injected into the ground, it is a technique using an injection tube that is decomposed by microorganisms, and the present invention further develops this technique, and after purifying the contaminated ground, It was restored to the land as it was and made possible to use the land afterwards.
Japanese Patent No. 3406567 Japanese Patent No. 3455952

  The problem to be solved by the present invention is that one or a plurality of pumps are provided for burying underground buried pipes that are decomposed by microorganisms in the contaminated ground, and performing purification treatment of ground pollution through the buried pipes. Injecting the purification material into the ground using a ground injection device, and purifying the soil contamination, in particular, after the purification treatment, the buried pipe is buried in the soil by burying it in the ground. It is decomposed by microorganisms and becomes harmless substances such as carbon dioxide, and after that, excavating the ground to build a building, or even when excavating the ground like the shield method, the workability is reduced, It is an object of the present invention to provide a method for purifying contaminated ground, which makes it possible to effectively use land without worrying about elution of decomposition components into groundwater, and which improves the above-described drawbacks of the known technology.

  In order to solve the above-described problem, according to the method of the present invention, a plurality of underground pipes made of biodegradable plastics are embedded in a contaminated ground, and the ground is passed through the plurality of underground pipes. Using a pouring device, a purification material is injected into the ground to purify the soil contamination, and then the plurality of underground pipes are buried in the ground as they are and decomposed with soil microorganisms, It is characterized in that it can be restored to a natural ground so that it can be used for the subsequent effective use of the land, and the ground injection device comprises the following (A) or (B).

(A) A pressurizing unit that pressurizes the purifying material to a predetermined pressure with a single pump, a conduit that communicates with the pressurizing unit and sends the purifying material to the underground pipe, and a throttle provided in the conduit The purification material is injected into the ground with a single pump through the plurality of underground pipes.

(B) A multi-injection apparatus having a large number of unit pumps each operated by an independent drive source and controlled by a centralized control device, each of which is buried in a plurality of soils through a conduit. A plurality of unit pumps are connected to the pipe, and a plurality of unit pumps are operated to simultaneously inject the purification material from a plurality of underground pipes through a plurality of injection points in the ground.

  The present invention uses a soil buried pipe that is decomposed by microorganisms in performing a soil contamination purification treatment, and in particular, after the purification treatment, the soil buried pipe is buried in the ground. When buried pipes are decomposed by microorganisms in the soil and become harmless substances such as carbon dioxide gas, workability is reduced even when excavating the ground to construct buildings or excavating the ground like the shield method. And there is no worry of eluting decomposition components into groundwater.

  Further, in the present invention, in performing the soil contamination purification treatment, a plurality of underground pipes that are decomposed by microorganisms are embedded in the soil, and one or a plurality of pumps are provided through the underground pipes. By injecting the purification material into the ground using the ground injection device, the injection can be performed quickly and a plurality of injection regions can be performed simultaneously.

Hereinafter, the present invention will be described in detail.
In the present invention, a plurality of underground pipes are buried in a contaminated ground from biodegradable plastics, and a purification material is injected into the ground using the ground injection apparatus through the plurality of underground pipes. Then, the soil contamination is purified.

  The above-mentioned biodegradable plastics are high molecular compounds that are decomposed by microorganisms, and are preferably thermoplastic. The underground pipe according to the present invention is made of this biodegradable plastic material and is molded to have mechanical strength as an injection pipe by a conventionally known extrusion molding or the like. Water-soluble plastics, particularly plastics that dissolve under alkaline conditions, are easily decomposed by living organisms and are preferred in the present invention.

  The chemical structure is (1) the main chain is aliphatic and has an ether bond or ester bond, (2) the main chain (or side chain) has a hydroxyl group or a carboxyl group, or (3) plastic. It is a plastic with good biodegradability by containing additives that induce and accelerate photodegradation and microbial degradation of starch, specifically starch-based, cellulose acetate-based, polylactic acid-based, aliphatic polyester-based, Examples thereof include biodegradable plastics such as polyvinyl alcohol. To these main raw materials, other polymer compounds such as plastics such as polyethylene and polypropylene, plasticizers, stabilizers, colorants and the like are added as necessary for the purpose of improving performance or imparting flexibility. You can also

  The compound (2) having a hydroxyl group or a carboxyl group is preferably an aliphatic compound. Specific examples of these biodegradable plastics include “Pionore” (aliphatic polyester of polyol and dicarboxylic acid) (Showa Polymer Co., Ltd. and Showa Denko Co., Ltd.), “Cell” Examples of “green” (cellulose acetate, polycaprolactone) (Daicel Chemical Industries, Ltd.), “lacty (lactic acid)” (Shimadzu Corporation), (2), “Poval” (polyvinyl alcohol) (Ltd.) Examples of (Kuraray) and (3) include “Wonder Starken” (corn starch and polyethylene) (Wonder Corporation), and the like.

  By blending the above biodegradable plastics with high melting point biodegradable plastics such as polyhydroxypropylate, polylactic acid, polyglycoside, etc., the processability is improved, and a woven fabric or non-woven fabric is used as a bag. Can also be used. These main raw materials are decomposed in the soil by bacteria for, for example, about 90 to 300 days.

  Biodegradable plastics is a surface reaction between the molded product and an enzyme that is metabolized from the body of the microorganism. Therefore, the thicker the molded product, the longer the degradation time. On the other hand, when the purification material is alkaline, biodegradable plastics having an ester bond are susceptible to hydrolysis. Moreover, the injection | pouring ground exists in various different conditions, such as acidic to alkaline or seawater penetration, and also changes with injection | pouring of injection | pouring materials. Therefore, the decomposition rate of the injection pipe cannot be generally determined, but when it is not excavated, it can be said that it is sufficiently short even for one year. Also, when drilling after injection, it is preferable to use more brittle biodegradable plastics.

  The biodegradable plastics according to the present invention can be decomposed or reduced in strength by reducing the weather resistance as required. When such an injection tube is used, particularly before the injection operation. For example, it is preferable to avoid exposure to direct sunlight for a long time or leaving it in the rain as much as possible. As biodegradable plastics, lactic acid polymers and aliphatic polyesters are used as materials in terms of strength and heat resistance. The properties of the conventional plastics and the biodegradable plastics of the present invention were compared, and the results are shown in Table 1.

  Furthermore, the present invention contains cellulose fibers in the above-described biodegradable plastics to reduce the elongation rate, and makes the resin easy to be crushed without being stretched even when external pressure is applied, and this resin is used as a raw material by extrusion molding or injection molding. Underground pipes can also be formed.

  Examples of the cellulose fiber used in the present invention include fibers obtained by defusing plant fibers such as waste paper, wood flour, hemp, cotton pulp, and wood pulp. In the present invention, such cellulose fibers are kneaded and granulated in biodegradable plastics at a moisture content of 5 to 40%. Alternatively, the cellulose fiber is kneaded with biodegradable plastics in the presence of water whose moisture content of the cellulose fiber does not cut the lower limit of 5%, and the obtained kneaded product is in the range of 5 to 40% of the moisture content of the cellulose fiber. Granulate.

  In the present invention, when cellulose fibers are used, it is important to fully consider the behavior of cellulose fibers during pellet production. Cellulose is a typical hydrophilic polymer substance that absorbs and desorbs moisture very much, and its properties change depending on the state of moisture absorption and desorption. That is, it swells and softens due to moisture absorption and becomes flexible and easily deformed, while it becomes keratinized and hardened by dehumidification, becomes brittle and difficult to deform.

  The reinforcing fiber used in the present invention is a vegetable fiber as described above, and after defibration or immediately after, it is subjected to strong shearing in biodegradable plastics in a molten or softened state at around 100 ° C. or higher. Knead uniformly while applying force. Under these conditions, the plant fiber mainly composed of cellulose loses moisture and becomes completely dry, so it becomes keratinized, hard and brittle. Therefore, when kneaded by applying a strong shearing force in this absolutely dry state, the cellulose fibers are pulverized until they are uniformly dispersed in the biodegradable plastics and do not remain in the fibrous form.

  This tendency is more conspicuous as in the case of biodegradable plastics having a high melting temperature or softening temperature, and not only the fibers deteriorate during pulverization and become powdery, but also the thermal deterioration further progresses, leading to carbonization. May be affected. In order to avoid this state, the underground buried pipe of the present invention is formed by injection molding or extrusion molding of a biodegradable plastic with a reinforcing fiber added thereto using a mold. Table 1 shows a comparison of properties between the conventional injection tube material and the injection tube material of the present invention, that is, biodegradable plastics to which reinforcing fibers are added.

  In the present invention, the plurality of underground pipes are then buried in the ground as they are, and then decomposed with microorganisms in the ground, so that the contaminated ground can be restored to the natural ground and used for subsequent effective use of the land. It is characterized by. In the present invention, the underground pipe may be a survey pipe for surveying geology and groundwater.

The above-described soil contamination purification process is performed by any one of the following (a) to (f) or a combination of these.
(A) A caking material is injected into the ground through a buried pipe in the soil to solidify the pollutants in the soil.
(B) Insolubilizing agent is injected into the ground through the underground pipe.
(C) Extract the contaminated water from the contaminated ground through the underground pipe, wash it, and inject it into the ground again.
(D) A chemical substance that causes a catalyst purification reaction or a chemical substance that causes bioremediation is injected into the contaminated ground through the underground pipe and purified.
(E) Water is poured into the contaminated ground through underground pipes, washed and purified.
(F) Air is injected into the contaminated ground through the underground pipe and the pollutants are decomposed by aeration.

  The above-mentioned ground contamination treatment of the present invention is performed using the following ground injection device (A) or (B).

Ground injection device (A)
A pressurizing unit that pressurizes the purifying material to a predetermined pressure with a single pump, a conduit that communicates with the pressurizing unit and sends the purifying material to the underground pipe, and a throttling portion provided in the conduit Thus, the purification material is injected into the ground with a single pump through the plurality of underground pipes. Specifically, for example, the apparatus shown in FIG.

  In detail, as shown in FIG. 1, the ground injection device A of the present invention includes a plurality of injection pipes (underground pipes) 2, 2,... In which the purification material 5 is installed in the ground 3. 2 is a device for injecting into the ground 3 through a pressurizing unit 1 that pressurizes the purifying material 5 to a predetermined pressure, and communicates with the pressurizing unit 1 to send the purifying material 5 to the injection conduit 2. It is basically composed of a conduit 6 and a throttle portion 7 provided in the conduit 6. In addition, you may provide the throttle part 7 in the upper end part of the conduit | pipe 6, ie, the branch point of the liquid feeding system 13 and the conduit | pipe 6, or the exit from the distribution apparatus 11 mentioned later to the conduit | pipe 6.

In addition, as shown in FIG. 1, the return system RS of the purification material, that is, the liquid flow meter f ₀ and / or the liquid pressure gauge P ₀ , is supplied to the liquid supply system 13 that reaches the throttle portion 7 of the purification material 5. A return device RA is provided, and the return device RA is controlled by the flow rate pressure control device 10 so as to maintain a predetermined injection pressure P _0, and a part of the purification material is returned to the purification material tank 4 through the return line R. That is, in the return system RS, the flow rate pressure control device 10 receives signal information from the liquid feeding pressure gauge P ₀ and / or the liquid feeding flow meter f ₀ , and transmits this signal to the return device RA. The return device RA diverts the purifying material in the liquid feeding system 13 from the liquid feeding system 13 to the return line R based on information from the liquid feeding pressure gauge P ₀ and / or the liquid feeding flow meter f ₀ , and a purifier tank. 4, the liquid pressure of the liquid feeding system 13 is maintained at a desired pressure, and thereby, the discharge amount of the purifying material fed from the conduit 6 to the injection conduit 2 through the throttle portion 7 is maintained at a predetermined amount. To do.

In FIG. 1, the purification material 5 is injected from a high pressure portion on the upstream side of the throttle portion 7 to a low pressure portion on the downstream side. In this case, if the pressure difference between the injection pressure P _{0 of the} pressurized purification material 5 and the injection pressure P _1n of the ground 3 to be injected is sufficiently large, the respective conduits 6, 6. Even if the injection pressures of 6 vary, the discharge amount (injection speed) of each conduit 6 is almost the same if the area of the throttle portion 7 is the same. Then, the discharge amount is determined by the area of the holes of the injection pressure P ₀ and the throttle portion 7.

  However, in FIG. 1, the purifier 5 is not always injected from all the conduits 6, 6... 6 exactly in the same way from the beginning to the end of the injection, or it is completed early depending on the target injection point. The conduit 6 that ends the process also comes out. However, when a part of the conduits 6, 6... 6 finishes the injection, the injection amount is distributed to the remaining other conduits 6, 6. The discharge amount from the remaining conduits 6, 6... 6 increases. In order to prevent this, an inverter (not shown) of the pump 14 is adjusted to adjust the rotation speed, and the pressure is dropped to adjust the flow rate or the return system is operated. In this way, the pressure of the liquid supply system 13 can be maintained at a predetermined value regardless of the fluctuation of the number during the injection of the conduit 6, and the injection of a predetermined flow rate from each conduit 6, 6,... Can continue to.

Further, in FIG. 1, from the start to the end of injection, the return system RS sets the injection pressure P ₀ to an arbitrary value to automatically return the purifying material 5, and the injection pressure P ₀ and the operating conduit 6 , 6... 6 can be arbitrarily obtained. Furthermore, by providing an inverter (not shown) in the pump 14, it is possible to adjust to a predetermined flow rate or pressure within the most appropriate flow rate range (pressure range). Thus, in the present invention, the pressurizing unit 1 that pressurizes the ground injection liquid to a predetermined pressure by the return system RS, the inverter, or a combination thereof is referred to as a pressurizing unit 1 having a flow rate pressure control function. In FIG. 1, a distributor 11 may be provided between the liquid feeding system 13 and the conduit 6, and the conduits 6, 6... 6 may be extended from the distributor 11. Reference numeral 12 denotes a connecting portion between the conduit 6 and the injection conduit 2. Further, as shown in FIG. 1, the conduit 6 has branch valves V ₁ , V ₂ ... V ₁ , V _n , a pressure gauge (pressure detector) 8, and a flow meter (flow rate detector) 9. It can also be provided arbitrarily.

Ground injection device (B)
A multi-unit injection device (multi-point ground injection device) that is operated by an independent drive source and is controlled by a centralized control device. By connecting a plurality of unit pumps, the purification material is simultaneously injected at a plurality of points through a plurality of injection points in the ground. Specifically, for example, the apparatus shown in FIG.

  More specifically, the ground injection device B in FIG. 2 is a multiple-injection injection device 15 that operates with the purification material tank 4 and independent drive sources 16, 16,... And a plurality of unit pumps 18, 18... 18 connected to and controlled by the central control device 17 and connected to the purifier tank 4 through the respective conduits 6, 6. A discharge port 20, which is embedded and arranged in an injection point 19 in the ground 15 with the device 15, each connected through a respective unit pump 18, 18... 18 and conduits 6, 6. A plurality of injection pipes (underground pipes) 2, 2.

  Further, the above-described independent unit pumps 18, 18,... 18 are provided with rotational speed transmissions 21, 21,. In addition, the conduits 6, 6... 6 connecting the unit pumps 18, 18... 18 and the injection pipes 2, 2. A flow pressure detector 22 is provided. For example, Y-shaped tube rods are used for the injection conduits 2, 2. 23 is a valve.

  With the above configuration, in the present invention, a flow rate / and / or pressure data signal from the flow pressure detector 22 is transmitted to the central control device 17, and the purification material in the purification material tank 4 is transferred to each unit pump 18, 18,. 18 is pumped to each injection pipe 2, 2... 2 at an arbitrary injection speed, injection pressure or injection volume by the operation of 18, and the injection point in the ground 3 from a plurality of discharge ports 20, 20. 19, 19... 19 are implanted at multiple points to form an implantation region 24.

  Examples of the unit pump 3 used in the present invention include a piston pump, a plunger pump, a diaphragm pump, a squeeze pump, and a snake pump. These pumps, except for the piston pump, are all small in size, simple in structure, and less likely to break down. Therefore, not only solution type but also suspension type grout can be used. Is suitable.

  In the purification treatment of soil contamination, by using underground pipes that are decomposed by microorganisms, in particular, after the purification treatment, the buried pipes are buried by burying them in the ground. It is decomposed by microorganisms in the soil and becomes a harmless substance such as carbon dioxide gas, and there is no worry of degrading workability and elution of decomposition components into groundwater when excavating the ground like the shield method. . Therefore, the construction method of the present invention has high applicability in the field of civil engineering and construction.

It is a flow sheet of one specific example of the ground injection device (A) used in the present invention. It is a flow sheet of one specific example of the ground injection device (B) used in the present invention.

Explanation of symbols

A Ground injection device B Ground injection device 1 Pressurization unit 2 Injection pipeline 3 Ground 4 Purification material tank 5 Purification material 6 Conduit 7 Throttle unit 8 Pressure gauge 9 Flow meter 10 Flow pressure control device 11 Distribution device 12 Connection unit 13 Liquid feeding System 14 Pump 15 Multiple injection device 16 Drive source 17 Centralized control device 18 Unit pump 19 Injection point 20 Discharge port 21 Rotational speed transmission 22 Flow rate pressure detector 23 Valve 24 Injection region

Claims (17)

A plurality of underground pipes made of biodegradable plastics are buried in the contaminated ground, and the purification material is injected into the ground using the ground injection device through the plurality of underground pipes. The soil contamination is then purified, and then the multiple underground pipes are buried in the ground as they are, and then decomposed with soil microorganisms. A method for purifying contaminated ground, characterized in that the ground injecting device comprises the following (A) or (B).
(A) A pressurizing unit that pressurizes the purifying material to a predetermined pressure with a single pump, a conduit that communicates with the pressurizing unit and sends the purifying material to the buried pipe, and a throttling portion provided in the conduit; The purification material is injected into the ground with a single pump through the plurality of underground pipes.
(B) A multi-injection apparatus having a large number of unit pumps each operated by an independent drive source and controlled by a centralized control device, each of which is buried in a plurality of soils through a conduit. A plurality of unit pumps are connected to the pipe, and a plurality of unit pumps are operated to simultaneously inject the purification material from a plurality of underground pipes through a plurality of injection points in the ground.   2. The method for purifying contaminated ground according to claim 1, wherein the buried pipe in soil is made of biodegradable plastics containing cellulose fibers to be easily pulverized resin, and the resin is used as a raw material.   The polluted ground purification according to claim 2, wherein the cellulose fiber is a fiber obtained by defibrating one or more kinds of plant fibers selected from the group of waste paper, wood flour, hemp, cotton pulp and wood pulp. Method.   The method for purifying contaminated ground according to claim 1, wherein the biodegradable plastics is a thermoplastic polymer compound that is decomposed by microorganisms.   2. The method for purifying contaminated ground according to claim 1, wherein the biodegradable plastics are plastics that dissolve under alkaline conditions. The underground pipe according to claim 1, wherein the biodegradable plastics is 1, 2 or 3 below.
(1) The main chain is aliphatic and has an ether bond or an ester bond.
(2) Those having a hydroxyl group or a carboxyl group in the main chain or side chain,
(3) Plastics with good biodegradability by containing additives that induce and promote photodegradation and microbial degradation of plastics, starch-based, cellulose acetate-based, polylactic acid-based, aliphatic polyester-based And biodegradable plastics selected from the group of polyvinyl alcohols. The method for purifying contaminated ground according to claim 1, wherein the purification treatment for ground contamination is any one or a combination of the following (a) to (f).
(A) A caking material is injected into the ground through a buried pipe in the soil to solidify the pollutants in the soil.
(B) Insolubilizing agent is injected into the ground through the underground pipe.
(C) Extract the contaminated water from the contaminated ground through the underground pipe, wash it, and inject it into the ground again.
(D) A chemical substance that causes a catalyst purification reaction or a chemical substance that causes bioremediation is injected into the contaminated ground through the underground pipe and purified.
(E) Water is poured into the contaminated ground through underground pipes, washed and purified.
(F) Air is injected into the contaminated ground through the underground pipe and the pollutants are decomposed by aeration.   The method for purifying contaminated ground according to claim 1, wherein the pressurizing unit of the ground injection device (A) comprises a return device and / or an inverter having a function of controlling the flow rate and pressure of the purifying material.   2. The pressure gauge and / or flow meter is further provided in the conduit downstream of the throttle portion of the ground injection device (A) according to claim 1, and the throttle portion is based on information from the pressure gauge and / or flow meter. The method for purifying contaminated ground according to claim 1, wherein the discharge amount and / or discharge pressure of the purifier sent from the conduit to the underground pipe is adjusted by adjusting the throttle.   The method for purifying contaminated ground according to claim 1, wherein the throttle portion of the ground injection device (A) is an orifice or a flow control valve having a flow area set to a predetermined value.   2. The throttle unit of the ground injection device (A) according to claim 1, comprising a reversible motor and a shaft that is connected to the reversible motor and interlocks vertically by operation of the motor, and the shaft is inserted into the conduit line from the tip. The method for purifying contaminated ground according to claim 1, wherein the restriction of the cross section of the conduit pipe is adjusted by being interlocked vertically.   2. The method for purifying contaminated ground according to claim 1, wherein each unit pump of the ground injection device (B) includes a rotational speed transmission controlled by a centralized management device.   2. The method for purifying contaminated ground according to claim 1, wherein the discharge ports of the plurality of underground pipes are installed at different injection points in a planar direction.   2. The method for purifying contaminated ground according to claim 1, wherein the discharge ports of the plurality of underground pipes are installed at different injection points in the depth direction.   In claim 1, flow rate pressure detectors are provided in the conduits that lead to the plurality of underground pipes, and the flow rate and / or pressure data signals of the purifiers detected from these detectors are transmitted to the central control device. 2. The method for purifying contaminated ground according to claim 1, wherein the purification material is injected at multiple points from the unit pumps to the plurality of injection points in the ground through the discharge ports of the plurality of underground pipes based on the information.   16. The unit pump according to claim 15, wherein each unit pump includes a rotation speed transmission controlled by a centralized management device having an injection monitoring panel, and operates the rotation speed transmission based on a data signal detected from a flow pressure detector. The method for purifying contaminated ground according to claim 15, wherein the purification material is fed to each underground pipe while maintaining a desired pressure and / or flow rate. In Claim 15, collective monitoring of the injection | pouring condition is performed by displaying on the injection | pouring monitoring board the signal of the flow volume and / or pressure data of the purification material which were detected from the said flow pressure detector, and each in an underground pipe | tube The method for purifying contaminated ground according to claim 15, wherein the injection is carried out while maintaining the injection pressure and / or flow rate within a predetermined range, and the completion, suspension, continuation or reinjection of injection is performed based on the information of the data.