JP4019069B2 - Method for accelerating disassembly of underground pipe, ground treatment and investigation method - Google Patents

Description

  The present invention is buried in the ground where microorganisms hardly exist, such as an injection pipe formed of biodegradable plastics after the purpose of ground injection, a soil purification pipe, or a research pipe for water quality investigation. In particular, a method for rapid degradation of civil engineering soils, in particular, after injection or investigation, if pipes are left in the ground and left buried, they are rapidly degraded by underground microorganisms, Disassembly of underground pipes that become harmless substances such as carbon dioxide gas and reduce the workability even when excavating the ground, such as sewage construction and shield construction, or do not worry about the components leaching into the groundwater It relates to the promotion method.

  In order to strengthen the ground by injecting an injection material into the ground, it is conventionally known to use a strainer injection tube device, a double tube double packer injection tube device, an injection tube device in which a plurality of injection thin tubes are bundled. ing.

  In addition, survey pipes have been buried to collect groundwater, inject water into the ground, or to test the submergence of soil layers, drainage drains have been installed, and recently, purification materials and air for soil purification have been installed. And the like are injected into contaminated water such as polluted soil, rivers, and swamps to purify them.

  These injection tubes and survey tubes were made of materials such as vinyl chloride, polyethylene, and polypropylene that have high tensile strength and are not degraded by living organisms. Alternatively, even if some parts are made of biodegradable plastic soot, and injection material, purification material, air, etc. are injected into the ground, the injection pipe device is left in the ground or in the water and buried, but the microorganisms in the ground A method has been developed and patented to convert it into harmless substances such as water and carbon dioxide gas. (Patent No. 3406567)

  In addition, as a biodegradation accelerator and biodegradation method for organic substances contained in various types of waste such as industrial waste, household waste, general waste, and the like, conventionally, a biodegradation accelerator containing a polyamino acid as an active ingredient and the same are included. Biodegradation methods are known. (Japanese Patent Laid-Open No. 2001-270793)

  However, the above-mentioned publicly known technologies are various types of waste such as paper waste, wood waste, pulp, cotton, wool and other industrial waste, waste food, household waste such as garbage, animal waste and animal waste, etc. The waste is decomposed in a garbage disposal facility such as a composting facility, and the target is markedly different from the treatment of buried injection pipes.

In general, many microorganisms are present in the soil, which is within about 1 m from the surface of the earth and has a lot of organic matter derived from plants. However, civil engineering pipes such as injection pipes, survey wells, and soil purification pipes are in the soil where there is almost no organic matter, and may reach a depth of 5 to 10 m or more. For this reason, under such conditions, even if biodegradable plastics are used, there is little survival of microorganisms that work effectively for degradation, and even if buried for many years, it is difficult to be degraded.
Japanese Patent No. 3406567 JP 2001-270793 A

  Therefore, an object of the present invention is to provide underground pipes such as injection pipes, survey wells, soil purification pipes, and water supply pipes in the soil, which are formed of biodegradable plastics that are buried in the ground where almost no microorganisms exist. After the purpose of use is reached, the material in which microorganisms are the active ingredient is injected into the soil buried pipes or filled in the soil, and then rapidly decomposed to improve the above-mentioned disadvantages of the known technology. It is an object to obtain a method for promoting the decomposition of buried pipes.

  In order to achieve the above-described problems, according to the present invention, an injection tube, a survey well tube, or a survey well formed entirely or partially after being used for use buried in the soil, is formed of biodegradable plastics. Inject or fill with compost containing soil microorganisms, soil, compost components, dredged soil, sludge, anaerobic bacteria such as Lactobacillus, and other materials containing microorganisms, or It is characterized by injecting or filling a dispersion liquid as an active ingredient.

  The present invention achieves the purpose of use in biodegradable underground buried pipes such as injection pipes, soil purification pipes, groundwater observation pipes, etc. buried deep in the ground where there are almost no microorganisms, and then the microorganisms exist. Since compost, soil, compost components, dredged soil, and a dispersion liquid containing microorganisms are injected or filled, the underground pipe is rapidly decomposed at the position in the ground. For this reason, it is not necessary to dig up or pull out underground pipes deeply buried in the soil and treat them as industrial waste, and they are decomposed at the same position in the ground.

Hereinafter, the present invention will be described in detail.
Underground pipes buried in the ground are used for injecting ground consolidation materials, injecting purification materials for contamination purification, introducing air for aeration, etc. Used as an observation well for.

  In order to achieve the purpose of injection of the above-mentioned underground pipes by injecting ground consolidation material or by injecting a soil purification agent, and further by conducting groundwater surveys to achieve the purpose, and then for underground use, Alternatively, it is desirable to remove these underground pipes in order to preserve the natural environment. However, in reality, it is almost impossible to remove these buried pipes because they must be dug deep underground. Furthermore, in the ground into which the ground consolidation material has been injected, the injection pipe is fixed to the ground by the consolidation material, and it is difficult to pull out.

  The present invention was developed from this point of view. Microorganisms injected or filled in underground underground pipes adhere to biodegradable plastics and polymer polymers are converted by hydrolytic enzymes of the microorganisms. The bound chain (ester bond) is cut, resulting in a low molecular weight degradation product that is taken up by microorganisms. (Primary decomposition)

  The incorporated decomposition products are further decomposed in microorganisms, and some (10-15%) become living organisms such as microorganism nutrients, and most (85.90%) become water and carbon dioxide. Discharged. (Secondary decomposition)

  The biodegradable plastic used in the present invention is a polymer compound that is decomposed by microorganisms, preferably thermoplastic, and can be processed by conventionally known extrusion molding and has mechanical strength as an injection tube. preferable. 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 promote 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. As these biodegradable plastics, specifically, as an example of the above (1), “Pionore” (aliphatic polyester of polyol and dicarboxylic acid) (Showa Polymer Co., Ltd. and Showa Denko Co., Ltd.), “ Examples of “Cell Green” (cellulose acetate, polycaprolactone) (Daicel Chemical Industries, Ltd.), “Lacty (lactic acid)” (Shimadzu Corporation), (2) “Poval” (polyvinyl alcohol) (stock) Examples of (Kuraray), (3) include “Wonder Stern” (corn starch and polyethylene) (Wonder Corporation) and the like.

  By blending the biodegradable plastics with high melting point biodegradable plastics such as polyhydroxybutyrate, 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.

  In addition, since biodegradable plastics is a surface reaction of the molded product and the enzyme metabolized from the body of microorganisms, the thicker the molded product, the longer the degradation time. On the other hand, when the injection 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 osmosis | permeation, and also changes greatly also by injection | pouring of an injection material. Therefore, the decomposition rate of the injection pipe cannot be generally determined, but when it is not excavated, it can be said that one year is a sufficiently short period. In addition, when excavating after injection, it is preferable to use biodegradable plastics that are more brittle.

  The biodegradable plastics according to the present invention can be decomposed or reduced in strength by lowering the weather resistance as necessary. Especially when such an injection tube apparatus is used, an injection operation is performed. Considering the previous management, it is preferable to avoid exposure to direct sunlight for a long time or leaving it in the rain as much as possible.

  A biodegradable plastic injection tube made of lactic acid polymer or aliphatic polyester is used because of its strength and heat resistance. Table 1 compares the properties of conventional plastics and biodegradable plastics.

  As the material to be injected or filled into the biodegradable plastic tube after the purpose of use used in the present invention is reached, fermentation compost containing a large amount of microorganisms such as bacteria and filamentous fungi that decompose organic matter is used. As fermentation compost, a soil in which a material containing a large amount of microorganisms such as humus and chicken manure is mixed and microorganisms are sufficiently cultured at high humidity is used. In addition, by injecting a dispersion containing microorganisms mixed with compost and having fluidity into the soil near the injection ground after injecting the ground consolidation material, not only in the injection pipe but also in the injection pipe Degradation can be further promoted by creating an environment that is easy to biodegrade on the outside. In addition to filling, it may be filled by pushing into the tube. Moreover, it is preferable to send air into the pipe from time to time so that microorganisms can be easily biodegraded.

  There are more than 10 trillion microorganisms in general soil, including fungi, bacteria, fungi, algae, protozoa, algae, etc. Among them, microorganisms that work effectively on biodegradable plastics include sugar, Cellulolytic bacteria having enzymes that hydrolyze aliphatic and lactic acid ether bonds and ester bonds are particularly effective.

  As microorganisms activated in the ground, fermentative bacteria and spoilage bacteria that are facultative anaerobic bacteria that do not need to send air by explosion or agitation can be used. In particular, yeast and lactic acid bacteria do not produce toxic substances such as ammonia and methane, and have the function of accelerating the decomposition of biodegradable plastics by using organic substances in compost to be injected at the same time.

  In particular, all anaerobic bacteria such as Lactobacillus (lactic acid bacteria) are non-spore anaerobic bacteria that produce alcohol and organic acids without consuming oxygen. Aerobic basidiomycetes and filamentous fungi rot the soil plants in the soil about 1-10 cm from the ground surface. The Lactobacillus group is distributed in the surface layer, the middle layer, and the lower layer. Therefore, even if the biodegradable plastic burial pipe is buried in the underground 5-10m or deeper than there is almost no air, it can be buried by injecting or filling these anaerobic bacteria. The tube is easily disassembled. Specific examples of the above-mentioned bacteria include plant organic matter fermented with Lactobacillus (oil cake, rice bran), animal organic matter, soil, sludge, compost, etc., plant fiber that has been corroded, or fermented. used.

  In the present invention, the underground pipe includes an underwater pipe. Moreover, the underground pipe | tube used for this invention does not necessarily need to be a cross-sectional circular shape, and includes things of arbitrary shapes, such as square shape.

  The biodegradable plastic tube used in the present invention is also used for soil purification. For example, an injection pipe is inserted into the ground contaminated with hexavalent chromium, and a reducing agent such as iron oxide is injected through the injection pipe to detoxify it, or groundwater contaminated with harmful organic substances is inserted into the ground. It sucks out to the ground through a water absorption pipe and makes it harmless. In addition, a plurality of pipes are buried in the ground, and a soil purification agent is injected from one buried pipe to make the pollutant harmless, while the other buried pipe absorbs groundwater and is contained in the groundwater. Measure the concentration and confirm the purification effect.

  After using the biodegradable plastic made of the above-mentioned buried pipe and conducting soil purification as described above, the buried pipe is filled with a material containing as an active ingredient a microorganism that decomposes the biodegradable plastics. By injecting or injecting, the buried pipe is disassembled in the ground and in a short time in its original position. As a result, both pollutants and buried pipes disappear, and the original ground is restored. In addition, there is no need to dig up used underground pipes and treat them as industrial waste.

  The biodegradable plastic pipe used in the present invention is also used for groundwater investigation. Conventionally, as groundwater surveys, when injecting ground to strengthen the ground, observation wells with buried pipes were set up in the surrounding ground, and water was collected from here to check for changes in groundwater. In the present invention, the buried pipe is replaced with a biodegradable plastic pipe, and after the observation is completed, a material containing microorganisms as an active ingredient is filled or injected into the buried pipe to decompose and extinguish the buried pipe.

  Furthermore, the biodegradable plastic pipe used in the present invention is also used for dehydration (drainage) in the ground. For example, by pressing inset ground grout, plastic grout, slump-free mortar, sand, etc. into soft ground, pushing the earth around and increasing the density of the earth, or by condensing the clay The ground has been improved. Permeation pipes are buried between these press-fitting areas, and groundwater whose pore pressure has increased by press-fitting is dehydrated to promote ground improvement. At this time, using the biodegradable plastic pipe of the present invention as a dehydrating pipe (drainage pipe), after dehydration proceeds, the dehydrating pipe is filled with microorganism-containing earth and sand, so that the dehydrating pipe is decomposed and extinguished. The function will disappear, and the soil will be improved to the same soil quality as the surrounding ground. Thereby, after the ground improvement, the land subsidence due to dehydration will not continue. In addition, when installing a buried pipe in the ground, water-permeable sand and a microorganism-containing material can be mixed and filled from the beginning. Depending on the material of the buried pipe, the thickness, and the type of microorganism, a period for decomposing the buried pipe can be assumed in advance. For this reason, the period in which the dehydration effect is required and the period in which the buried pipe is decomposed and extinguished can be returned to the normal ground.

  Furthermore, the biodegradable plastic pipe used in the present invention is used for the water permeable pipe (or drain material), which is buried in a soft ground, and after the ground improvement by the compaction effect, the water permeable pipe (or By filling or injecting a material containing microorganisms as an active ingredient into the drain material), the water permeable tube (or drain material) is decomposed and extinguished. At this time, if soil and sand etc. are filled with microorganisms, the soil will eventually have almost the same soil quality as the surrounding ground, and ground subsidence due to the drainage effect will never occur.

The results of the burying test of the injection tube made of vinyl chloride, a mixture of paper and lactic acid polymer, and an aliphatic polymer are shown below.
Since it is buried in the ground 1 to 10m, it is assumed that soil where a lot of microorganisms live near the surface (i) It is buried in agricultural compost, and soil that contains a lot of sand 5m deep below the ground (b) Toyoura standard sand (C) It is embedded in the Toyoura standard sand, and it is assumed that the material containing a lot of microorganisms is injected or filled in the soil. A tube filled with agricultural compost, and the above three conditions.

  As an injection tube, for comparison, a conventional injection tube made of vinyl chloride, an underground tube of the present invention, an injection tube made of a mixture of paper and lactic acid polymer as a biodegradable plastics tube and aliphatic polyester are used. A total of 3 points were prepared, 2 for the injection tube as the material.

1. sample
(1) Injection tube made of vinyl chloride
(2) Injection tube made of a mixture of paper and lactic acid polymer (biodegradable plastic tube)
(3) Injection tube made of aliphatic polyester (biodegradable plastic tube)

2. Sample size A sample having a length of 500 mm, an outer diameter of 50 mm, and a tube thickness of 2.5 mm. (Injection tube)

3. Test conditions (a) Buried in agricultural compost (b) Buried in Toyoura standard sand
(C) Agricultural compost filled in pipes is buried in Toyoura standard sand Embedding conditions: constant 58 ° C, moisture content 60%, dark place, stationary Embedding period: about 120 days

4). Experimental results Based on the experimental results, it was assumed that the sand of the present invention was deeper than 5m deep and the injecting material containing a lot of microorganisms was injected into the soil. Under the conditions, both the injection tube made of a mixture of paper and lactic acid polymer, and the injection tube made of an aliphatic polyester material collapsed when force was applied in 84 to 119 days, or the decomposition progressed until the shape disappeared . The experimental results are shown in Table 2.

From the experimental results of (a), it can be seen that the conventional injection tube has almost no change even during agricultural compost. On the other hand, it can be seen that the biodegradable plastic tube is readily decomposed in a short period of time.

The results of (b) show that biodegradable plastics decompose very slowly in Toyoura standard sand.

From the experimental results of (c), it was found that when a material containing compost containing microorganisms was injected or filled into a biodegradable plastic tube, the decomposition proceeded rapidly even in soil with almost no microorganisms.

According to the method for promoting the decomposition of underground pipes according to the present invention,
1. Since buried pipes such as injection pipes, survey pipes, soil purification pipes, drain pipes, etc. reach their purpose, they are decomposed in the soil and returned to their original state in a short period of time, so there is little impact on the environment.
2. Since the decomposition of the injection pipe is promoted by microorganisms, the injection pipe does not impair the workability in the subsequent construction such as underground excavation.
The industrial applicability is great.

Claims (7)

Buried biodegradable plastic pipe in the ground, on the ground during buried pipe after achieving the purpose, microorganisms become filled or injected material comprising as an active ingredient, whereby said underground pipe underground A method for promoting the decomposition of underground pipes , characterized in that the decomposition is promoted at the same position. According to claim 1, compost material as an active ingredient the microorganism containing microorganisms, soil, compost, clay, sludge and accelerated degradation of underground pipe according to claim 1 selected from the group of these dispersions Method.   The method according to claim 1, wherein the material containing microorganisms as an active ingredient contains anaerobic bacteria as an active ingredient. A ground treatment method for improving a ground by injecting an injection material through a underground pipe buried in the ground , wherein the underground pipe is a biodegradable plastic pipe, and is inserted into the ground through the underground pipe. after the grout injection, becomes a material containing, as an active ingredient, a microorganism is filled or injected into the underground pipe, thereby characterized in that said underground pipe is accelerated degradation in situ of underground Ground treatment method using underground pipes.   5. The ground treatment method according to claim 4, wherein the injection material is a ground consolidation material, a ground purification material, or air. In the underground survey method for investigating the ground or groundwater through the underground pipe buried in the ground , the underground pipe is a biodegradable plastic pipe , and after conducting the investigation, a material containing microorganisms as an active ingredient is used. underground searching method in the now filled or injected into the underground pipe, thereby characterized in that said underground pipe is accelerated degradation in situ of underground. In a ground treatment method for purifying the ground through underground pipes buried in the ground or investigating groundwater, the underground pipe is a biodegradable plastic pipe, and a soil purification agent is injected through the underground pipe. Alternatively, after the groundwater is sucked up to investigate the quality of the groundwater, the underground pipe is filled or injected with a material containing microorganisms as an active ingredient, so that the underground pipe is left in the ground. The ground treatment method is characterized in that decomposition is promoted at the position of.