JP3831235B2 - Soil packed column test system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a soil-filled column test system, and more particularly, can be carried out simply and efficiently using a continuous water-flowing soil-filled column, and bioremediation (treating of environment) and treatability of contaminated soil ( (Processability) The present invention relates to a soil-filled column test system that can increase the reliability of the survey.
[0002]
[Prior art]
Pollution prevention by heavy metals such as chromium, cadmium and lead has been screamed for a long time, but in recent years, industrial wastes such as halogenated hydrocarbons such as phenol, cyan and chlorofluorocarbons, or dioxin compounds generated during waste disposal Contamination of soil, runoff with rainwater, and mixing with drinking water has caused frequent problems such as causing health damage and psychological anxiety for local residents. The fundamental measure is to remove the contaminated soil and replace it with clean soil. However, this operation takes a lot of time, labor and cost.
[0003]
As an alternative, bioremediation methods such as spraying (injecting) microorganisms capable of degrading pollutants into contaminated soil have been studied and are considered promising. It is important to know beforehand the properties of the soil and microorganisms that inhabit it by column tests.
[0004]
The column test is carried out by reflecting the information obtained from site characterization (understanding the in-situ underground environment) and flask test, and acquiring the data (construction technology, cost, time, etc.) necessary for local construction design. The purpose is to do. Nutrient solution with conditions effective for restoration obtained by flask tests is continuously supplied to the soil-filled column that simulates the underground environment of the actual contaminated site at the underground flow rate assumed at the time of restoration. It is intended to collect activation data for pollutant-degrading bacteria, determine the construction method, and collect more reliable data on the cost and time required for restoration.
[0005]
Up to now, bioremediation technology has been actively developed in Japan for about 10 years, but it is said that there are many know-how elements in conducting column tests and the amount of information is extremely short. Currently.
[0006]
Japanese National Publication No. 10-503583 proposes a lysimeter for collecting a chemical component sample for monitoring moisture in the soil of a golf course, and Japanese Patent Application Laid-Open No. 10-225677 discloses an organic pollutant, particularly a halogenated fat. Compositions for bioremediation of soils and groundwater contaminated with aromatic compounds, halogenated aromatic compounds and methods therefor have been proposed.
[0007]
At present, as a column test, for example, a method using a column test apparatus as shown in FIG. 2 is common. A cylindrical soil-filled column 1 (hereinafter simply referred to as a column) is filled with target soil / sand so as to be the same as the contaminated land, and is installed in a standing state. A nutrient solution is supplied from the nutrient solution storage tank 11 to the column 1 by a pump 12. The nutrient solution ascends inside the column 1 and is partially consumed by microorganisms that inhabit the soil, and then discharged to the effluent tank 13.
[0008]
The nature of the soil is analyzed by extracting the effluent from the sampling port 15 ′ of the column 1. However, since the temperature of the apparatus members is not controlled in this test apparatus, when the target concentration for the column test is set, the microbial activity is uniformly increased not only inside the column but also in all the water supply paths, and the microorganisms outside the column Occurred and the water passage was blocked.
[0009]
The apparatus described in the above-mentioned Japanese translation of PCT publication No. 10-503583 is useful for sampling groundwater from soil, but cannot be modified or diverted to a column test apparatus to be implemented before bioremediation. Japanese Patent Application Laid-Open No. 10-225677 describes a method of stimulating microorganisms (indigenous bacteria) that reduce and degrade pollutants with nutrients, but there is no description about the column test.
[0010]
FIG. 4 shows the structure of a column conventionally employed. Since the column 1 has a single elongated tube structure that communicates in this way, in order to collect soil, the soil 2 inside the column is not scraped out at the stage of disassembling the device that has finished the column test. And the soil could not be evaluated. Therefore, the soil can be collected only once and there is a problem in evaluation, and it becomes necessary to scrape the soil deep in the column, and the operation is very complicated.
[0011]
Under such circumstances, there has been an urgent need for a continuous water-soil-type soil-filled column test system that is simple in structure, easy to operate, and accurate.
[0012]
[Problems to be solved by the invention]
In view of the above-mentioned problems, the present invention is a soil-filled column test system that can be implemented simply and efficiently using a continuous water flow column and can enhance the reliability of environmental repair and possibility investigation of contaminated soil. The purpose is to provide.
[0013]
[Means for Solving the Problems]
As a result of diligent research to achieve the above object, the inventors of the present invention approximated the soil temperature in the column of the continuous-flow soil-filled column test system as much as possible to the actual soil underground temperature, By storing the liquid storage tank and sampling effluent at a low temperature in a sealed state, it is possible to suppress the growth of various bacteria, and by adopting a column with a structure in which unit columns that can be connected and separated are stacked, The present inventors have found that a continuous water-soil-filled column test system having a simple structure, which is easy to operate, efficient and accurate can be obtained.
[0014]
That is, according to the first aspect of the present invention, a nutrient solution containing a nutrient necessary for activating the decomposing bacteria is applied to a soil packed column (A) filled with soil / sand mixed with degrading bacteria. The nutrient solution is continuously supplied in an upward flow from the stored storage tank (B), the effluent flowing out from the column (A) is sampled, and the activity of the decomposing bacteria is analyzed by analyzing the sampled effluent (C). A continuous water-flowing soil-filled column test system for determining the crystallization conditions, wherein the soil temperature in the column (A) is approximated as much as possible to the actual soil underground temperature by means of temperature atmosphere adjustment, while the storage tank (B) In addition, a continuous water-flowing soil-filled column test system is provided in which the sampling effluent (C) is stored at a low temperature in a sealed state in order to suppress the propagation of germs.
[0015]
According to a second aspect of the present invention, there is provided the continuous water-borne soil-filled column test system according to the first aspect, wherein all members constituting the system are coated or formed with a light-shielding substance. Provided.
[0016]
The third invention of the present invention is characterized in that, in the first invention, a nutrient solution pre-bubbled with an oxygen mixed gas is used in order to make the soil in the column (A) an aerobic environmental condition. A continuous water-based soil packed column test system is provided.
[0017]
According to a fourth aspect of the present invention, in the third aspect of the invention, the oxygen mixed gas is a mixture of air and inert gas mixed with a predetermined amount of oxygen. A column test system is provided.
[0018]
According to a fifth aspect of the present invention, in the first aspect, the column (A) is composed of a plurality of unit columns stacked in multiple stages, and has a configuration in which the nodes connected to each unit column are joined. In addition, there is provided a continuous water-flowing soil-filled column test system characterized by having a structure capable of extracting a portion of soil as a sample for evaluation by separating at a node portion.
[0019]
In addition, in a sixth aspect of the present invention, in the fifth aspect, instead of the extracted soil, a spacer having the same shape as the soil and having an internal filler that can be passed is extracted. A continuous water-flowing soil-filled column test system is provided, which is characterized in that the system is disposed in a void portion that has been born.
[0020]
Further, according to a seventh aspect of the present invention, in the first aspect, a pressure gauge or a differential pressure gauge is installed in the water supply pipe connecting the column (A) or the column (A) and the storage tank (B). A continuous water-based soil packed column test system is provided.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
1. Column Test System The column test system of the present invention approximates the soil temperature in the column to the actual soil underground temperature, and the nutrient solution storage tank and the sampling effluent are stored at a low temperature to suppress the propagation of various bacteria. This is characterized in that a continuous water-flowing soil-filled column test apparatus was constructed.
[0022]
That is, the system of the present invention includes a column filled with soil, a storage tank for nutrient solution, and a storage tank for sampling effluent, and the column is adjusted by the temperature atmosphere adjusting means so that the soil is close to the actual soil underground temperature. In addition, it is devised to maintain at a low temperature by placing at least a nutrient solution storage tank and a sampling effluent storage tank in which various bacteria propagate under normal temperature or higher conditions in a refrigerator.
[0023]
The column is filled with soil that mimics the soil to be evaluated. In general, soil is inhabited by a wide variety of microorganisms suitable for survival in the environment. Depending on the type of pollutants such as heavy metals, phenol, cyanide, chlorofluorocarbon and dioxin compounds, bioremediation is carried out to determine what kind of microorganism is preferable for decomposition and treatment and how much it should be present. This is an important judgment material.
[0024]
Taking a cyanide compound as an example of the pollutant, it is considered that microorganisms belonging to the genus Bacillus, Subtilis, Kubota, Fusarium oxysborum, Gordona or Burkholderia, which can decompose metal cyano complexes and the like, can be used.
[0025]
Naturally, the nutrient substance is appropriately selected according to the type of microorganism. For microorganisms that decompose cyanide, it seems desirable to contain glucose, fructose, galactose, saccharose, lactose, maltose, etc. as oxygen and carbon sources.
[0026]
These nutrients are dissolved in water and stored in a tank. The nutrient solution is introduced from the bottom of the column at a rate of 1 to 20 ml / hr, extracted in an upward flow, stored in a sampling effluent tank, and collected from an intermediate pipe and analyzed. The reason why the nutrient solution is made to flow upward is that in the downward flow, water is formed in the soil inside the column, causing experimental errors.
[0027]
It is desirable that all members constituting the system are made of a light shielding material. For plastic pipes such as Teflon (registered trademark), the outer surface may be covered with a sheet or the like. In fact, the place where bioremediation is applied is usually underground, and does not reach light. Therefore, if a photosynthetic microorganism (such as cyanobacteria) grows and the pollutant is decomposed, an analysis error is caused. However, if a light-shielding substance is used, the reproduction of the photosynthetic microorganism can be suppressed and an improvement in accuracy can be expected.
[0028]
If the nutrient solution is previously bubbled with an oxygen mixed gas, the soil inside the column can be brought into an aerobic environmental condition. In the oxygen mixed gas, oxygen is diluted with air or an inert gas, and the ratio thereof is adjusted and supplied to the nutrient solution storage tank. As a result, it has become possible to divide the oxygen concentration level step by step at a predetermined dissolved oxygen concentration level, which has conventionally been difficult in terms of hardware.
[0029]
2. The column column is composed of a plurality of unit columns stacked in multiple stages, and can be connected at this node portion and can be easily separated, so that one volume of soil can be extracted as a sample for evaluation. The inner diameter of the column 1 is preferably 10 to 30 mm, and the total length is 500 to 1500 mm (the length of the unit column is 150 to 200 mm). In addition, prepare a spacer having the same external shape as the shape of the soil to be extracted, and if the spacer with the internal filler that can be passed through is positioned in the void after extracting the soil, the test will continue to the end. can do.
[0030]
Since the object to be purified is soil, it is necessary to evaluate the soil in the column (calculation of basic physical properties such as soil packing density, porosity, hydraulic conductivity, or evaluation of purification action by analysis of effluent). In order to collect soil from the column only at the time of the final dismantling of the column test, or to collect soil in the column during the test, the soil inside was scraped from a window provided in the middle part of the column. For this reason, the soil in the column can be collected only once, and the soil deep in the column has to be scraped off, and the operation is complicated. However, with the column of the present invention, all such problems are solved.
[0031]
Since all the device members are made of a light-shielding substance, photosynthetic microorganisms can grow and block clogging in columns and pipes to reduce pressure rise, but there is still no possibility depending on the conditions. That's not true. In preparation for such a situation, if a branch pipe is attached to the column wall or node and a pressure gauge or a differential pressure gauge is installed, an early response can be obtained.
[0032]
【Example】
Examples are shown below, but the present invention is not limited to these examples.
[0033]
An outline of the column test apparatus of the present invention and a method for using the column test apparatus will be described with reference to FIG.
The target soil / sand is packed inside the cylindrical column 1 so as to be the same as the contaminated land, and the column is set up in a standing state.
[0034]
The soil temperature in the column is adjusted to 10 to 20 ° C., for example, about 15 ° C., which is the underground temperature at which the soil actually exists, by using temperature atmosphere adjusting means such as air conditioning and temperature-controlled room, and the activity of microorganisms It was made possible to reproduce the computerized state more accurately.
[0035]
A nutrient liquid storage tank 11 and an effluent storage tank 13 are connected to the column 1 by piping. The nutrient solution is supplied to the column 1 using the pump 12 or utilizing the water head difference. The pump 12 is not particularly limited, but a fixed volume pump is preferable.
[0036]
The nutrient solution flows upward in the column, is partially consumed by microorganisms that inhabit the soil, and is stored in the effluent storage tank 13. The nature of the soil, the microbial habitat, and the like are determined by extracting and analyzing the effluent from the upper sampling port 15 ′ of the column 1.
[0037]
The nutrient solution storage tank 11 and the effluent storage tank 13 are stored in the refrigerator 10 (internal temperature 4 ° C.) and maintained at a low temperature. The temperature inside the refrigerator 10 is appropriately set depending on the type of microorganism, the local environment where the soil is placed, and the like, but is usually 10 ° C. or lower, preferably 5 ° C. or lower. Thus, since apparatus members, such as a tank of a test apparatus, are managed at low temperature, a possibility that microbial activity may increase uniformly on a water supply path can be reduced.
[0038]
In order to make the soil inside the column an aerobic environmental condition, the dissolved oxygen concentration of the nutrient solution to be supplied may be adjusted. For this reason, the nutrient solution in the nutrient solution storage tank 11 is bubbled with an oxygen mixed gas supplied via the sterilization air filter 21 by driving the air pump 20 to maintain the dissolved oxygen concentration in an equilibrium state. The oxygen mixed gas is a mixture of oxygen and air (inert gas), and is mixed by supplying air or inert gas from the pipe 23. If the ratio is changed, it is easily adjusted to the desired oxygen concentration. it can. This utilizes the gas-liquid equilibrium regarding the oxygen concentration between the oxygen mixed gas and the liquid phase which is a nutrient solution.
[0039]
A pressure gauge 16 and an effluent sampling port 15 for analysis sampling are installed in front of the column 1. The pressure gauge 16 is installed because bacteria grow abnormally on the soil in the column or the water supply pipe to the column 1 and the column test cannot be continued if the gap is blocked. This is to change the water flow conditions. The pressure gauge is installed with a branch pipe attached to the column or its node, but may be a differential pressure gauge.
[0040]
In order to suppress the propagation of photosynthetic microorganisms, all members of the apparatus such as piping are made of a light shielding material. For example, it is desirable to use a stainless steel tube or the like, or to wrap a Teflon (registered trademark) tube portion with a light shielding material, for example, a sheet of silver paper or an opaque vinyl tape.
[0041]
The structure of the column of the present invention is shown in FIG. The column 1 has a structure (total length: about 1000 mm) in which unit columns 1a (inner diameter is about 20 mm, length is about 150 to 200 mm) are stacked in multiple stages (six stages). The column nodes and nodes are connected to each other by nuts 4 and can be easily disconnected.
[0042]
When analyzing the soil, the nuts may be loosened to separate the nodes, and the amount of soil 2 corresponding to one node may be extracted as the sample for evaluation. In that case, a spacer (similar to the extracted structure) is attached instead. The spacer has an internal filler that can be passed therethrough, and the internal filler may be, for example, a bead ball that can be sterilized, a silicon stopper, or the like.
[0043]
The spacer preferably has the structure of the earth retaining 3 so that itself and the soil filled in the column do not move. The structure of the earth retaining 3 is a disk-like thing having a hole or a widely used net, and the former includes, for example, a plastic disk having a 0.5 mm × 10 mm slit or a 0.5 mm diameter hole, On the other hand, the latter can use the garbage net etc. which are used in the sink of a general household. A preferable mesh size is, for example, about 0.05 to 0.5 mm on one side (diameter).
[0044]
The column can be equipped with pressure gauges at a plurality of locations, but even at one location, an increase in internal pressure can be detected to detect microbial abnormalities in the column.
[0045]
【The invention's effect】
According to the column test apparatus of the present invention, the column is approximated to the soil underground temperature, the nutrient solution and the sampling effluent are controlled at a low temperature, and a means for suppressing the propagation of various bacteria is provided. Can be implemented efficiently, and a highly reliable prior evaluation system can be established for bioremediation. Moreover, the column which comprises this is a structure which can be cut | disconnected by the node part of a unit column, the soil of evaluation object can be subdivided and taken out, a complicated operation is eliminated, and the industrial value is very large.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a soil packed column test system of the present invention.
FIG. 2 is a schematic diagram of a conventional soil packed column test system.
FIG. 3 is a longitudinal sectional view of a column used in the test system of the present invention and an explanatory view of the embodiment.
FIG. 4 is a longitudinal sectional view of a column used in a conventional test system.
[Explanation of sign]
1 column 2 soil 10 refrigerator 11 nutrient solution storage tank 14 sampling effluent tank 15, 15 ′ sampling port 20 air pump

Claims (7)

Nutrient solution from a storage tank (B) storing nutrient solution containing nutrients necessary to activate the decomposed bacteria in a soil-filled column (A) filled with soil and sand mixed with contaminant-degrading bacteria Continuously feeding in upward flow, sampling the effluent flowing out from the column (A), and analyzing the sampled effluent (C) to determine the activation conditions for the degrading bacteria A column test system,
The soil temperature in the column (A) was approximated to the actual soil underground temperature by the temperature atmosphere adjusting means, while the storage tank (B) and the effluent (C) were sealed to suppress the propagation of various bacteria. A continuous water-flowing soil packed column test system characterized by being stored under low temperature in a state. 2. The continuous water-flowing soil-filled column test system according to claim 1, wherein all members constituting the system are coated or formed with a light-shielding substance. The continuous water-flowing soil-filled column test system according to claim 1, wherein a nutrient solution pre-bubbled with an oxygen mixed gas is used to bring the soil in the column (A) to an aerobic environmental condition. . The continuous water-flowing soil packed column test system according to claim 3, wherein the oxygen mixed gas is a mixture of air or an inert gas with a predetermined amount of oxygen. Column (A) consists of a plurality of unit columns stacked in multiple stages, and has a form joined to each node connected to each unit column. Moreover, by separating the soil at the node part, one column of soil is used for evaluation. It has a structure which can be extracted as a sample, The continuous water flow type soil-filled column test system of Claim 1 characterized by the above-mentioned. Instead of the extracted soil, a spacer having an internal filler that has the same shape as the soil and is capable of passing liquid is disposed in a void portion that is created after the extraction. 5. The continuous water-flowing soil-filled column test system according to 5. The continuous water-flowing soil-filled column according to claim 1, wherein a pressure gauge or a differential pressure gauge is installed in the column (A) or a water supply pipe connecting the column (A) and the storage tank (B). Test system.

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