CN114082779B - Accelerated test method and device for long-term remediation effectiveness of contaminated soil - Google Patents
Accelerated test method and device for long-term remediation effectiveness of contaminated soil Download PDFInfo
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- CN114082779B CN114082779B CN202111424994.6A CN202111424994A CN114082779B CN 114082779 B CN114082779 B CN 114082779B CN 202111424994 A CN202111424994 A CN 202111424994A CN 114082779 B CN114082779 B CN 114082779B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/08—Reclamation of contaminated soil chemically
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/10—Reclamation of contaminated soil microbiologically, biologically or by using enzymes
- B09C1/105—Reclamation of contaminated soil microbiologically, biologically or by using enzymes using fungi or plants
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C2101/00—In situ
Abstract
The invention relates to an accelerated test method and device for the long-term remediation effectiveness of contaminated soil. The accelerated test method for the long-term repairing performance of the polluted soil comprises the following steps: s1: acquiring soil and soil characteristic information of a field to be detected; s2: setting a field micro-ecology according to the soil characteristic information, domesticating a microbial community under the condition of the field micro-ecology, enriching and preparing a microbial liquid; s3: injecting the microbial liquid into the soil for treatment, respectively collecting the liquid and the soil after the treatment is finished, and detecting the leaching rate of heavy metals after the collected soil is dried; s4: and (5) repeating the step (S3) to obtain a graph of the change of the heavy metal leaching rate along with the injection times until the stabilization effect is invalid. The accelerated test method can accurately and quantitatively reflect the long-term effect of the stabilization and remediation of the heavy metal soil in the actual field.
Description
Technical Field
The invention relates to the technical field of pollution control, in particular to an accelerated test method and device for the long-term remediation effectiveness of polluted soil.
Background
Heavy metals are difficult to completely remove from soil, if the heavy metals are separated in the modes of soil leaching, thermal desorption (effective for mercury) and the like, irreversible damage is often caused to the ecological environment of the soil, and the repaired soil is difficult to adapt to the requirement of recycling of greening land. Therefore, the most common remediation technology for soil heavy metal pollution at present is the stabilization of heavy metals, and the conversion of the geochemical form of the heavy metals is realized by adding exogenous remediation materials, namely, the soil heavy metals are converted into inert forms which are inactive, difficult to leach and difficult to cause environmental risks from active, easy-to-leach, easy-to-enrich and easy-to-migrate water-soluble exchange states and carbonate binding states through mechanisms such as surface complexation, precipitation and the like. The repair technology becomes the mainstream repair technology of the heavy metal contaminated soil.
The stabilization and restoration technology of the heavy metal has the characteristics of easy construction, low disturbance and low cost. However, since heavy metals are not removed from the soil, but are temporarily passivated, under the action of environmental aging processes such as rainfall leaching, chemical transformation, biological transplantation and the like, heavy metal elements are reactivated and are transformed into a geochemical form with high environmental risk. Therefore, it is very necessary to evaluate the long-term stability of stabilization repair.
The most direct way to evaluate the long-term stability of a stabilized restoration is to take a sample and monitor the field after restoration for a long time. However, in most cases, long-term monitoring is very difficult due to the practical requirements of site recycling. Based on the method, some researches and developments are carried out on an accelerated aging method and an accelerated aging device based on the key aging effect of rainfall eluviation, so that the simulation of the stabilization and long-term effect of the heavy metal in the soil under the rainfall condition is realized, and the research is also coupled with the illumination process of the surface soil on the basis of the rainfall eluviation. However, site remediation often restores deeper formations, and the site is usually covered with geomembranes (e.g., HDPE films) after remediation, and the probability of continuous rainfall scouring or light exposure of these deep soils is almost 0. Meanwhile, the previous studies are qualitative aging, and quantitative aging cannot be realized. In conclusion, it is difficult to accurately and intuitively reflect the long-term stability of the stabilized restoration of the restored site in the aforementioned research.
Disclosure of Invention
Based on the method, the accelerated test method and the accelerated test device for the contaminated soil remediation long-term effect can accurately and quantitatively reflect the stabilization remediation long-term effect of the heavy metal soil in the actual field.
In a first aspect of the present invention, an accelerated test method for the long-term efficacy of contaminated soil remediation is provided, which comprises the following steps:
s1: acquiring soil and soil characteristic information of a field to be detected, wherein the soil characteristic information comprises a pH value, an oxidation-reduction potential (Eh) value and a stratum main control mineral variety; the site to be detected is a stabilized polluted site;
s2: setting a field micro-ecology according to the soil characteristic information, domesticating a microbial community under the condition of the field micro-ecology, enriching, and preparing a microbial liquid;
s3: injecting the microbial inoculum into the soil for treatment, collecting the soil after the treatment is finished, and detecting the leaching rate of heavy metals after the collected soil is dried;
s4: and (5) repeating the step (S3) to obtain a graph of the change of the heavy metal leaching rate along with the injection times until the stabilization effect is invalid.
In one embodiment, in step S3, the process further includes a step of injecting an organic acid solution.
In one embodiment, in step S3, before the injection, the pH value and the oxidation-reduction potential (Eh) value of the organic acid solution are adjusted according to the pH value and the oxidation-reduction potential (Eh) value in the soil characteristic information.
In one embodiment, the injection amount of the organic acid solution in step S3 is 0 to 20000mg of organic acid/kg of soil.
In one embodiment, in step S2, the domestication mode is liquid culture for 7-21 days; and/or
In the step S2, the enrichment multiple is 10-100 times; and/or
In step S3, the treatment time is 1 to 4 days.
In one embodiment, in step S1, the distance between the soil and the surface layer is 0.5m to 10m; and/or
In the step S1, the stabilization treatment depth of the field to be detected is D, and the 2m-less ground is less than or equal to 10m.
In one embodiment, in step S2, the setting of the site micro-ecology comprises compatibility of the culture medium, pH adjustment, and oxidation-reduction potential adjustment; wherein, the compatibility of the culture medium is shown in the following table 1:
TABLE 1
In one embodiment, in step S2, domestication is performed in a microorganism liquid culture device, wherein a plurality of partition plates are arranged in a cavity of the microorganism liquid culture device; the separator plate has a recess for depositing formation prime minerals.
In one embodiment, in step S3, the treatment is performed in a biochemical aging column, and the soil is filled in a cavity of the biochemical aging column; preferably, the ratio of the height of the soil filling to the maximum inner diameter of the biochemical aging column is (3-6): 1;
the two ends of the biochemical aging column are respectively provided with a liquid inlet and a liquid outlet, and the thickness of the inner wall of the biochemical aging column at the z-height position is S in the extending direction of the liquid inlet to the liquid outlet z ，
Wherein v is the kinematic viscosity of water, u 0 The speed of injecting the microbial solution or the organic acid,
q is the flow rate of the microbial solution or the organic acid, and the unit is m 3 And/s, y is the maximum inner diameter of the biochemical aging column.
The invention provides an accelerated test device for the long-term repair of contaminated soil, which comprises a microbial liquid incubator and a biochemical aging column;
the two ends of the biochemical aging column are respectively provided with a liquid inlet and a liquid outlet, and the thickness of the inner wall of the biochemical aging column at the z-height position is S in the direction extending from the liquid inlet to the liquid outlet z ，
Wherein v is the kinematic viscosity of water, u 0 The speed of injecting the microbial solution or the organic acid,
q is the flow rate of the microbial solution or the organic acid, and the unit is m 3 Y is the maximum inner diameter of the biochemical aging column; the cavity of the biochemical aging column is used for filling soil of a field to be tested;
the microorganism liquid incubator is communicated to the liquid inlet of the biochemical aging column through a pipeline and is used for conveying microorganism liquid; a plurality of partition plates are arranged in the cavity of the microorganism liquid culture device; the partition board is provided with a sunken part and is used for depositing stratum main control minerals of soil of a field to be detected; the microorganism liquid culture device is also provided with a first controller, and the first controller is used for receiving the pH value and the oxidation-reduction potential (Eh) value of soil in a field to be detected;
optionally, the device further comprises an organic acid mixing device which is communicated to the liquid inlet of the biochemical aging column through a pipeline and used for conveying the organic acid solution; the organic acid mixing device is provided with a second controller, and the second controller is used for receiving the pH value and the oxidation-reduction potential (Eh) value of soil in a field to be detected.
According to the accelerated test method for the contaminated soil remediation long-term effect, microorganism domestication is carried out according to soil characteristic information of a site to be tested, the microorganism domestication is injected into soil obtained by the site to be tested to carry out an accelerated aging test, and test verification shows that the remediation long-term effect of stabilized soil in an actual environment can be simulated more accurately, and particularly the remediation long-term effect of deep soil can be reflected accurately. Meanwhile, the accelerated test method is short in time consumption and can quantify the repair process.
And organic acid is further added for accelerated aging, so that the soil with different depths can be simulated, and the application range of the method is expanded.
Drawings
FIG. 1 is a schematic view of an accelerated test apparatus for contaminated soil remediation longterm performance according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of the principle of microbial cultivation in one embodiment of the present invention;
FIG. 3 is a schematic view of a microbial liquid culture vessel according to an embodiment of the present invention;
FIG. 4 is a schematic illustration of the pH profile of soils of varying depths in accordance with an embodiment of the present invention;
FIG. 5 is a schematic diagram of the Eh law for soils of different depths in accordance with an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of a biochemical aging column according to an embodiment of the present invention;
FIG. 7 is a schematic structural diagram of an organic acid mixing device according to an embodiment of the present invention;
FIG. 8 is an aging curve obtained by an accelerated test of example 1 of the present invention;
FIG. 9 is an aging curve obtained by the accelerated test of example 2 of the present invention.
Detailed Description
The accelerated test method and apparatus for the long-term remediation efficacy of contaminated soil according to the present invention will be described in detail with reference to the following embodiments. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
As used herein, the term "and/or", "and/or" includes any and all combinations of two or more of the associated listed items, including any two or any more of the associated listed items, or all of the associated listed items.
As used herein, "one or more" refers to any one, any two, or any two or more of the listed items.
The terms "first aspect," "second aspect," and the like, as used herein, are for descriptive purposes only and are not to be construed as indicating or implying a relative importance or quantity, nor are they to imply that the importance or quantity of the technical feature being indicated is implicitly indicated. Moreover, "first," "second," etc. are used for non-exhaustive enumeration description purposes only and should not be construed as being inclusive of numbers.
In the present invention, the technical features described in the open type include a closed technical solution composed of the listed features, and also include an open technical solution including the listed features.
In the present invention, the numerical intervals are regarded as continuous, and include the minimum and maximum values of the range and each value between the minimum and maximum values, unless otherwise specified. Further, when a range refers to an integer, each integer between the minimum and maximum values of the range is included. Further, when multiple range-describing features or characteristics are provided, the ranges may be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein.
The percentage contents referred to in the present invention mean, unless otherwise specified, mass percentages for solid-liquid mixing and solid-solid phase mixing, and volume percentages for liquid-liquid phase mixing.
The percentage concentrations referred to in the present invention are, unless otherwise specified, the final concentrations. The final concentration refers to the ratio of the additive component in the system to which the component is added.
The temperature parameter in the present invention is not particularly limited, and may be a constant temperature treatment or a treatment within a certain temperature range. The constant temperature process allows the temperature to fluctuate within the accuracy of the instrument control.
It is understood that in the process of the present invention involving liquid culture, the "solid-to-liquid ratio" of the material addition refers to the mass ratio or mass percentage of the material relative to the liquid culture medium.
The invention provides an accelerated test method for the long-term repairing performance of polluted soil, which comprises the following steps:
s1: acquiring soil and soil characteristic information of a field to be detected, wherein the soil characteristic information comprises a pH value, an oxidation-reduction potential (Eh) value and a stratum main control mineral variety; understandably, the site to be detected is a polluted site after stabilization treatment;
s2: setting a field micro-ecology according to the soil characteristic information obtained in the step S1, domesticating a microbial community under the condition of the field micro-ecology, enriching, and preparing a microbial liquid;
s3: injecting the microbial liquid prepared in the step S2 into soil obtained from a field to be detected for treatment, collecting the soil after the treatment is finished, and detecting the leaching rate of heavy metals after drying the collected soil;
s4: and (4) repeating the step (S3) to obtain a graph of the change of the heavy metal leaching rate along with the injection times until the stabilization effect is invalid.
Specifically, step S1 is a step of material and information to be measured.
Referring to fig. 1, a pH-ORP online monitoring instrument may be disposed in a monitoring well 101 of a site 100 to be tested, and a pH value and an Eh value of soil are obtained and transmitted back to an accelerated test device through a controller. Meanwhile, corresponding soil is collected, and stratum main control mineral types are obtained through site investigation. In addition, the composition, the dosage and the like of the stabilizing agent can be obtained for test recording.
In one example, in step S1, the distance between the soil of the field to be measured and the surface layer is obtained to be 0.5m to 10m.
In one example, in step S1, the stabilization depth of the field to be measured is D, and 2-over-D is less than or equal to 10.
Specifically, step S2 is a microorganism culturing step.
Without limitation, the principle is shown in fig. 2: (a) The dead microorganisms settle and are adsorbed on the inner surface and the outer surface of the main control mineral to realize attachment and fixation; (b) The main control minerals can also absorb nutrient elements, so that the growth rate of microorganisms is reduced; (c) proliferating the viable microorganisms suspended in the liquid. The main control minerals have the following functions: (d) Selecting the soil microbial community directionally to simulate the community structure closest to the actual stratum with different depths; (e) By adsorbing the nutrient elements, the growth rate of the microorganisms is reduced, so that the microorganisms do not grow too fast to cross the logarithmic phase to reach the aging phase.
Referring to fig. 1, information obtained from the site 100 to be tested is transmitted back to the microbial liquid incubator 200.
In one example, a plurality of partition boards 201 are arranged in the cavity of the microorganism liquid culture device 200; the spacer 201 has a recess for depositing formation prime minerals.
Further, referring to fig. 3, the partition 201 is V-shaped with an included angle of 90 °, a side length of c, an opening width of b,
the height is (1/2) b. The V-shaped groove with the included angle is provided with a main control mineral deposition point, which is beneficial to the attachment and growth of microorganisms. Optionally, c =3cm to 5cm.
Further, referring to fig. 3, the inner width x of the cavity of the microbial liquid incubator 200 is 0.5 to 1.5 times the inner length. Alternatively, x = 20-30 cm. The plurality of clapboards 201 are arranged in the cavity of the microorganism liquid culture device 200 in layers, the even clapboards 201 in the clapboard 201 in the same layer are arranged in a staggered mode, and optionally, after the staggered mode is arranged, the distance h between the layer formed by the even clapboards and the original layer 0 And (c) =0.5 cm-1 cm. Understandably, x =2a + x b, a is the distance between the partition board 201 nearest to the wall of the microbial liquid incubator 200 and the wall of the chamber, n x Is the total number of separators 201 in the same layer. Alternatively, a =0.5cm to 1cm. Optionally, the distance between the closest layer of partition plate to the feed inlet of the microorganism liquid culture device 200 and the feed inlet is h 1 And (0.2-0.5) x. Alternatively, the distance between the bottom and the closest layer of partition plates to the bottom of the microorganism liquid culture incubator 200 is h = (0.2 to 0.3) x. Optionally, the number of layers (including staggered layers) n of the separator 201 y And (3) =3 to 5. Alternatively, the material of the partition 201 may be plastic, for example.
In one example, the microbial liquid incubator 200 is further provided with a first controller for receiving pH and oxidation-reduction potential (Eh) information of soil of a site to be tested.
It is understood that the materials in the microbial liquid incubator 200 can be mixed by aeration.
In one example, the setting of the site micro-ecology in step S2 includes the compatibility of the culture substrate, the adjustment of pH, and the adjustment of oxidation-reduction potential.
Wherein the pH is adjusted by adding hydrochloric acid and/or sodium hydroxide. Eh is regulated by introducing oxygen (O) 2 ) And nitrogen (N) 2 ) The process is carried out. At the same time, pH and Eh can be monitored by a pH/ORP electrode.
The culture substrate is introduced from the inlet of the microbial liquid incubator 200 by a peristaltic pump. The compatibility of the culture mediums of the soil at different depths in the field to be tested and the dominant bacteria species in the microbial community are shown in the following table 2:
TABLE 2
Wherein the type 1. MnO (MnO) x X =1 to 1.5 in (1), specifically MnO x Is MnO 2 、Mn 2 O 3 Or a mixture of the two.
In one example, in step S2, the liquid culture is performed for 7 to 21 days.
In one example, the enrichment factor in step S2 is 10 to 100 times. The fold enrichment can be monitored, for example, by a turbidimeter.
In addition, the results of the studies on dominant species under different conditions of the main mineral, pH and Eh are shown in tables 3 to 5 below.
TABLE 3 dominant species under different action of Master minerals
TABLE 4 dominant species under different pH
TABLE 5 dominant species under different Eh effects
The results of the study on the pH and Eh laws of the soils at different depths are shown in fig. 4 to 5.
By combining tables 3-5 and figures 4-5, the site microecology can be set for the soil with different characteristic information, and accurate and quantitative accelerated aging tests of the long-term effect of contaminated soil remediation can be realized.
Specifically, step S3 is a biochemical aging step.
Referring to fig. 1, a microbial liquid cultured in a microbial liquid culture device 200 is injected into a biochemical aging column 300 from the bottom through a pipeline. Meanwhile, the soil obtained in step S1 is filled in the cavity of the biochemical aging column 300.
In one example, referring to FIG. 6, the biochemical aging column 300 has a liquid inlet 301 and a liquid outlet 302 at two ends thereof, respectively, and the thickness S of the inner wall 303 of the biochemical aging column 300 at the z-height in the direction extending from the liquid inlet 301 to the liquid outlet 302 z ，
Wherein v is the kinematic viscosity of water, u 0 The speed at which the microbial broth (or organic acid solution, see below) is injected,
q is the flow rate of the injected microbial liquid (or organic acid solution) and the unit is m 3 And/s, y is the maximum inner diameter of the biochemical ageing column.
The design principle of the biochemical aging column 300 is as follows:
the flow direction of the liquid in the biochemical aging column 300 is controlled by the pressure. According to the Bernoulli principle, the pressure is small where the flow velocity is large. The cross section area of the liquid outlet 302 of the biochemical aging column 300 is smaller than that of the liquid inlet 301, and the pressure intensity is smaller than that of the liquid inlet 301, so that the microbial liquid (or the organic acid solution) is pushed upwards, and the boundary layer separation can be avoided.
According to Bernoulli' S equation, ρ is constant for incompressible homogeneous fluid, and the following equation ([ delta ] is equal to S here) z )：
Assuming that the velocity distribution of the laminar boundary layer is the same as the velocity distribution of the laminar flow in the aged column flow, that is:
in the formula, r 0 R is the distance between the inner diameter of the aging column and the cross section and the center of the aging column, r0 in the aging column corresponds to delta in the boundary layer, r is (delta-y) and u max Corresponds to u 0 U corresponds to u z The above formula can be rewritten as
Or
From the relation τ of shear stress and boundary layer thickness 0 ＝τ 0 (δ), according to newton's law of internal friction. And the shear stress y =0 in the aging column, and the substitution into the Newton's internal friction law can obtain:
where μ is the dynamic viscosity of the fluid, μ = ρ v. The minus sign indicates that the shear stress and the aged column are in the opposite z-axis direction. And (3) obtaining the absolute value after sorting and simplification:
description of the above equation 0 Inversely proportional to δ. Substituting the above equation into the equation to obtain
The following can be obtained:
integrating to obtain:
when z =0, δ =0, resulting in C =0
Due to the fact that
The above formula is simplified to
And (4) according to the (×) design curve, and by means of 3D printing and the like, obtaining the biochemical aging column 300.
In one example, in step S3, the time for the post-treatment after the injection of the microbial solution is 1 to 4 days.
In one example, in step S3, the ratio of the height of the soil filling in the biochemical aging column 300 to the maximum inner diameter of the biochemical aging column 300 is (3-6): 1. thus, it is ensured that no preferential flow is generated and the mixing is uniform.
Further, in one example, the step S3 includes, while injecting the microbial liquid, a step S31: an organic acid solution is injected.
Referring to fig. 7, an organic acid solution is disposed in an organic acid mixing device 400. The organic acid mixing device 400 has a structure substantially similar to that of the microbial liquid culture device 200, and a stirrer 401 is additionally provided at the bottom of the microbial liquid culture device 200. The structure of which is not described in detail herein. Therefore, the microorganism liquid culture device 200 can be modified, and meanwhile, the existence of the partition plate 201 can promote the sufficient mixing of the acid liquor. Alternatively, the paddle length r =5cm to 10cm of the paddle of the stirrer 401.
In one example, the organic acid solution is adjusted to its own pH and Eh according to the pH and Eh in the soil characteristic information before injection. Wherein the pH is adjusted by adding hydrochloric acid and/or sodium hydroxide. Eh is regulated by introducing oxygen (O) 2 ) And nitrogen (N) 2 ) The process is carried out. At the same time, pH and Eh can be monitored by a pH/ORP electrode.
In one example, the organic acid mixing device 400 is further provided with a second controller for receiving information of a pH value and an oxidation-reduction potential (Eh) value of soil of a field to be measured.
Referring to fig. 1, the organic acid solution prepared by the organic acid mixing device 400 is injected into the biochemical aging column 300 from the bottom through a pipe.
In one example, the organic acid solution is injected in the step S3 in an amount of 0 to 20000mg of organic acid per kg of soil. It is understood that when the amount of the organic acid solution is 0, that is, when the organic acid solution is not added, it is preferable to add the organic acid solution to the soil near the surface layer (the distance between the soil and the surface layer is 0.5m to 1 m), and the amount of the organic acid solution is more than 0 and 20000mg or less of the organic acid per kg of the soil.
In one example, in step S3, when the distance between the soil of the field to be measured and the surface layer is 0.5m to 1m, an organic acid solution may be injected.
Alternatively, the organic acid may be one or more of citric acid and oxalic acid.
In one example, in step S3, after the completion of the treatment, the soil is collected and the leaching rate of the heavy metal is performed, and the liquid obtained by the treatment may be collected, and the concentration, pH, eh, and the like of the heavy metal in the liquid may be detected, thereby further investigating the relationship between the microbial community in the soil and the soil remediation.
Further, in one example, site micro-ecological regulatory parameters applicable to accelerated aging of deep soils (beyond this pH and ORP range does not conform to natural conditions): the pH variation range is 2-12; the ORP variation range is-550 mV- +550mV; the concentration of the organic acid solution is 0-20000 mg of organic acid/kg of soil.
Without limitation, the method for measuring the leaching rate of heavy metals may employ a conventional method in the art, such as a sulfuric acid-nitric acid method, a horizontal shaking method, an acetic acid buffer solution method, and the like.
In one example, the heavy metal type of the soil of the site to be tested is selected from one or more of lead, cadmium, copper, zinc, arsenic, chromium (hexavalent), mercury, nickel, antimony and manganese.
The invention also provides an accelerated test device for the long-term remediation of contaminated soil, which comprises a microbial liquid incubator 200 and a biochemical aging column 300. The microorganism liquid incubator 200 is communicated to the liquid inlet of the biochemical aging column 300 through a pipeline and is used for conveying microorganism liquid.
Further, the device comprises an organic acid mixing device 400, wherein the organic acid mixing device 400 is communicated to the liquid inlet of the biochemical aging column 300 through a pipeline and is used for conveying an organic acid solution.
Specifically, the structures of the microorganism liquid culture device 200, the biochemical aging column 300 and the organic acid mixing device 400 are the same as those described above, and are not described herein again.
Specific examples are as follows.
Example 1
The test object of the embodiment is a typical lead and cadmium polluted site, the lead concentration of the soil is 3510mg/kg, the cadmium concentration is 86mg/kg, the stabilizing material is lime, and the adding amount is as follows: 0.5% wt (relative to soil), the depth of restoration was 4.5m.
Device parameters:
in a microbial liquid culture device, c =3cm x ＝3，a＝1cm，x＝23.2cm，h＝2.5cm，h 0 ＝1cm，n y ＝3，h 1 ＝6cm；
In a biochemical aging column, y =2cm, z =10cm, q =3 × 10 -5 m 3 /s，v＝1.003×10 -6 m 2 (s) completely filling the aging column with soil; 2 layers of 200-mesh nylon nets are respectively paved at the upper end and the lower end to prevent the soil from being sprayed out under the action of the bacterial liquid flow;
in the organic acid mixing device, r =5cm, and the rest parameters are the same as those of the microbial liquid incubator.
The process steps and parameters are as follows:
the typical lead-cadmium composite pollution site is a typical steel smelting and processing manufacturing site, and the initial examination and detailed examination report of the site shows that the surface soil is rich in iron oxide (the content of Fe obtained by XRF test is 2.5%), but the main control minerals are still silicon dioxide; the laser particle size test result shows that the clay (0.002 mm) content of the deep soil (the distance between the soil and the surface layer is 3 m) is 55%, the powder particle (0.002-0.05 mm) content is 32%, the sand particle (0.05 mm) content is 13%, and the main mineral is clay. Determined by small test and field pilot test lime is used as a stabilizing material. Lime can effectively increase the pH value of soil, thereby realizing the synergistic stabilization of multi-cation pollutants such as lead, cadmium and the like. Backfilling the stabilized soil to the original site, and covering with thin-layer clay; and covering clean soil with the thickness of 30cm on the clay layer for greening and recycling.
Taking back 30kg of stabilized sample as original soil for accelerating aging (stored at 20kg, dried at 60 ℃ to limit microbial activity) before backfilling after adding the stabilizing and repairing material, and domesticating a microbial community under the field microecological condition (liquid culture, the solid-liquid ratio is 1:20, fresh soil is used), enriching, and preparing a microbial liquid. Specifically, the liquid culture was divided into two parallel experiments, in which, in addition to 1 3 Mass ratio 2: montmorillonite = 1.
Determining the microecological conditions of the site: establishing a monitoring well in a stabilization area to acquire pH and Eh information at a 3m depth of a field backfill area, and measuring: the pH was 8.49 and the eh was-175 mV.
The retrieved fresh soil was mixed with the corresponding mineral according to the above ratio, placed in a sealed container for shaking culture, using beef extract peptone as a total nutrient medium (20 mL of water per 1g of beef extract peptone to prepare a liquid medium), adjusting pH with hydrochloric acid and sodium hydroxide, and adjusting Eh with hydrogen peroxide and sodium sulfide. Culturing for 14 days, and measuring by a turbidimeter to obtain a bacterial liquid with the enrichment factor of 85 times. And (5) applying the bacterial liquid to the field for taking back and accelerating aging of the dried soil. The mixing time of the bacterial liquid and the soil in a single batch is 4 days. The bacterial liquid is injected into the dosage (1PV = 16mL) of 10 soil gaps (PV soaks the gaps in the first 9 PV, because the bacterial liquid is continuously injected and the solution with the dosage of the first 9 gaps is discharged out of the system, the later PV realizes the bacterial liquid loading and aging treatment), so that the soil is soaked by the microbial liquid; after 4 days, it was discharged, which was called 1 operation. A total of 5 experiments were performed, each group taking out soil samples after 1, 2, 3, 4, 5 mixes, respectively.
Group B was performed according to the procedure described above, and group A was performed according to the procedure described above while adding an organic acid (10000 mg citric acid/kg soil) before biochemical aging. Adding: adding citric acid solid powder into soil loaded in the biochemical aging column according to the mixing amount of 1% by mass, then adding 1PV deionized water to dissolve the citric acid solid powder, and stirring the mixture uniformly. Then injecting bacterial liquid according to the steps.
Meanwhile, a soil sampler is adopted to drill holes and sample to obtain samples (shown in table 6) with different depths, the collected soil samples are taken back to a laboratory to be dried, ground and sieved to carry out leaching experiments, and the results are compared with accelerated aging results.
The leaching rate of heavy metals in the available state of soil was obtained according to the TCLP method (the leaching solution concentration was tested by shaking with an acetic acid solution of pH =2.88 at a solid-to-liquid ratio of 1.
The biochemical aging method gave an aging curve as shown in FIG. 8.
Example 2
The test object of the embodiment is a typical hexavalent chromium polluted site, the concentration of hexavalent chromium in the soil is 129mg/kg, the stabilizing material is ferrous sulfate, and the adding amount is as follows: 1% wt (relative to the soil), the depth of repair was 4.5m.
Device parameters:
in a microbial liquid culture device, c =3cm x ＝3，a＝1cm，x＝23.2cm，h＝2.5cm，h 0 ＝1cm，n y ＝3，h 1 ＝6cm；
In a biochemical aging column, y =2cm, z =10cm, q =3 × 10 -5 m 3 /s，v＝1.003×10 -6 m 2 (s) completely filling the aging column with soil; 2 layers of 200-mesh nylon nets are respectively paved at the upper end and the lower end to prevent the soil from being sprayed out under the action of the bacterial liquid flow;
in the organic acid mixing device, r =5cm, and the rest parameters are the same as those of the microbial liquid incubator.
The process steps and parameters are as follows:
the typical hexavalent chromium polluted site is an electroplating plant site, and is repaired by ferrous sulfate through a small test and a middle test. The ferrous sulfate has good reducibility, and can realize long-term stabilization of pollutants by reducing hexavalent chromium into trivalent chromium. The site is repaired in a mode of in-situ injection of ferrous sulfate. And (3) taking 30kg of stabilized sample back 2m after the stabilized repairing material is added (the difference between the surface layer environment and the deep layer environment is smaller at the moment), taking the stabilized sample as original soil for accelerating aging (stored at 20kg, dried at 60 ℃ to limit the activity of microorganisms), and domesticating a microbial community (liquid culture, the solid-liquid ratio is 1:20, fresh soil) under the field microecological condition, enriching, and preparing to obtain a microbial liquid. Specifically, the liquid culture was divided into two parallel experiments, in which 1% of mixed iron and aluminum minerals (FeOOH and Al (OH)) were added to the liquid-solid ratio described in table 1, except for 1 3 3 to 1) (group C, the subsequent aging process of the group adds organic acid),and SiO 5 in a mass ratio of 2% to the solid-liquid ratio described in Table 1 2 And MnO with MnO 2 Mixture of (D), group of subsequent aging without addition of organic acid).
Determining the microecological conditions of the site: establishing a monitoring well in a stabilization area to acquire pH and Eh information at a 2m depth position of a field, and measuring: the pH was 6.93 and the eh was-230 mV.
The retrieved fresh soil was mixed with the corresponding mineral according to the above ratio, placed in a sealed container for shaking culture, using beef extract peptone as a total nutrient medium (20 mL of water per 1g of beef extract peptone to prepare a liquid medium), adjusting pH with hydrochloric acid and sodium hydroxide, and adjusting Eh with hydrogen peroxide and sodium sulfide. Culturing for 14 days, and measuring by a turbidimeter to obtain a bacterial liquid with an enrichment factor of 67 times. The bacterial liquid is used for accelerating aging. The single batch mixing time of the bacterial liquid and the soil is 2 days. The bacterial liquid is injected into the dosage (1PV = 16mL) of 10 soil gaps (PV soaks the gaps in the first 9 PV, because the bacterial liquid is continuously injected and the solution with the dosage of the first 9 gaps is discharged out of the system, the later PV realizes the bacterial liquid loading and aging treatment), so that the soil is soaked by the microbial liquid; after 4 days, it was discharged, referred to as 1 operation. A total of 5 experiments were performed, each group taking out soil samples after 1, 2, 3, 4, 5 mixes, respectively.
Group D was performed according to the above procedure, and group C was performed according to the above procedure while adding organic acid (20000 mg oxalic acid/kg soil) before biochemical aging. Adding: adding oxalic acid solid powder into soil loaded in the biochemical aging column according to the mixing amount of 1% by mass, then adding 1PV deionized water to dissolve the oxalic acid solid powder, and stirring the mixture uniformly. Then injecting bacterial liquid according to the steps.
The leaching rate of the heavy metals in the available state of the soil was obtained according to the TCLP method (the leaching solution concentration was tested by shaking with an acetic acid solution of pH =2.88 at a solid-to-liquid ratio of 1.
The biochemical aging method gave an aging curve as shown in FIG. 9.
And (4) verifying the result:
and (3) synchronously carrying out long-term detection on the restoration of the lead and cadmium polluted site in the real natural environment aiming at the same test object in the embodiment 1. The TCLP analysis found the effective state contents at the beginning of stabilization (t = 0), at 4 months of stabilization, at 8 months of stabilization and at 1 year of stabilization, respectively, as shown in table 6 below.
TABLE 6
Comparing with the aging curve chart 8 of example 1, it can be seen that the effect of one cycle in example 1 is approximately equal to the aging process of 4 months in nature, and the increasing trend of cadmium-lead leaching in nature is consistent with that in the accelerated aging simulation. The aging rule at 0.5m under natural conditions can be well simulated by culturing microorganisms with iron-aluminum mixed minerals and adding organic acid; the aging rule at 3m under natural conditions can be well simulated by culturing microorganisms with mixed clay minerals without adding organic acid.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, so as to understand the technical solutions of the present invention specifically and in detail, but not to be understood as the limitation of the protection scope of the invention. It should be noted that various changes and modifications can be made by those skilled in the art without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. It should be understood that the technical solutions provided by the present invention, which are obtained by logical analysis, reasoning or limited experiments, are within the scope of the appended claims. Therefore, the protection scope of the present invention should be subject to the content of the appended claims, and the description and the drawings can be used for explaining the content of the claims.
Claims (11)
1. An accelerated test method for the long-term effect of contaminated soil remediation is characterized by comprising the following steps:
s1: acquiring soil and soil characteristic information of a field to be detected, wherein the soil characteristic information comprises a pH value, an oxidation-reduction potential value and a stratum main control mineral variety; the field to be detected is a stabilized polluted field;
s2: setting a field micro-ecology according to the soil characteristic information, domesticating a microbial community under the condition of the field micro-ecology, enriching and preparing a microbial liquid;
s3: injecting the microbial inoculum into the soil for treatment, collecting the soil after the treatment is finished, and detecting the leaching rate of heavy metals after the collected soil is dried; the treatment process also comprises a step of injecting an organic acid solution, the treatment is carried out in a biochemical aging column, and the soil is filled in a cavity of the biochemical aging column;
the two ends of the biochemical aging column are respectively provided with a liquid inlet and a liquid outlet, and the thickness of the inner wall of the biochemical aging column at the z-height position is S in the direction extending from the liquid inlet to the liquid outlet z ，
Wherein v is the kinematic viscosity of water, u 0 The injection speed of the microbial solution or the organic acid solution,
q is the flow rate of the microbial solution or the organic acid solution, and the unit is m 3 Y is the maximum inner diameter of the biochemical aging column;
s4: and (5) repeating the step (S3) to obtain a graph of the change of the heavy metal leaching rate along with the injection times until the stabilization effect is invalid.
2. The accelerated test method of contaminated soil remediation longevity according to claim 1, wherein in step S3, before injection, the pH value and oxidation-reduction potential value of the organic acid solution are adjusted according to the pH value and oxidation-reduction potential value in the soil characteristic information.
3. The accelerated test method of contaminated soil remediation longevity according to claim 1, wherein in step S3, the amount of the organic acid solution injected is 0 to 20000mg of organic acid/kg of soil.
4. The accelerated test method of contaminated soil remediation longevity according to claim 3, wherein in step S3, the injection amount of the organic acid solution is greater than 0 and 20000mg or less of organic acid/kg of soil.
5. The accelerated test method for contaminated soil remediation longevity according to any one of claims 1 to 4, wherein in step S2, the domestication mode is liquid culture for 7 to 21 days; and/or in the step S2, the enrichment multiple is 10-100 times; and/or
In step S3, the treatment time is 1 to 4 days.
6. The accelerated test method of contaminated soil remediation longevity according to any one of claims 1 to 4, wherein in step S1, the distance between the soil and the surface layer is 0.5m to 10m; and/or
In the step S1, the stabilization treatment depth of the field to be detected is D, and 2m is less than or equal to 10m.
7. The accelerated test method of contaminated soil remediation longevity according to claim 6, wherein in step S2, the setting of site micro-ecology includes compatibility of culture medium, pH adjustment, and oxidation-reduction potential adjustment; wherein, the compatibility of the culture medium is shown in the following table 1:
TABLE 1
8. The accelerated test method for contaminated soil remediation longevity according to any one of claims 1 to 4, wherein in step S2, domestication is performed in a microbial liquid culture vessel, and a plurality of partition plates are provided in a cavity of the microbial liquid culture vessel; the separator plate has a recess for depositing formation prime minerals.
9. The accelerated test method for contaminated soil remediation longevity according to any one of claims 1 to 4, wherein the ratio of the height of the soil packing to the maximum inner diameter of the biochemical aging column is (3-6): 1.
10. An accelerated test device for the long-term effectiveness of contaminated soil remediation is characterized by comprising a microbial liquid incubator and a biochemical aging column;
the two ends of the biochemical aging column are respectively provided with a liquid inlet and a liquid outlet, and the thickness of the inner wall of the biochemical aging column at the z-height position is S in the direction extending from the liquid inlet to the liquid outlet z ，
Wherein v is the kinematic viscosity of water, u 0 The speed of injecting the microbial liquid or the organic acid,
q is the flow rate of the microbial solution or the organic acid, and the unit is m 3 S, y is the maximum inner diameter of the biochemical aging column; said raw material isThe cavity of the aging column is used for filling soil of a field to be tested;
the microorganism liquid incubator is communicated to the liquid inlet of the biochemical aging column through a pipeline and is used for conveying microorganism liquid; a plurality of partition plates are arranged in the cavity of the microorganism liquid culture device; the partition board is provided with a sunken part and is used for depositing stratum main control minerals of soil of a field to be detected; the microbial liquid culture device is also provided with a first controller, and the first controller is used for receiving the pH value and the oxidation-reduction potential value of soil in a field to be detected.
11. The accelerated test device of the contaminated soil remediation longevity of claim 10, further comprising an organic acid mixing device, wherein the organic acid mixing device is communicated to the liquid inlet of the biochemical aging column through a pipeline and is used for conveying an organic acid solution; the organic acid mixing device is provided with a second controller, and the second controller is used for receiving the pH value and the oxidation-reduction potential value of the soil of the field to be detected.
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