CN111924982A - A bio-permeable reaction wall in a compound polluted site and a preparation method thereof - Google Patents

Abstract

The invention discloses a biologically permeable reaction wall of a compound polluted site, comprising a concrete base, a concrete top cover, a reaction wall cavity and a reaction zone filler, wherein the reaction zone filler comprises bacillus phosphate solubilizing bacteria arranged in sequence along the seepage direction of groundwater The mineralized layer, the degraded layer of anaerobic bacillus and the degraded layer of aerobic bacillus; the mineralized layer of bacillus phosphate solubilization includes bacillus phosphate, the first quartz sand and phosphate rock powder; the degraded layer of anaerobic bacillus includes anaerobic bacillus Oxygen Bacillus, the second quartz sand and the first activated carbon; the aerobic bacillus degrading and interpreting oxygen layer includes aerobic bacillus, peroxide, the third quartz sand and the second activated carbon; it can realize the remediation and purification of heavy metal-organic compound pollution Strong ability; the service strength can be flexibly adjusted according to the change of pollution degree, and the life of the reaction wall can be increased; it can be used for the prevention and control of high-risk sudden pollution sites.

Description

A bio-permeable reaction wall in a compound polluted site and a preparation method thereof

technical field

The invention relates to the technical field of groundwater pollution remediation, in particular to a biologically permeable reaction wall of a compound polluted site and a preparation method thereof.

Background technique

In developing countries driven by industry, there are many complex situations such as multiple types of heavy metals, organic and compound pollution, and soil and water compound pollution. The existing methods of treating polluted groundwater include in-situ remediation and ex-situ remediation. The permeable reactive wall technology is a common in-situ treatment technology in groundwater remediation. It is constructed perpendicular to the direction in which the contaminated groundwater flows. Internal reactive materials remove contaminants from flowing groundwater. The permeable reaction wall has the advantages of continuous in-situ treatment of pollutants, treatment of various pollutants, small disturbance, good treatment effect, convenient installation and construction, and relatively high cost performance. At present, there have been many successful practical engineering examples in Europe and the United States. There are organic pollution sites and heavy metal pollution sites, but there are few permeable reaction walls that are highly efficient for organic-heavy metal compound pollution sites. In addition, the contaminated sites in the Yangtze and Yellow River basins in my country have the characteristics of complex geological and hydrological conditions, variable pollution levels, and sudden pollution sites. Therefore, the permeable reaction wall is not only required for the repair of existing polluted sites, but also urgently needs to meet the prevention and control of high-risk sudden pollution sites.

The reaction medium in the permeable reaction wall is either apatite, zeolite, slag, organophilic clay, biochar, etc. which are mainly adsorbed; or zero-valent iron with redox properties; or for pollutants in water Metabolic microorganisms. Among them, the microbial permeable reaction wall has good application prospects because of its remediation process without secondary pollution, low-carbon energy saving, and the ability to completely degrade organic pollutants.

However, the existing microbial permeable reaction walls have the following defects: poor remediation effect and weak purification ability for heavy metals and heavy metal-organic compound pollution; microbial nutrients in the permeable reaction walls are continuously consumed, so that the life of the reaction walls is short; microbial activity It is determined by the existing nutrient content of the reaction wall, and it is impossible to take suitable metabolic activities according to the degree of pollution. Therefore, for contaminated sites with variable pollution degrees, the restoration intensity cannot be flexibly adjusted according to the degree of pollution; once the microbial reaction wall is put in, the survival and metabolism of microorganisms will start. , can not meet the high-risk sudden pollution site prevention and control of the permeable reactive wall on standby requirements.

Therefore, how to prepare a permeable reactive wall that can purify heavy metal pollution, can flexibly adjust service strength according to the degree of pollution, and can meet the prevention and control of high-risk sudden pollution sites has become an urgent technical problem to be solved.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a bio-permeable reaction wall of a compound polluted site and a preparation method thereof, which can realize the remediation of heavy metal-organic compound pollution, has strong purification ability, can meet the requirements of high-risk sudden pollution sites, and can flexibly adjust the service intensity according to the degree of pollution.

In order to achieve the above object, the present invention provides a bio-permeable reaction wall of a compound polluted site, the permeable reaction wall includes a concrete base, a concrete top cover, a reaction wall cavity and a reaction zone filler, the concrete base and all The reaction wall cavity is arranged between the concrete top covers, and the reaction zone filler is arranged in the reaction wall cavity;

The reaction zone filler comprises a mineralization layer of Bacillus phosphate solubilization, a Bacillus anaerobic degrading layer and a Bacillus aerobic degrading layer which are arranged in sequence along the direction of groundwater seepage;

The raw materials of the Bacillus phosphate solubilizing layer include Bacillus phosphate solubilizing, the first quartz sand and phosphate rock powder;

The raw materials of the anaerobic bacillus degradation layer include anaerobic bacillus, the second quartz sand and the first activated carbon;

The raw materials of the aerobic bacillus degrading and explaining the oxygen layer include aerobic bacillus, peroxide, the third quartz sand and the second activated carbon.

Further, the phosphorus-solubilizing bacillus, the anaerobic bacillus and the aerobic bacillus have all been domesticated to use organic pollutants as the required carbon and nitrogen sources; The Bacillus and the aerobic Bacillus are purchased bacteria or selected from the contaminated site to be repaired.

Further, the particle sizes of the first quartz sand, the second quartz sand and the third quartz sand are all 0.1 mm to 3 mm; the particle sizes of the first activated carbon and the second activated carbon are both 0.05 mm mm～1mm.

Further, the thicknesses of the mineralized layer of Bacillus phosphate solubilization, the degraded layer of Bacillus anaerobes, and the degraded layer of Bacillus aerobic bacteria are all 30 cm to 40 cm.

Further, the preparation method of the mineralized layer of Bacillus phosphate solubilization is:

obtaining the Bacillus phosphate solubilization, the phosphate rock powder and the first quartz sand, and the Bacillus phosphate solubilization is a Bacillus phosphate solubilization suspension with an OD ₆₀₀ of 1.5-3;

Mixing and air-drying the Bacillus phosphate solubilizing bacteria and the phosphate rock powder in a mass-to-volume ratio of 1: (0.8-1.2) to obtain the phosphate rock powder loaded with the Bacillus phosphate solubilizing bacteria;

Mixing the phosphate rock powder loaded with Bacillus phosphate solubilization and the first quartz sand to obtain the Bacillus phosphate solubilization layer; wherein, the phosphate rock powder loaded with Bacillus phosphate solubilization and the The volume ratio of the first quartz sand is 1:(1-1.5).

Further, the preparation method of the anaerobic bacillus mineralized layer is:

obtaining the anaerobic bacillus, the first activated carbon and the second quartz sand, and the anaerobic bacillus is an anaerobic bacillus suspension with OD ₆₀₀ =1.5-3;

mixing and air-drying the anaerobic bacillus and the first activated carbon in a mass-to-volume ratio of 1: (0.8-1.2) to obtain the first activated carbon loaded with the anaerobic bacillus;

Mixing the second quartz sand and the first activated carbon loaded with anaerobic bacillus to obtain the mineralized layer of anaerobic bacillus; wherein, the first activated carbon loaded with anaerobic bacillus and the The volume ratio of the second quartz sand is 1:(1-1.5).

Further, the preparation method of the aerobic bacillus mineralized layer is:

obtaining the aerobic bacillus, the peroxide, the second activated carbon and the third quartz sand, and the aerobic bacillus is a suspension of the aerobic bacillus with OD ₆₀₀ =1.5-3;

Mixing and air-drying the aerobic bacillus and the second activated carbon in a mass-to-volume ratio of 1: (0.8-1.2) to obtain a second activated carbon loaded with the aerobic bacillus;

Mixing the peroxide, the third quartz sand and the second activated carbon loaded with aerobic bacillus to obtain the aerobic bacillus mineralized layer; wherein, the volume of the third quartz sand, the The volume ratio of the peroxide mass to the second activated carbon loaded with aerobic bacillus is (1-1.5):(0.4-0.7):1.

Further, the reaction wall cavity includes a first permeable concrete cavity, a second permeable concrete cavity and a third permeable concrete cavity; The oxygen-degrading and interpreting oxygen layers of bacillus oxygen are sequentially arranged in the first permeable concrete cavity, the second permeable concrete cavity and the third permeable concrete cavity.

Further, the wall thicknesses of the first permeable concrete cavity, the second permeable concrete cavity and the third permeable concrete cavity are all 15cm-25cm.

Further, the concrete base is provided with a slot, the slot includes a first slot, a second slot and a third slot, and the first permeable concrete cavity, the second permeable concrete cavity and the third slot. The three permeable concrete cavities are arranged on the first card slot, the second card slot and the third card slot in a one-to-one correspondence.

The present invention also provides a method for preparing the Bacillus microorganism permeable reaction wall prepared by the method, the method comprising:

obtaining a concrete base, and placing the concrete base horizontally;

A reaction wall cavity is obtained, a reaction zone filler is arranged in the reaction wall cavity, and the reaction wall cavity is arranged on the concrete base, and the reaction zone filler comprises a solution arranged in sequence along the groundwater seepage direction. Phosphorus bacillus mineralization layer, anaerobic bacillus degrading layer and aerobic bacillus degrading oxygen layer;

A concrete top cover is placed on the top of the reaction wall cavity.

One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

(1) A bio-permeable reaction wall of a compound polluted site provided by the present invention and a preparation method thereof, are composed of three layers of reaction media for repairing the dissolved phosphorus mineralization layer of heavy metals, anaerobic layer and aerobic layer for degrading organic pollutants, The three layers are layer by layer and progressive, through mineralization, adsorption, biodegradation, redox and other functions, heavy metal-organic composite pollutants in polluted groundwater can be efficiently removed. The free heavy metals in polluted groundwater are degraded by anaerobic bacillus and aerobic bacillus to realize the removal of heavy metal-organic composite pollution.

(2) Using the spore-producing dormancy characteristics of Bacillus, it can meet the requirements of the permeable reactive wall for standby service in the prevention and control of high-risk sudden pollution sites, and for contaminated sites with variable pollution levels, the service intensity can be flexibly adjusted according to the degree of pollution. , specifically: the permeable reactive wall screen is a Bacillus species that feeds on organic pollutants, and can produce spore dormancy when food is lacking. Therefore, when the permeable reaction wall is located in an uncontaminated high-risk compound contamination site or a compound contamination site with a reduced degree of groundwater pollution, Bacillus sp. gradually produces spore dormancy due to lack of food sources; At elevated concentrations, Bacillus reactivates and serves efficiently. Therefore, the Bacillus permeable reaction wall can flexibly serve in polluted sites with variable pollution levels, and can serve on standby in the face of uncontaminated high-risk sudden pollution sites to achieve the control effect. In addition, the microbial flora has strong adaptability to polluted environment and high reaction activity, and no additional nutrients are added to the reaction wall, which avoids rapid loss of the reaction medium, so the reaction wall has a long service life.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

Fig. 1 is the structural representation of a kind of compound polluted site biologically permeable reaction wall provided by the present invention;

2 is a flow chart of a method for preparing a bio-permeable reaction wall in a compound polluted site provided by the present invention;

1. Concrete base; 11. First slot; 12. Second slot; 13. Third slot; 2. Concrete top cover; 3. Reaction wall cavity; 31. First permeable concrete cavity; 32. The second permeable concrete cavity; 33, the third permeable concrete cavity; 4, the filler in the reaction zone; 41, the mineralized layer of Bacillus phosphate solubilization; 42, the degradation layer of anaerobic bacillus;

Detailed ways

The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly presented therefrom. It should be understood by those skilled in the art that these specific embodiments and examples are used to illustrate the present invention, but not to limit the present invention.

Throughout the specification, unless specifically stated otherwise, terms used herein are to be understood as commonly used in the art. Therefore, unless otherwise defined, 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. In case of conflict, the present specification takes precedence.

Unless otherwise specified, all kinds of raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or can be obtained by existing methods. In order to distinguish, the nouns such as "first" and "second" in the present invention do not represent the order, and can be understood as nouns.

The embodiment of the present invention provides a bio-permeable reaction wall of a compound polluted site, and the general idea is as follows:

According to a typical embodiment of the present invention, there is provided a bio-permeable reaction wall of a compound polluted site. As shown in FIG. 1 , the permeable reaction wall includes a concrete base 1, a concrete top cover 2 and a reaction zone filler 4, A reaction wall cavity 3 is arranged between the concrete base 1 and the concrete top cover 2, and the reaction zone filler is arranged in the reaction wall cavity 3;

The reaction zone filler 4 includes a Bacillus phosphate-solubilizing layer 41, a Bacillus anaerobic degrading layer 42 and a Bacillus aerobic degrading layer 43 that are sequentially arranged along the direction of groundwater seepage;

The raw materials of the Bacillus phosphate solubilizing layer 41 include Bacillus phosphate solubilizing, the first quartz sand and phosphate rock powder;

The raw materials of the anaerobic bacillus degrading layer 42 include anaerobic bacillus, the second quartz sand and the first activated carbon;

The raw materials of the aerobic bacillus degrading oxygen layer 43 include aerobic bacillus, peroxide, the third quartz sand and the second activated carbon.

The invention provides a bio-permeable reaction wall for a compound polluted site and a preparation method thereof. The layers are progressively laid, and the heavy metal-organic composite pollutants in the polluted groundwater can be efficiently removed through mineralization, adsorption, biodegradation, redox, etc.; Free heavy metals, use anaerobic bacillus and aerobic bacillus to degrade organic pollutants, realize the removal of heavy metal-organic composite pollution; use the spore-producing dormancy characteristics of bacillus, which can meet the requirements of high-risk sudden pollution site prevention and control of permeable The reaction wall is ready for service, and for contaminated sites with variable pollution levels, the service intensity can be flexibly adjusted according to the degree of pollution. Specifically: the permeable reaction wall screen is Bacillus that feeds on organic pollutants. Can produce spores during dormancy. Therefore, when the permeable reaction wall is located in an uncontaminated high-risk compound contamination site or a compound contamination site with a reduced degree of groundwater pollution, Bacillus sp. gradually produces spore dormancy due to lack of food sources; At elevated concentrations, Bacillus reactivates and serves efficiently. Therefore, the Bacillus permeable reaction wall can flexibly serve in polluted sites with variable pollution levels, and can serve on standby in the face of uncontaminated high-risk sudden pollution sites to achieve the control effect. In addition, the microbial flora has strong adaptability to polluted environment and high reaction activity, and no additional nutrients are added to the reaction wall, which avoids rapid loss of the reaction medium, so the reaction wall has a long service life.

Scheme 1: The phosphate-solubilizing bacillus, the anaerobic bacillus and the aerobic bacillus are all commercially available inoculants. Among them (1) Phosphorus soluble Bacillus: Bacillus subtilis, Bacillus megaterium, Bacillus colloid, Bacillus lateralis, Bacillus polymyxa and other three or more bacterial species in the genus Bacillus with phosphate solubilizing effect . (2) Anaerobic Bacillus: including three species of anaerobic Bacillus such as Clostridium butyricum, Clostridium perfringens, Clostridium difficile, Clostridium sporogenes, Clostridium botulinum, and Clostridium pasteurii Three or more bacterial species. (3) Aerobic Bacillus: Bacillus anthracis, Bacillus cereus, Bacillus subtilis, Bacillus mycoides, Bacillus polymyxa, Bacillus coagulans, Bacillus lateralis, Bacillus thuringiensis, Bacillus licheniformis, jelly Bacillus like Bacillus, Bacillus megaterium, Bacillus brevis, Bacillus lentus, Bacillus pumilus, Bacillus circulans, Bacillus firmus, Bacillus orientalis, Bacillus natto, Bacillus sporogenes and other aerobic Bacillus three kinds or Three or more bacterial species.

Scheme 2: All of the purchased Bacillus phosphate solubilization, Bacillus anaerobic Bacillus and Bacillus aerobic Bacillus are domesticated to use organic pollutants as the required carbon source and nitrogen source, specifically: the purchased Bacillus phosphate solubilization , Anaerobic Bacillus and aerobic Bacillus were cultivated with the medium and culture method recommended in the purchase instructions of the preservation center, and gradually replaced the nutrient components with the groundwater of the contaminated site, and at the same time, the concentration of the groundwater of the contaminated site was continuously increased; Bacillus surviving in the triplicate medium was isolated, preserved or expanded. In this scheme, the final surviving purchased Bacillus phosphate, Bacillus anaerobic and Bacillus aerobic can be adapted to the harsh environment of the contaminated site faster when applied, and the expression of the genes that feed on the organic pollutants of the contaminated site can be expressed more efficiently. powerful.

Option 3: Screen out the Phosphorus solubilizing Bacillus, the Anaerobic Bacillus and the Aerobic Bacillus in the polluted site to be rehabilitated, and all of them are domesticated to use organic pollutants as the required carbon and nitrogen sources. The specific preparation method is:

Step 1. Collect multiple soil samples within the contamination plume range of the contaminated site as a bacterial source;

Step 2. Fully mix the collected soil samples and divide them into three parts, respectively carry out phosphorus-dissolving culture, anaerobic culture and aerobic culture, and screen out Bacillus spp. from the three cultured microflora; the details are as follows:

(1) Phosphorus-soluble enrichment culture

①Preparation of inorganic phosphorus bacterial culture medium: glucose 10.0g, (NH ₄ ) ₂ SO ₄ 0.5g, NaCl 0.3g, KCl 0.3g, MgSO ₄ ·7H ₂ O 0.3g, FeSO ₄ ·7H ₂ O 0.03g, MnSO ₄ 1.0 g, Ca ₃ [PO ₄ ] ₂ 5.0 g, H ₂ O 1000 mL, agar 15 g

②Preparation of organophosphorus bacteria medium: glucose 10.0g, (NH ₄ ) ₂ SO ₄ 0.5g, NaCl 0.3g, KCl 0.3g, MgSO ₄ ·7H ₂ O 0.3g, FeSO ₄ ·7H ₂ O 0.03g, MnSO ₄ 1.0g, lecithin 5.0g, H ₂ O 1000mL, CaO 20g, agar 15g;

③ Screening of Phosphorus-Solubilizing Bacteria: The collected soil samples were spread on the above-mentioned two mediums by the dilution plate method, cultured at 30°C for 3 days, and the single colony that produced a transparent circle around the medium was selected for streak purification and stored in LB solid. on the slanted medium.

④Isolation and identification of Bacillus phosphate solubilization: The 16S rRNA/rDNA sequence analysis method was used to isolate and identify the screened Bacillus, so as to obtain Bacillus phosphate solubilization with organic pollutants as carbon and nitrogen sources for bacterial life .

(2) Anaerobic enrichment culture

①Prepare common solid medium plates (such as LB/NA/NB, etc.);

② Coat the collected soil samples on the culture medium plate by the dilution plate method, put the plate into an anaerobic bag, put it in an oxygen absorber, seal the mouth, and cultivate it in an ordinary incubator for 3 days;

③Bacillus was isolated and identified by using 16S rRNA/rDNA sequence analysis method to grow the single colony.

(3) Aerobic enrichment culture

①Prepare common solid medium plates (such as LB/NA/NB, etc.);

② Coat the collected soil samples on the medium plate by the dilution plate method, and put the plate into a common incubator for 3 days;

③Bacillus was isolated and identified by using 16S rRNA/rDNA sequence analysis method to grow the single colony.

It should be noted that, since Bacillus is very common in nature, the microorganism must be able to be obtained according to the above-mentioned screening and domestication method, and it is not accidental.

Step 3. Gradually replace the nutrients in the three mediums with the groundwater of the polluted site, and continuously increase the concentration of the groundwater of the polluted site;

Step 4. Separate, preserve or expand the Bacillus surviving in the three mediums.

The Phosphorolytic Bacillus, the Anaerobic Bacillus and the Aerobic Bacillus were all screened from the contaminated site to be rehabilitated and were domesticated because: (1) the native bacteria in the site are more adaptable to the polluted environment; (2) The native Bacillus species in the site all have the ability to feed on the organic matter in the contaminated site; (3) Further domestication makes the gene expression of the native Bacillus in the site to feed on the organic pollutants in the contaminated site stronger.

As a preferred embodiment, the reaction wall cavity 3 includes a first permeable concrete cavity 31, a second permeable concrete cavity 32 and a third permeable concrete cavity 33; The bacillus degrading layer 42 and the aerobic bacillus degrading and deoxidizing layer 43 are sequentially arranged in the first permeable concrete cavity 31 , the second permeable concrete cavity 32 and the third permeable concrete cavity 33 .

As a preferred embodiment, the wall thicknesses of the first permeable concrete cavity, the second permeable concrete cavity and the third permeable concrete cavity are all 15 cm to 25 cm. The thickness needs to ensure that the permeable concrete cavity of a certain height has sufficient strength and is not easy to bend, deform or break. The greater the height of the permeable concrete cavity, the greater the required wall thickness of the permeable concrete cavity. Among them, the height of the permeable concrete cavity should be determined according to the specific geological and hydrological conditions. The bottom end of the permeable concrete cavity is embedded in an impermeable layer of at least 160cm to prevent the bottom seepage of the pollution plume from flowing to the downstream area, and the top must be higher than the maximum water level of the groundwater.

The permeable speed of the first permeable concrete cavity, the second permeable concrete cavity and the third permeable concrete cavity is 30-50L/m/h. The permeable speed here emphasizes the permeable performance of the permeable concrete itself. , which requires permeable concrete with permeable performance in this parameter range as the cavity. In addition, the specific determination of this parameter depends on the nature of the soil layer of the contaminated site, the stronger the permeability of the soil layer of the site (sand > silty sand > sandy silt > silt > clay silt > silty clay > clay) ), the water permeability of the selected pervious concrete is larger within this range.

As a preferred embodiment, the thicknesses of the mineralized layer of Bacillus phosphate solubilization, the degraded layer of Bacillus anaerobes and the degraded layer of Bacillus aerobic bacteria are all 30cm-40cm. The thickness range is based on the common groundwater flow velocity of the polluted site and the hydraulic retention time of the common concentration of pollutants in the permeable reaction wall of the present invention, that is, the reaction time required to repair the pollutants, that is, the residence time of the pollution plume in the reaction wall time design. Within this thickness range, it follows the law that the thickness increases with the concentration of pollutants. Each layer of media corresponds to different pollutant objects to be repaired, and the thickness of each layer is determined according to the corresponding pollutant concentration. For a certain concentration of pollutants, if the reaction medium layer is too thin, the target reaction effect will not be achieved, and if the reaction medium layer is too thick, the reaction effect will not be improved, which will increase the cost and low cost performance.

The compaction degree, also known as the compaction degree, refers to the ratio of the compacted dry density of soil or other road construction materials to the standard maximum dry density, expressed as a percentage. After each layer of reaction material is prepared in proportion, it is filled into the cavity according to the designed compaction degree. When the packing compaction degree is low, the reaction medium is loose and the penetration is strong; when the packing compaction degree is high, the reaction medium is dense, and the permeability decreases when the packing compaction degree is relatively loose. In actual operation, the degree of compaction should be determined according to the permeability of the site soil, and it is sufficient to ensure that the permeability of the reaction medium of each layer is slightly greater than that of the contaminated soil of the site.

As a preferred embodiment, the concrete base 1 is provided with a slot, the slot includes a first slot 11, a second slot 12 and a third slot 13, and the first permeable concrete cavity 31 , The second permeable concrete cavity 32 and the third permeable concrete cavity 33 are arranged on the first clamping slot 11 , the second clamping slot 12 and the third clamping slot 13 in a one-to-one correspondence.

The concrete base is C30 ordinary concrete, and the height is preferably 30cm to 50cm; the shapes of the first permeable concrete cavity 31, the second permeable concrete cavity 32 and the third permeable concrete cavity 33 are preferably U-shaped; the present invention is permeable The reactant medium of each layer of the reaction wall is carried by independent U-shaped permeable concrete, which has the advantages of draining groundwater, preventing the deformation of the reaction wall system, avoiding the loss and mutual interference of the reactant medium of each layer, convenient disassembly and assembly, light weight and low cost;

The heights of the first card slot 11 , the second card slot 12 and the third card slot 13 are all 20cm to 35cm, and this height is conducive to the separation of the first permeable concrete cavity 31 , the second permeable concrete cavity 32 and the third The permeable concrete cavity 33 is clamped tightly.

The shapes of the first slot 11 , the second slot 12 and the third slot 13 correspond to the bottom shapes of the first permeable concrete cavity 31 , the second permeable concrete cavity 32 and the third permeable concrete cavity 33 respectively. ; The shape of the first card slot 11, the second card slot 12 and the third card slot 13 is preferably U-shaped; the width of the card slot depends on the width of the permeable concrete cavity placed;

The concrete roof 12 is made of C30 ordinary concrete, the thickness of the roof is 10cm-15cm, and the inner width of the roof depends on the total width of the permeable reaction wall.

As a preferred embodiment, the preparation method of the mineralized layer of Bacillus phosphate solubilization is:

obtaining the Bacillus phosphate solubilization, the phosphate rock powder and the first quartz sand, and the Bacillus phosphate solubilization is a Bacillus phosphate solubilization suspension with an OD ₆₀₀ of 1.5-3;

Mixing and air-drying the Bacillus phosphate solubilizing bacteria and the phosphate rock powder in a mass-to-volume ratio of 1: (0.8-1.2) to obtain the phosphate rock powder loaded with the Bacillus phosphate solubilizing bacteria;

Mixing the phosphate rock powder loaded with Bacillus phosphate solubilization and the first quartz sand to obtain the Bacillus phosphate solubilization layer; wherein, the phosphate rock powder loaded with Bacillus phosphate solubilization and the The volume ratio of the first quartz sand is 1:(1-1.5).

The reasons why the phosphate rock powder is used as a Bacillus phosphate solubilizer are: 1) the phosphate rock powder itself has adsorption properties and can immobilize bacteria on its surface; 2) the phosphate rock powder dissolves insoluble phosphate rock by secreting organic acids 3) Phosphate rock powder also has good adsorption, complexation and ion exchange effects on heavy metals, which can further enhance the removal effect of Bacillus phosphate solubilizing layer on heavy metals.

The reason for mixing the phosphate rock powder loaded with Bacillus phosphate solubilization and the first quartz sand is: because of its larger particle size, quartz sand is used as coarse aggregate in the reaction medium to ensure that the reaction medium has better performance. permeability.

The reason for selecting the Bacillus phosphate solubilizing Bacillus phosphate solubilization suspension with OD ₆₀₀ =1.5-3 is: OD ₆₀₀ is the absorbance value of the bacterial suspension at a wavelength of 600 nm, and its value represents the concentration of the bacterial suspension. When microorganisms/bacteria treat the environment, the bacterial suspension with this range of concentration is often used, and the value selected within this range increases with the greater the concentration of the corresponding remediation pollutants.

The reason why the mass-to-volume ratio of the phosphate-solubilizing bacillus and the phosphate rock powder is 1: (0.8-1.2) is: this value is a better ratio found by experiments, and if the ratio is too small, it will lead to dissolved phosphorus in the reaction medium. The number of Bacillus is insufficient, and the repair reaction period is long; if the value is too large, the effect will not be improved, and the cost will increase and the cost performance will be low.

The reason why the volume ratio of the phosphate rock powder loaded with Bacillus phosphate solubilization to the first quartz sand is 1: (1-1.5) is that this value is a better ratio found through experiments, and if it is too small, it will lead to reaction substances Insufficient, the repair effect is poor; if the value is too large, the repair effect is not improved, and the cost performance is low; according to the pollutant concentration, within this range, the higher the pollution degree, the greater the ratio.

As a preferred embodiment, the preparation method of the anaerobic bacillus mineralized layer is:

obtaining the anaerobic bacillus, the first activated carbon and the second quartz sand, and the anaerobic bacillus is an anaerobic bacillus suspension with OD ₆₀₀ =1.5-3;

mixing and air-drying the anaerobic bacillus and the first activated carbon in a mass-to-volume ratio of 1: (0.8-1.2) to obtain the first activated carbon loaded with the anaerobic bacillus;

Mixing the second quartz sand and the first activated carbon loaded with anaerobic bacillus to obtain the mineralized layer of anaerobic bacillus; wherein, the first activated carbon loaded with anaerobic bacillus and the The volume ratio of the second quartz sand is 1:(1-1.5).

The reason for selecting the anaerobic bacillus suspension with OD ₆₀₀ = 1.5 to 3 for the anaerobic bacillus is: OD 600 is the absorbance value of the bacterial suspension at a wavelength of 600 nm, and its value represents the concentration of the bacterial suspension. When microorganisms/bacteria remediate the environment, it is generally this range or lower, and the value selected within this range increases with the greater the concentration of the corresponding remediation pollutants.

The reason why the mass-to-volume ratio of the anaerobic bacillus and the first activated carbon is 1:(0.8-1.2) is: this value is a better ratio found by experiments, and if the ratio is too small, the content of microorganisms in the initial stage of restoration will be insufficient. , the initial repair effect is poor, and it takes a period of time to reproduce the required microbial content to achieve the target effect; if the value is too large, the effect will not be improved, and the cost will increase, the cost performance is low,

The reason why the volume ratio of the second quartz sand and the first activated carbon is 1:(1-1.5) is: this value is a better ratio found by experiments, and if it is too large, it will lead to insufficient reaction substances and poor repairing effect; If the value is too small, the effect will not be improved, and the cost performance is not high; according to the concentration of pollutants, within this range, the higher the pollution degree, the smaller the ratio.

As a preferred embodiment, the preparation method of the aerobic bacillus degrading oxygen layer is:

obtaining the aerobic bacillus, the peroxide, the second activated carbon and the third quartz sand, and the aerobic bacillus is a suspension of the aerobic bacillus with OD ₆₀₀ =1.5-3;

Mixing and air-drying the aerobic bacillus and the second activated carbon in a mass-to-volume ratio of 1: (0.8-1.2) to obtain a second activated carbon loaded with the aerobic bacillus;

Mixing the peroxide, the third quartz sand and the second activated carbon loaded with aerobic bacillus to obtain the aerobic bacillus mineralized layer; wherein, the volume of the third quartz sand, the The volume ratio of the peroxide mass to the second activated carbon loaded with aerobic bacillus is (1-1.5):(0.4-0.7):1.

The mineralized layer of Bacillus phosphate solubilization selects phosphate rock powder as the carrier; and the anaerobic Bacillus degraded layer selects activated carbon (instead of rock phosphate powder) as the carrier, and the aerobic Bacillus degrading layer selects the phosphate rock as the carrier. The reason why activated carbon (instead of phosphate rock powder) is used as a carrier is: because the restoration objects of the anaerobic bacillus degraded layer and the aerobic bacillus degraded oxygen layer are organic pollutants, biochar has a better adsorption effect on organic pollutants , which can further enhance the removal effect of the reaction layer on organic pollutants. Although phosphate rock powder can be used as a bacterial carrier, it has no effect on organic pollutants and has no additional effect here, so biochar is selected.

The reason why the volume ratio of the third quartz sand, the mass of the peroxide, and the second activated carbon is (1-1.5): (0.4-0.7): 1 is that this value is a better ratio found through experiments ; The peroxide can be specifically selected from MgO ₂ , CaO ₂ , etc., which can react with water to release oxygen. If there are too many peroxides, too much oxygen will block the circulation of polluted groundwater in the aerobic layer, which will reduce the repair efficiency of the permeable reaction wall. If the amount of peroxide is too small, the oxygen production will be insufficient, and the repair effect of aerobic microorganisms in this layer will be poor.

The reason why the volume ratio of the third quartz sand and the second activated carbon is 1:(1-1.5) is: this value is a better ratio found by experiments, and if it is too large, it will lead to insufficient reactive substances and poor repairing effect; If the value is too small, the effect will not be improved, and the cost performance is not high; according to the concentration of pollutants, within this range, the higher the pollution degree, the smaller the ratio.

As a preferred embodiment, the particle sizes of the first quartz sand, the second quartz sand and the third quartz sand are all 0.1 mm to 3 mm; the quartz sand within this range is used as the permeable reaction wall of the present invention When the coarse aggregate of the medium reaction medium is used, the reaction medium has moderate water permeability, which is larger than that of the surrounding site soil, which can guide the inflow of groundwater, and at the same time ensure that the polluted groundwater can fully stay and react in it, so as not to flow away too quickly.

The particle sizes of the first activated carbon and the second activated carbon are both 0.05 mm to 1 mm. The selection of this range is the best range found by experiments. As the particle size increases, the adsorption effect of activated carbon decreases.

It should be noted that the particle size ranges of the first quartz sand, the second quartz sand, the third quartz sand, the first activated carbon and the second activated carbon are not intended to be determined within the range. value, and it means that the first quartz sand, the second quartz sand, the third quartz sand, the first activated carbon or the second activated carbon can have different particle sizes, as long as they are within the range.

According to another typical embodiment of the present invention, there is provided a method for preparing a bio-permeable reaction wall in a compound polluted site, as shown in FIG. 2 , the method includes:

S1, obtaining a concrete base, and placing the concrete base horizontally;

S2. Obtain a reaction wall cavity, set the reaction zone filler in the reaction wall cavity, and set the reaction wall cavity on the concrete base, and the reaction zone filler includes sequentially arranged along the groundwater seepage direction The mineralized layer of Bacillus phosphate dissolved, the degraded layer of anaerobic Bacillus and the degraded oxygen layer of Bacillus aerobic;

S3, setting a concrete top cover on the top of the reaction wall cavity.

Specifically, the concrete base in S1 is provided with the first card slot 11 , the second card slot 12 and the third card slot 13 ;

Specifically, the reaction wall cavity in S2 includes a first permeable concrete cavity 31 , a second permeable concrete cavity 32 and a third permeable concrete cavity 33 ; the first permeable concrete cavity 31 and the second permeable concrete cavity 32 One-to-one correspondence with the third permeable concrete cavity 33 is provided on the first card slot 11 , the second card slot 12 and the third card slot 13 .

The present invention adopts Bacillus genus that feeds on organic pollutants screened from the polluted site as the reaction microorganism. The microbial flora has strong adaptability to the polluted environment and high reaction activity, and no additional nutrients are added to the reaction wall, thereby avoiding the need for The reaction medium is rapidly depleted, so the reaction wall has a long service life. In addition, Bacillus is used as the reaction microorganism, and its spore-producing dormancy characteristics can be used to achieve elastic restoration for contaminated sites with variable pollution levels, and for high-risk sudden pollution sites. Standby prevention.

The bio-permeable reaction wall of a compound polluted site of the present application will be described in detail below with reference to the examples, comparative examples and experimental data.

S1, obtaining the concrete base 1, and placing the concrete base 1 horizontally, in the S1, the concrete base is provided with the first card slot 11, the second card slot 12 and the third card slot 13;

S2. Obtain a reaction wall cavity 3, the reaction wall cavity includes a first permeable concrete cavity 31, a second permeable concrete cavity 32 and a third permeable concrete cavity 33; the first permeable concrete cavity, the second permeable concrete cavity The wall thicknesses of the concrete cavity and the third permeable concrete cavity are shown in Table 1.

The reaction zone filler is arranged in the reaction wall cavity 3, and the reaction wall cavity 3 is arranged on the concrete base 1, and the reaction zone filler 4 includes dissolved phosphorus sequentially arranged along the direction of groundwater seepage. Bacillus mineralization layer 41, anaerobic bacillus degrading layer 42 and aerobic bacillus degrading layer 43; The deoxidizing layer is sequentially arranged in the first permeable concrete cavity, the second permeable concrete cavity and the third permeable concrete cavity.

The raw materials of the Bacillus phosphate solubilizing layer include Bacillus phosphate solubilizing, the first quartz sand and phosphate rock powder;

The raw materials of the anaerobic bacillus degradation layer include anaerobic bacillus, the second quartz sand and the first activated carbon;

The raw materials of the aerobic bacillus degrading and deciphering the oxygen layer include aerobic bacillus, peroxide, the third quartz sand and the second activated carbon; wherein the phosphorus solubilizing bacillus, the anaerobic bacillus and the aerobic bacillus Bacillus bacteria were all screened from contaminated sites to be rehabilitated, and were domesticated to use organic pollutants as the required carbon and nitrogen sources.

Wherein, the thickness and compaction degree of the mineralized layer of Bacillus phosphate solubilization, the degraded layer of Bacillus anaerobic, the degraded layer of Bacillus aerobic bacteria and the degree of compaction are shown in Table 2, and the material ratio between the shown raw materials is shown in Table 2. 3 shown.

S3, setting a concrete top cover on the top of the reaction wall cavity.

Wherein, the permeable reaction wall in Example 1 is applied to a heavy metal-organic composite pollution site with prominent heavy metal pollution and serious pollution.

In Example 2, the permeable reaction wall was applied to a heavy metal-organic composite pollution site with prominent organic pollution and serious pollution, and the polluted soil layer was sandy silt. According to the underground hydrology, the cavity height was set to 5m;

In Example 3, the permeable reaction wall was applied to a heavy metal-organic composite pollution site with serious heavy metal and organic pollution. The polluted soil layer was silty sand, and the cavity height was set to 4m.

Table 1

Table 2

table 3

The remediation effects of the permeable reaction walls prepared in each example and each comparative example in the polluted site are as follows, and the analysis results are shown in Table 4.

Table 4

It can be seen from the data in Table 4 that:

In Comparative Example 1, the mass-to-volume ratio of the Bacillus to the carrier was 0.5:1.2, which was less than the ratio of the present invention, and the rest were the same as in Example 1. Ⅱ) The removal effect is 80%, the repair rate for COD is only 69%, the repair rate for BOD is only 85%, and the repair effect is not good;

In Comparative Example 2, the ratio of the mass of the apatite ore powder attached to Bacillus phosphate solubilization to the volume of the first quartz sand, the mass of the first activated carbon loaded with the anaerobic Bacillus and the volume of the second quartz sand are all 0.5:1, which is less than 0.5:1. The ratio of the present invention, the rest are the same as in Example 1, the removal effect of Pb(II) is 74%, the repair rate of COD is only 71%, and the repair effect is not good;

In Comparative Example 3, the volume ratio of the third quartz sand, the mass of peroxide and the second activated carbon loaded with aerobic bacillus is 1.5:0.3:1, the percentage of peroxide is too small compared to the present invention, and the rest are Same as Example 1, the repair rate of COD is only 75%, the repair rate of BOD is only 77%, and the repair effect is not good;

In Comparative Example 4, the thicknesses of the mineralized layer of Bacillus phosphate solubilization, the degraded layer of Bacillus anaerobes, and the degraded layer of Bacillus aerobic bacteria are all 25 cm, which is less than the range of 30 cm to 40 cm in the present invention. The repair rate of Pb(II) is 83%, the repair rate of Zn(II) is 84%, the repair rate of Cu(II) is 79%, the repair rate of COD is only 78.7%, and the repair rate of BOD Only 85%, the repair effect is not good;

The permeable reaction walls of Bacillus microorganisms prepared in Examples 1 to 3 of the present invention have a good repair effect, and the repair rates of Pb(II), Zn(II), Cu(II), COD, and BOD are all 99%. Above, the purification ability is strong, and it can meet the high-risk sudden pollution site, and the service intensity can be flexibly adjusted according to the pollution degree.

To sum up, it is composed of three layers of reaction media: the dissolved phosphorus mineralization layer for repairing heavy metals, the anaerobic layer and the aerobic layer for degrading organic pollutants. Reduction and other effects can effectively remove heavy metal-organic composite pollutants in polluted groundwater; and by utilizing the dormant characteristics of Bacillus sp., it can meet the requirements for the standby service of permeable reaction walls in the prevention and control of high-risk sudden pollution sites, and has a significant impact on the degree of pollution. The service intensity can be flexibly adjusted according to the pollution degree in the changeable pollution site.

The proportion of each component in the anaerobic layer and the aerobic layer that degrades organic pollutants by further controlling the phosphorus-dissolving mineralization layer, lack of any component, or the content is not within the range, can not obtain spores with good performance Microorganisms of the genus Bacillus permeate the reaction wall.

Finally, it should also be noted that the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device comprising a series of elements includes not only those elements, but also Also included are other elements not expressly listed or inherent to such a process, method, article or apparatus.

Although preferred embodiments of the present invention have been described, additional changes and modifications to these embodiments may occur to those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be construed to include the preferred embodiment and all changes and modifications that fall within the scope of the present invention.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Thus, provided that these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims (10)

1. a composite pollution site biological permeable reaction wall, is characterized in that, described permeable reaction wall comprises concrete base, concrete top cover, reaction wall cavity and reaction zone filler, described concrete base and described concrete The reaction wall cavity is arranged between the top covers, and the reaction zone filler is arranged in the reaction wall cavity; The reaction zone filler comprises a mineralization layer of Bacillus phosphate solubilization, a Bacillus anaerobic degrading layer and a Bacillus aerobic degrading layer which are arranged in sequence along the direction of groundwater seepage; The raw materials of the Bacillus phosphate solubilizing layer include Bacillus phosphate solubilizing, the first quartz sand and phosphate rock powder; The raw materials of the anaerobic bacillus degradation layer include anaerobic bacillus, the second quartz sand and the first activated carbon; The raw materials of the aerobic bacillus degrading and explaining the oxygen layer include aerobic bacillus, peroxide, the third quartz sand and the second activated carbon. 2. a kind of compound pollution site biopermeable reaction wall according to claim 1, is characterized in that, described Phosphorolytic Bacillus, described anaerobic Bacillus and described aerobic Bacillus are all acclimated to organic pollution The required carbon and nitrogen sources are the required carbon and nitrogen sources; the phosphorus-solubilizing bacillus, the anaerobic bacillus and the aerobic bacillus are purchased bacteria or screened from contaminated sites. 3. The biologically permeable reaction wall of a compound polluted site according to claim 1, wherein the particle sizes of the first quartz sand, the second quartz sand and the third quartz sand are all 0.1 mm˜3 mm; the particle sizes of the first activated carbon and the second activated carbon are both 0.05 mm˜1 mm. 4. a kind of compound pollution site biopermeable reaction wall according to claim 1 is characterized in that, described phosphorolytic bacillus mineralization layer, described anaerobic bacillus degraded layer and described aerobic bacillus degraded layer. Explain that the thickness of the oxygen layer is 30cm ~ 40cm. 5. a kind of compound pollution site biopermeable reaction wall according to claim 1, is characterized in that, the preparation method of described Bacillus phosphate solubilization mineralization layer is: obtaining the Bacillus phosphate solubilization, the phosphate rock powder and the first quartz sand, and the Bacillus phosphate solubilization is a Bacillus phosphate solubilization suspension with an OD ₆₀₀ of 1.5-3; Mixing and air-drying the Bacillus phosphate solubilizing bacteria and the phosphate rock powder in a mass-to-volume ratio of 1: (0.8-1.2) to obtain the phosphate rock powder loaded with the Bacillus phosphate solubilizing bacteria; Mixing the phosphate rock powder loaded with Bacillus phosphate solubilization and the first quartz sand to obtain the Bacillus phosphate solubilization layer; wherein, the phosphate rock powder loaded with Bacillus phosphate solubilization and the The volume ratio of the first quartz sand is 1:(1-1.5). 6. a kind of compound pollution site bio-permeable reaction wall according to claim 1, is characterized in that, the preparation method of described anaerobic bacillus mineralized layer is: obtaining the anaerobic bacillus, the first activated carbon and the second quartz sand, and the anaerobic bacillus is an anaerobic bacillus suspension with OD ₆₀₀ =1.5-3; mixing and air-drying the anaerobic bacillus and the first activated carbon in a mass-to-volume ratio of 1: (0.8-1.2) to obtain the first activated carbon loaded with the anaerobic bacillus; Mixing the second quartz sand and the first activated carbon loaded with anaerobic bacillus to obtain the mineralized layer of anaerobic bacillus; wherein, the first activated carbon loaded with anaerobic bacillus and the The volume ratio of the second quartz sand is 1:(1-1.5). 7. a kind of compound pollution site bio-permeable reaction wall according to claim 1, is characterized in that, the preparation method of described aerobic bacillus mineralization layer is: obtaining the aerobic bacillus, the peroxide, the second activated carbon and the third quartz sand, and the aerobic bacillus is a suspension of the aerobic bacillus with OD ₆₀₀ =1.5-3; Mixing and air-drying the aerobic bacillus and the second activated carbon in a mass-to-volume ratio of 1: (0.8-1.2) to obtain a second activated carbon loaded with the aerobic bacillus; Mixing the peroxide, the third quartz sand and the second activated carbon loaded with aerobic bacillus to obtain the aerobic bacillus mineralized layer; wherein, the volume of the third quartz sand, the The volume ratio of the peroxide mass to the second activated carbon loaded with aerobic bacillus is (1-1.5):(0.4-0.7):1. 8 . The bio-permeable reaction wall of a compound polluted site according to claim 1 , wherein the reaction wall cavity comprises a first permeable concrete cavity, a second permeable concrete cavity and a third permeable concrete cavity; The mineralized layer of Bacillus phosphate solubilization, the degraded layer of Bacillus anaerobic and the degraded layer of Bacillus aerobic bacteria are sequentially arranged in the first permeable concrete cavity, the second permeable concrete cavity and the third permeable concrete cavity Inside. 9 . The bio-permeable reaction wall of a composite polluted site according to claim 8 , wherein the wall thickness of the first permeable concrete cavity, the second permeable concrete cavity and the third permeable concrete cavity are 15cm-25cm; the concrete base is provided with a slot, the slot includes a first slot, a second slot and a third slot, and the first permeable concrete cavity, the second permeable concrete cavity The cavity and the third permeable concrete cavity are arranged on the first card slot, the second card slot and the third card slot in a one-to-one correspondence. 10. A method for preparing the bio-permeable reaction wall of any one of claims 1-9, wherein the method comprises: obtaining a concrete base, and placing the concrete base horizontally; A reaction wall cavity is obtained, a reaction zone filler is arranged in the reaction wall cavity, and the reaction wall cavity is arranged on the concrete base, and the reaction zone filler comprises a solution arranged in sequence along the groundwater seepage direction. Phosphorus bacillus mineralization layer, anaerobic bacillus degrading layer and aerobic bacillus degrading oxygen layer; A concrete top cover is placed on the top of the reaction wall cavity.

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