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CN114249507A - Based on Fe0Composite permeable reactive barrier system of bentonite modified biochar filler and application thereof - Google Patents

Based on Fe0Composite permeable reactive barrier system of bentonite modified biochar filler and application thereof Download PDF

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CN114249507A
CN114249507A CN202210048918.8A CN202210048918A CN114249507A CN 114249507 A CN114249507 A CN 114249507A CN 202210048918 A CN202210048918 A CN 202210048918A CN 114249507 A CN114249507 A CN 114249507A
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bentonite
bentonite modified
biochar
quartz sand
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张满成
刘翠翠
王海鑫
潘月
辜建强
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Jiangsu Provincial Academy of Environmental Science
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    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F1/001Processes for the treatment of water whereby the filtration technique is of importance
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/28Treatment of water, waste water, or sewage by sorption
    • C02F1/281Treatment of water, waste water, or sewage by sorption using inorganic sorbents
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/70Treatment of water, waste water, or sewage by reduction
    • C02F1/705Reduction by metals
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    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00Nature of the contaminant
    • C02F2101/10Inorganic compounds
    • C02F2101/16Nitrogen compounds, e.g. ammonia
    • C02F2101/163Nitrates
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00Nature of the contaminant
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    • C02F2101/36Organic compounds containing halogen
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    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F2103/06Contaminated groundwater or leachate
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    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00Biological treatment of water, waste water, or sewage
    • C02F3/34Biological treatment of water, waste water, or sewage characterised by the microorganisms used

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Abstract

The invention discloses a Fe-based alloy0The composite permeable reactive barrier system of bentonite modified biochar filler and application thereof are characterized in that a quartz sand water inlet layer and Fe are sequentially arranged on the composite permeable reactive barrier system0-a bentonite modified biochar layer, a resin layer and a quartz sand effluent layer; wherein, the Fe0An injection well is arranged in the bentonite modified charcoal layer, and the other part is filled with Fe loaded with microorganisms0-bentonite modified biochar and quartz sand. The composite permeable reactive barrier can realize the efficient and durable removal of chlorinated organic compounds and nitrates in underground water, has no secondary pollution of degradation byproducts, and has long service lifeHas long service life and wide application prospect in the field of groundwater pollution remediation.

Description

Based on Fe0Composite permeable reactive barrier system of bentonite modified biochar filler and application thereof
Technical Field
The invention relates to the technical field of groundwater remediation, in particular to a Fe-based iron core0A composite permeable reactive barrier system of bentonite modified biochar filler and application thereof.
Background
Investigation of groundwater contamination in the United states showed that a groundwater sample contained 44% volatile organics and 28% nitrates. Research reports show that the detection rate of organic pollutants in 69 urban underground waters in China is 48.42% high, wherein chlorinated organic matters are main organic pollution components. In addition, research reports show that the exceeding rate of the nitrate of underground water in the northeast black soil area is as high as 39.6%, the exceeding rate of the northwest tidal soil area is 19.3%, and the exceeding rate of the northwest brown soil area is 14.9%. Therefore, the pollution of chlorinated organic matters and nitrates in the underground water is quite serious, and the pollution poses serious threats to the health of human bodies. Chlorinated organic compounds such as chloronitrobenzene in groundwater have a 'three-cause' effect, can enter organisms through skin absorption, respiration, food intake and the like, and accumulate, so that various diseases are caused, and organs are cancerated. High concentrations of nitrate in groundwater can damage human health, leading to methemoglobinemia and gastric cancer, among others. The nitrate can generate nitrosamine and nitrosamide with 'three-cause' effect after reaction, and seriously threatens the health of human beings, animals and plants.
The Permeable Reactive Barrier (PRB) technology is a groundwater in-situ remediation technology which is favored by people in recent years, and has the advantages of simple engineering facilities, low manufacturing cost, small influence on ecological environment, no need of additional power, low operation and maintenance cost and the like. The PRB technology is utilized to remove chlorinated organic compounds and nitrate compound pollutants in underground water, and the most important is the selection and research and development of reaction media. Maojianzhong and the like utilize Pt/C catalyst to carry out hydrogenation reduction on o-chloronitrobenzene, and the obtained degradation product is mainly o-chloroaniline; sun Yi et al are based on Ni-B/SiO2The amorphous alloy catalyst catalyzes the hydrogenation of o-chloronitrobenzene to degrade the product 98.2% is o-chloroaniline; the o-chloronitrobenzene is reduced by adopting a Pt/CNTs catalyst in a glowing state, and 99.8 percent of the o-chloronitrobenzene is converted into o-chloroaniline. Studies report that the byproduct o-chloroaniline is extremely toxic, and is poisoned by skin absorption, vapor inhalation or swallowing, and bladder cancer can be caused, resulting in kidney and liver damage. Westerhoff treats nitrate nitrogen with zero-valent iron, and only reduces the concentration of nitrate nitrogen from 90mg/L to below 10 mg/L. In addition, researches show that byproducts such as nitrite and ammonium ions generated in the nitrate removal process can cause secondary pollution to the underground water environment, and the human health is seriously harmed.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to solve the technical problem of providing the Fe loaded with the microorganisms aiming at the defects of the prior art0A preparation method of bentonite modified biochar.
The invention also aims to solve the technical problem of providing a Fe-based alloy0-bentonite modified biochar filler composite permeable reactive barrier system.
The technical problem to be solved by the invention is to provide the above-mentioned microorganism-carrying Fe0Bentonite-modified biochar and Fe-based as described above0Application of a composite permeable reactive wall system of bentonite modified biochar filler.
In order to solve the first technical problem, the invention discloses Fe loaded with microorganisms0-a process for the preparation of bentonite-modified biochar comprising the steps of:
s1: fully stirring and uniformly mixing bentonite and biochar, standing, and pyrolyzing in an inert atmosphere to obtain bentonite modified biochar;
s2: stirring and fully mixing the bentonite modified biochar obtained in the step S1 with zero-valent iron to obtain Fe0-bentonite modified biochar;
s3: fe obtained in step S20Mixing the bentonite modified charcoal and the bacterial liquid, and oscillating in a constant temperature shaking table to obtain the Fe loaded with the microorganisms0-bentonite modified biochar;
in step S3, the bacterial liquid is activated by clostridium, pseudomonas and alcaligenes denitrificans.
In the step S1, the particle size of the bentonite is 80-200 meshes, and the particle size of the biochar is 10-24 meshes; the mass ratio of the bentonite to the biochar is 1 (10-20); the mixing is carried out for 30-60 min at the speed of 500-600 r/min; the standing time is 40-56 hours, preferably 48 hours; the pyrolysis is carried out at 500-600 ℃ for 40-60 min.
In step S2, the grain size of the zero-valent iron is 100-200 meshes; the mass of the zero-valent iron is 10-30% of that of the biochar; the mixing is carried out by stirring at 400-800 r/min for 40-60 min.
In the step S3, the volume of the bacterial liquid is 3-10 mL/g of charcoal; the oscillating rotating speed is 200-250 r/min.
In order to solve the second technical problem, the invention discloses a Fe-based alloy0-bentonite modified biochar filler composite permeable reactive barrier system, which is sequentially provided with quartz sand water inlet layer and Fe0A bentonite modified charcoal layer, a resin layer and a quartz sand water outlet layer.
Wherein, the Fe0An injection well is arranged in the bentonite modified charcoal layer, and the rest part is filled with the Fe loaded with the microorganisms prepared by the method0-a mixture of bentonite modified biochar and quartz sand with a particle size of 2-4 mm, said Fe0The bentonite modified charcoal layer can adsorb, chemically reduce and biodegrade pollutants in groundwater.
The well wall of injection well is equipped with a plurality of delivery holes uniformly for the layering location injects nutrient solution, and the quantity of delivery hole and injection well is adjusted according to permeable reactive barrier actual conditions, and the delivery hole all is equipped with sand prevention otter board.
The nutrient solution comprises one or two of monopotassium phosphate, sodium sulfate, ammonium sulfate, magnesium sulfate, potassium chloride and zinc sulfate.
Wherein, the Fe0-bentonite modified biochar layer, said microorganism-laden Fe0The volume ratio of the bentonite modified biochar to the quartz sand is 7: 3-3: 7.
The quartz sand water inlet layer and the quartz sand water outlet layer are both quartz sand, and both the quartz sand water inlet layer and the quartz sand water outlet layer have the functions of filtering and draining underground water; wherein the particle size of the quartz sand is 2-4 mm; the length of the quartz sand water inlet layer and the length of the quartz sand water outlet layer are both 5-50 cm.
The resin layer is a mixture of macroporous adsorption resin and anion exchange resin, the volume ratio of the macroporous adsorption resin to the anion exchange resin is 1 (0.7-1.3), preferably 1:1, the resin layer can adsorb byproducts of pollutants which are difficult to degrade, and secondary pollution is avoided in the groundwater remediation process.
Wherein, the quartz sand enters the water inlet layer and Fe0The lengths of the bentonite modified biochar layer, the resin layer and the quartz sand effluent layer are determined according to the actual condition of the groundwater polluted by the specific chlorinated organic compounds and the nitrate, the remediation target and the like.
Wherein, the permeable reactive wall system further comprises a pump and a conveying pipeline for conveying the nutrient solution.
In order to solve the third technical problem, the invention discloses the microorganism-loaded Fe prepared by the method0Bentonite modified biochar and the use of the permeable reactive wall system for removing chlorinated organics and/or nitrates, preferably in groundwater.
Has the advantages that: compared with the prior art, the invention has the following advantages:
(1) the composite permeable reactive barrier is sequentially provided with a quartz sand water inlet layer and Fe0A bentonite modified charcoal layer, a resin layer and a quartz sand water outlet layer. Wherein, the water inlet layer and the water outlet layer of the quartz sand have the functions of filtering and draining the underground water; fe0The bentonite modified charcoal layer is loaded with microorganisms, and chlorinated organic matters and nitrates in the underground water are efficiently and durably removed through adsorption, chemical reduction and biodegradation; for the poisonous and harmful by-products difficult to degrade, the resin layer can completely absorb the harmful by-productsAnd the secondary pollution to the underground water is avoided.
(2) The composite permeable reactive barrier can realize no secondary pollution of degradation byproducts, high removal rate and long service life in the groundwater remediation process and can efficiently and durably remove chlorinated organic matters and nitrates in groundwater through an adsorption-chemical reduction-degradation-re-adsorption composite mechanism.
(3) Fe in the composite permeable reactive barrier of the invention0The bentonite modified charcoal layer can continuously and slowly release the carbon source to provide energy required by the growth and the propagation of microorganisms, the bentonite modified charcoal can effectively adjust the permeability of the permeable reactive barrier to prevent blockage, and the continuous and slow release of the carbon source can effectively ensure the service life of the permeable reactive barrier.
(4) The injection well can realize layered positioning injection of nutrient solution, and fully ensure that nutrient substances required by microorganisms are uniformly distributed in the permeable reactive barrier.
Drawings
The foregoing and/or other advantages of the invention will become further apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.
FIG. 1 is a Fe-based alloy0Schematic representation of a composite permeable reactive wall system of bentonite modified biocarbon packing.
FIG. 2 shows the concentration of the pollutant o-chloronitrobenzene and its degradation product (a) and the pollutant nitrate nitrogen and its degradation product (b) in effluent water as a function of time (1-450 days) (the initial concentration of o-chloronitrobenzene and nitrate nitrogen is 10 mg/L).
FIG. 3 shows the concentration of the pollutant o-chloronitrobenzene and its degradation product (a) and the pollutant nitrate nitrogen and its degradation product (b) in effluent over time (1-450 days) (the initial concentration of o-chloronitrobenzene and nitrate nitrogen is 15 mg/L).
FIG. 4 shows the concentration of the pollutant o-chloronitrobenzene and its degradation product (a) and the pollutant nitrate nitrogen and its degradation product (b) in effluent water as a function of time (1-450 days) (the initial concentration of o-chloronitrobenzene and nitrate nitrogen is 20 mg/L).
Detailed Description
The experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials are commercially available, unless otherwise specified.
The following examples provide a Fe-based alloy0A composite permeable reactive barrier system of bentonite modified biochar filler, and a preparation method and application thereof, as shown in figure 1, wherein the composite permeable reactive barrier system is formed by feeding quartz sand into a water layer and Fe0A bentonite modified charcoal layer, a resin layer and a quartz sand water outlet layer. Wherein, the quartz sand water inlet layer has the functions of filtering and draining the underground water, and ensures that the underground water continuously flows into Fe firstly in the running process of the permeable reactive barrier system0The bentonite modified biochar layer sequentially flows through the resin layer and the quartz sand water outlet layer, and flows out of the permeable reactive barrier after adsorption-chemical reduction-biodegradation-reabsorption cooperative treatment. During operation of the composite permeable reactive wall system, nutrient solution can be pumped into the injection well through the delivery pipeline to Fe0The nutrient solution is injected into the bentonite modified charcoal layer in a layered and positioned way and is Fe0The microorganisms loaded in the bentonite modified biochar provide nutrients required for growth and reproduction.
Example 1
1、Fe0-bentonite modified charcoal layer
(1) Preparation of Fe0-bentonite modified biochar:
(a) fully stirring and uniformly mixing bentonite and coconut shell biochar according to a mass ratio of 1:20, wherein the stirring speed is 500r/min, the stirring time is 30min, and then standing for 48 h;
(b) mixing the mixed material in the step (a) in N2Pyrolyzing in the atmosphere at 500 ℃ for 40min to obtain bentonite modified biochar;
(c) fully stirring and uniformly mixing the bentonite modified biochar in the step (b) with zero-valent iron, wherein the mass of the zero-valent iron is 10% of that of the biochar, the stirring speed is 400r/min, and the stirring time is 40min, so as to obtain Fe0-bentonite modified biochar.
Wherein the particle size of the biochar is 10 meshes, the particle size of the bentonite is 80 meshes, and the particle size of the zero-valent iron is 100 meshes.
(2) Preparation of microorganism-supporting Fe0-bentonite modified biochar
The Fe prepared in the step 1 is mixed0Uniformly mixing bentonite modified biochar with bacterial liquid, oscillating in a constant temperature shaking table at the rotating speed of 200rpm/min, the temperature of 37 ℃ and the time of 24 hours to obtain Fe loaded with microorganisms0-bentonite modified biochar.
The using amount of the bacterial liquid is 3mL/g coconut shell biochar, and specifically the bacterial liquid after the activation of clostridium (GY-266493), Pseudomonas (GY-238245) and denitrifying alkaline-producing bacteria (GY-303239); the volume ratio of the three bacterium liquids of the clostridium, the pseudomonas and the denitrifying alcaligenes is 1:1: 1.
(3) Preparation of Fe0-bentonite modified charcoal layer
Said Fe0The bentonite modified biochar layer is the microorganism-loaded Fe prepared by step 20The bentonite modified biochar and the quartz sand with the particle size of 2mm are mixed uniformly according to the volume ratio of 4:6 and filled.
(4) Said Fe 04 injection wells are vertically and uniformly arranged in the bentonite modified charcoal layer, 6 conveying holes are vertically and uniformly formed in the well wall of each injection well, and sand-proof mesh plates are arranged in the conveying holes and used for injecting nutrient solution in a layered and positioned mode.
The nutrient solution comprises the components of monopotassium phosphate, sodium sulfate and ultrapure water, and the mass ratio of the components is 1:1: 18.
2. The resin layer is formed by uniformly mixing and filling macroporous absorption resin (model: XDA-1, H-103) and styrene series strong base anion exchange resin (model: 717), wherein the volume ratio of the XDA-1 macroporous absorption resin to the H-103 macroporous absorption resin is 1:1, and the volume ratio of the macroporous absorption resin to the anion exchange resin is 1: 1.
3. The quartz sand water inlet layer and the quartz sand water outlet layer are both formed by filling quartz sand, and the particle size of the quartz sand is 2 mm.
In this example, the length of the water inlet layer of the quartz sand is 5cm, and Fe0The length of the bentonite modified biochar layer is 10cm, the length of the resin layer is 10cm, the length of the quartz sand effluent layer is 5cm, the width of the composite permeable reactive barrier is 10cm, and the height of the composite permeable reactive barrier is 10 cm.
Preparation of o-chloronitrobenzene and nitrate Nitrogen (NO) with ultrapure water3-N), wherein the concentration of o-chloronitrobenzene is 10mg/L and the concentration of nitrate nitrogen is 10 mg/L. And (3) introducing the composite solution into the composite permeable reactive wall system by using a peristaltic pump (the flow rate is 150 mu L/min), wherein the running time is 450 days. When the experiment operation is started, 100mL of nutrient solution is conveyed into each injection well through a conveying pipeline, the nutrient solution permeates into the permeable reactive barrier through the conveying holes on the wall of the injection well, and the nutrient solution is replenished again according to the steps after two months. The concentration changes of o-chloronitrobenzene, nitrate nitrogen and degradation products thereof are monitored at the water outlet, and the monitoring result is shown in figure 2. In the operation process of 450 days, the concentrations of o-chloronitrobenzene and degradation products thereof, i.e., o-chloroaniline and aniline, are not detected. In addition, in the initial stage, the concentration of nitrate nitrogen and the concentration of degradation products thereof in the effluent are 0.3-0.5 mg/L, and after 50 days, the concentrations of nitrate nitrogen and the concentration of degradation products thereof in the effluent are not detected. The result shows that the composite permeable reactive barrier provided by the embodiment can realize efficient and durable removal of o-chloronitrobenzene and nitrate nitrogen in underground water, has no secondary pollution of degradation byproducts, and has long service life.
Example 2: based on Fe0The composite permeable reactive barrier system of bentonite modified biochar filler and the preparation method thereof are basically the same as example 1, except that:
1、Fe0-bentonite modified charcoal layer
(1) Preparation of Fe0-bentonite modified biochar:
(a) fully stirring and uniformly mixing bentonite and coconut shell biochar according to a mass ratio of 1:15, wherein the stirring speed is 550r/min, the stirring time is 40min, and then standing for 48 h;
(b) subjecting the mixture of step (a)Mixing materials in N2Pyrolyzing in the atmosphere at 550 ℃ for 50min to obtain bentonite modified biochar;
(c) fully stirring and uniformly mixing the bentonite modified biochar in the step (b) with zero-valent iron, wherein the mass of the zero-valent iron is 20% of that of the biochar, the stirring speed is 600r/min, and the stirring time is 50min, so as to obtain Fe0-bentonite modified biochar.
Wherein the particle size of the biochar is 15 meshes, and the particle size of the bentonite and the zero-valent iron is 150 meshes.
(2) Preparation of microorganism-supporting Fe0-bentonite modified biochar
The shaking table speed is 220rpm/min, the bacterial liquid dosage is 5mL/g coconut shell biochar, and the rest steps and parameters are the same as those in example 1.
(3) Preparation of Fe0-bentonite modified charcoal layer
Said Fe0The bentonite modified biochar layer is the microorganism-loaded Fe prepared by step 20The bentonite modified biochar and the quartz sand with the grain diameter of 3mm are uniformly mixed and filled according to the volume ratio of 1: 1.
(4) Said Fe 04 injection wells are vertically and uniformly arranged in the bentonite modified charcoal layer, 8 conveying holes are vertically and uniformly formed in the well wall of each injection well, and sand-proof mesh plates are arranged in the conveying holes and used for injecting nutrient solution in a layered and positioned mode.
The nutrient solution comprises the components of monopotassium phosphate, magnesium sulfate and ultrapure water, and the mass ratio of the components is 1:1: 18.
2. The resin layer was the same as in example 1.
3. The quartz sand water inlet layer and the quartz sand water outlet layer are both formed by filling quartz sand, and the particle size of the quartz sand is 3 mm.
In this example, the length of the water inlet layer of the quartz sand is 10cm, and Fe0The length of the bentonite modified biochar layer is 20cm, the length of the resin layer is 20cm, the length of the quartz sand effluent layer is 10cm, the width of the composite permeable reactive barrier is 15cm, and the height of the composite permeable reactive barrier is 15 cm.
With ultra-pure waterWater configuration with ortho-chloronitrobenzene and nitrate Nitrogen (NO)3-N), wherein the concentration of o-chloronitrobenzene is 15mg/L and the concentration of nitrate nitrogen is 15 mg/L. And (3) introducing the composite solution into the composite permeable reactive wall system by using a peristaltic pump (the flow rate is 160 mu L/min), wherein the running time is 450 days. When the experiment operation is started, 200mL of nutrient solution is conveyed into each injection well through a conveying pipeline, the nutrient solution permeates into the permeable reactive barrier through the conveying holes on the wall of the injection well, and the nutrient solution is replenished again according to the steps after two months. The concentration changes of o-chloronitrobenzene, nitrate nitrogen and degradation products thereof are monitored at the water outlet, and the monitoring result is shown in figure 3. In the operation process of 450 days, the concentrations of o-chloronitrobenzene and degradation products thereof, i.e., o-chloroaniline and aniline, are not detected. In addition, in the initial stage, the concentration of nitrate nitrogen and the concentration of degradation products thereof in the effluent are 0.4-0.7 mg/L, and after 50 days, the concentrations of nitrate nitrogen and the concentration of degradation products thereof in the effluent are not detected. The result shows that the composite permeable reactive barrier provided by the embodiment can realize efficient and durable removal of o-chloronitrobenzene and nitrate nitrogen in underground water, has no secondary pollution of degradation byproducts, and has long service life.
Example 3: based on Fe0The composite permeable reactive barrier system of bentonite modified biochar filler and the preparation method thereof are basically the same as example 1, except that:
1、Fe0-bentonite modified charcoal layer
(1) Preparation of Fe0-bentonite modified biochar:
(a) fully stirring and uniformly mixing bentonite and coconut shell biochar according to a mass ratio of 1:10, wherein the stirring speed is 600r/min, the stirring time is 60min, and then standing for 48 h;
(b) mixing the mixed material in the step (a) in N2Pyrolyzing in the atmosphere at 600 ℃ for 60min to obtain bentonite modified biochar;
(c) fully stirring and uniformly mixing the bentonite modified biochar in the step (b) with zero-valent iron, wherein the mass of the zero-valent iron is 30% of that of the biochar, and stirringThe speed is 800r/min, the stirring time is 60min, and Fe is obtained0-bentonite modified biochar.
Wherein the particle size of the biochar is 24 meshes, and the particle size of the bentonite and the zero-valent iron is 200 meshes.
(2) Preparation of microorganism-supporting Fe0-bentonite modified biochar
The shaking table speed is 250rpm/min, the bacterial liquid dosage is 8mL/g coconut shell biochar, and the rest steps and parameters are the same as those in example 1.
(3) Preparation of Fe0-bentonite modified charcoal layer
Said Fe0The bentonite modified biochar layer is the microorganism-loaded Fe prepared by step 20The bentonite modified biochar and the quartz sand with the particle size of 4mm are mixed uniformly according to the volume ratio of 6:4 and filled.
(4) Said Fe 04 injection wells are vertically and uniformly arranged in the bentonite modified charcoal layer, 10 conveying holes are vertically and uniformly formed in the well wall of each injection well, and sand-proof mesh plates are arranged in the conveying holes and used for injecting nutrient solution in a layered and positioned mode.
The nutrient solution comprises the components of monopotassium phosphate, zinc sulfate and ultrapure water, and the mass ratio of the components is 1:1: 18.
2. The resin layer was the same as in example 1.
3. The quartz sand water inlet layer and the quartz sand water outlet layer are both formed by filling quartz sand, and the particle size of the quartz sand is 4 mm.
In this example, the length of the water inlet layer of the quartz sand is 15cm, and Fe0The length of the bentonite modified biochar layer is 30cm, the length of the resin layer is 30cm, the length of the quartz sand effluent layer is 15cm, the width of the composite permeable reactive barrier is 20cm, and the height of the composite permeable reactive barrier is 20 cm.
Preparation of o-chloronitrobenzene and nitrate Nitrogen (NO) with ultrapure water3-N), wherein the concentration of o-chloronitrobenzene is 20mg/L and the concentration of nitrate nitrogen is 20 mg/L. And (3) introducing the composite solution into the composite permeable reactive wall system by using a peristaltic pump (the flow rate is 170 mu L/min), wherein the running time is 450 days. Fruit of Chinese wolfberryAt the beginning of the test operation, 300mL of nutrient solution is conveyed into each injection well through a conveying pipeline, the nutrient solution permeates into the permeable reactive walls through conveying holes on the walls of the injection wells, and the nutrient solution is replenished according to the steps after two months. The concentration changes of o-chloronitrobenzene, nitrate nitrogen and degradation products thereof are monitored at the water outlet, and the monitoring result is shown in figure 4. In the operation process of 450 days, the concentrations of o-chloronitrobenzene and degradation products thereof, i.e., o-chloroaniline and aniline, are not detected. In addition, in the initial stage, the concentration of nitrate nitrogen and the concentration of degradation products thereof in the effluent are 0.5-0.8 mg/L, and after 50 days, the concentrations of nitrate nitrogen and the concentration of degradation products thereof in the effluent are not detected. The result shows that the composite permeable reactive barrier provided by the embodiment can realize efficient and durable removal of o-chloronitrobenzene and nitrate nitrogen in underground water, has no secondary pollution of degradation byproducts, and has long service life.
The invention provides a Fe-based alloy0The idea and method for the composite permeable reactive wall system of bentonite modified biocarbon filler and the application thereof, and the method and way for implementing the technical solution are many, and the above description is only a preferred embodiment of the present invention, it should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should be considered as the protection scope of the present invention. All the components not specified in the present embodiment can be realized by the prior art.

Claims (10)

1. Microorganism-loaded Fe0The preparation method of the bentonite modified biochar is characterized by comprising the following steps:
s1: uniformly mixing bentonite and biochar, standing and pyrolyzing to obtain bentonite modified biochar;
s2: mixing the bentonite modified biochar obtained in the step S1 with zero-valent iron to obtain Fe0-bentonite modified biochar;
s3: fe obtained in step S20The bentonite modified charcoal is mixed with the bacterial liquid evenly and oscillated to obtain the Fe loaded with the microorganism0-modified bentonite clayCharcoal;
in step S3, the bacterial liquid is activated by clostridium, pseudomonas and alcaligenes denitrificans.
2. The method according to claim 1, wherein in step S1, the particle size of the bentonite is 80 to 200 mesh, and the particle size of the biochar is 10 to 24 mesh; the mass ratio of the bentonite to the biochar is 1 (10-20); the mixing is carried out for 30-60 min at the speed of 500-600 r/min; the standing time is 40-56 h; the pyrolysis is carried out at 500-600 ℃ for 40-60 min.
3. The method according to claim 1, wherein in step S2, the particle size of the zero-valent iron is 100 to 200 mesh; the mass of the zero-valent iron is 10-30% of that of the biochar; the mixing is carried out by stirring at 400-800 r/min for 40-60 min; in the step S3, the volume of the bacterial liquid is 3-10 mL/g of charcoal; the oscillating rotating speed is 200-250 r/min.
4. Based on Fe0The composite permeable reactive barrier system of bentonite modified biochar filler is characterized in that a quartz sand water inlet layer and Fe are sequentially arranged on the composite permeable reactive barrier system0-a bentonite modified biochar layer, a resin layer and a quartz sand effluent layer;
wherein, the Fe0-an injection well is arranged in the bentonite modified charcoal layer, and the rest part is filled with the Fe loaded with the microorganisms prepared by the method of any one of claims 1 to 30-bentonite modified biochar and quartz sand.
5. The composite permeable reactive wall system of claim 4, wherein the wall of the injection well is provided with transportation holes for layered positioning of the injected nutrient solution.
6. The composite permeable reactive barrier system of claim 5, wherein the nutrient solution comprises one or a combination of two of potassium dihydrogen phosphate, sodium sulfate, ammonium sulfate, magnesium sulfate, potassium chloride and zinc sulfate.
7. The composite permeable reactive wall system of claim 4, wherein the Fe0-bentonite modified biochar layer, said microorganism-laden Fe0The volume ratio of the bentonite modified biochar to the quartz sand is 7: 3-3: 7.
8. The composite permeable reactive wall system of claim 4, wherein the resin layer is a mixture of macroporous adsorbent resin and anion exchange resin.
9. The composite permeable reactive barrier system according to claim 4, wherein the water inlet layer and the water outlet layer are both quartz sand, and the particle size of the quartz sand is 2-4 mm; the length of the quartz sand water inlet layer and the length of the quartz sand water outlet layer are both 5-50 cm.
10. Microorganism-loaded Fe prepared by the method of any one of claims 1 to 30-bentonite modified biochar, or the use of a permeable reactive wall system according to any of claims 4 to 9 for removing chlorinated organics and/or nitrates.
CN202210048918.8A 2022-01-17 2022-01-17 Based on Fe0Composite permeable reactive barrier system of bentonite modified biochar filler and application thereof Pending CN114249507A (en)

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