Method for accurately blocking and controlling uranium-containing wastewater by using stepped self-driven ecological filter tank in high and cold fragile ecological region

Abstract

The invention discloses a method for accurately blocking and controlling uranium-containing wastewater by using a cascade self-driven ecological filter in a high and cold fragile ecological region, which comprises the following steps: collecting uranium-containing multi-metal wastewater, and measuring the water body of the uranium-containing multi-metal wastewater; preparing simulated multi-metal wastewater according to the content of metal elements in the uranium-containing multi-metal wastewater; performing static adsorption test on the simulated multi-metal wastewater by using natural ecological minerals, multifunctional fiber materials and bryophytes respectively; and building the cascade self-driven ecological filter containing the bryophytes according to a test result in the step 3. The purpose of purifying the uranium wastewater is achieved by building the ecological filter and filling the ecological filter with the novel uranium removal material and the bryophyte, the ecological filter adsorbs uranium and various metals in the uranium-containing wastewater in a cascade self-driving mode, and the uranium-containing wastewater is deeply purified through multiple layers and multiple materials. The method not only can achieve the purpose of deep purification of uranium-containing wastewater, but also has the characteristic of environmental friendliness, and has extremely high practical value and practical significance.

Description

Technical Field

[0001] The present invention belongs to the field of various heavy metal treatments, and in particular relates to a method for accurately blocking and controlling uranium-containing wastewater using cascade self-driven ecological filters in high-altitude and fragile ecological zones. Background Art

[0002] In the international context of "dual carbon" initiatives, the secure supply and maintenance of uranium resources is a major national imperative. The development of nuclear energy is inseparable from uranium mining. Not only does uranium mining, processing, and hydrometallurgy cause environmental pollution, but the uranium tailings produced after uranium mining also have a lasting negative impact on the ecological environment. The debris, residues, dust, and wastewater left over from uranium mining and smelting continue to pollute the local environment, threatening soil nutrients, air quality, water safety, and biodiversity. The self-repair capacity of ecosystems is limited, and the ecological environment in uranium mining areas is unlikely to recover without human intervention.

[0003] my country's tailings are characterized by large numbers, large storage capacities, extensive land areas, and severe complex pollution. Mine wastewater contains a large number of harmful metal and non-metal ions, including rapidly toxic elements such as mercury, cadmium, arsenic, and lead, as well as copper, manganese, and zinc. If tailings management is inadequate, this wastewater will seep into surface and groundwater, and subsequently invade the soil. This will not only severely impact the surrounding ecology but also spread through geochemical cycles to densely populated areas, threatening human survival.

[0004] In order to achieve efficient restoration of uranium mines, separating and recovering uranium from uranium wastewater can not only improve the efficiency of nuclear energy utilization, but also reduce the potential threat of uranium to the ecological environment and human health. As a heavy metal, uranium has high radiotoxicity and chemical toxicity. It is often found in water in the form of hexavalent uranium (UO2 2+) exists. When the pH rises, uranyl ions begin to hydrolyze strongly when the pH is greater than 3, and can be completely precipitated at a pH of 5-6. Therefore, under low pH conditions, uranium is easier to disperse and migrate. Therefore, the treatment difficulty and cost of polymetallic uranium-containing wastewater in mining areas are very challenging, and multiple technologies need to be used in combination to achieve the ideal treatment effect. At present, the treatment technologies for uranium-containing wastewater include chemical precipitation, ion exchange, adsorption, membrane separation, microbial method, etc. Although the existing technologies are mature, they have their own limitations. For example, the precipitated sludge produced in the chemical precipitation method needs further treatment (such as solidification), which may cause secondary pollution, and the removal rate of low-concentration uranium is limited; although the ion exchange method has a high removal coefficient and is suitable for low-concentration wastewater (uranium concentration <1000 mg / L), the resin cost is high, the regeneration process is complicated, and it is easily interfered with by other ions; if microbial remediation is used, although it is environmentally friendly, it requires long-term cultivation. Therefore, practical methods are needed for practical application. The limitations of existing technologies urgently require a new technology with greater potential in efficiency and environmental protection, the development of low-cost, highly selective adsorption materials, the optimization of biochemical remediation processes, and the promotion of the industrialization of uranium-containing wastewater treatment technology. Summary of the Invention

[0005] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0006] To achieve these objectives and other advantages of the present invention, a method for accurately blocking and controlling uranium-containing wastewater in a cascade self-driven ecological filter in a high-altitude and fragile ecological zone is provided, comprising the following steps:

[0007] Step 1: Collect uranium-containing and polymetallic wastewater and measure its water quality;

[0008] Step 2: preparing simulated polymetallic wastewater according to the content of metal elements in the uranium-containing polymetallic wastewater;

[0009] Step 3: Conduct static adsorption tests on simulated polymetallic wastewater using natural ecological minerals, multifunctional fiber materials, and moss plants;

[0010] Step 4: Build a cascade self-driven ecological filter containing moss plants based on the test results of step 3.

[0011] Preferably, in step 1, uranium-containing polymetallic wastewater is collected from underground seepage water of a uranium mine, and when measuring the water body, its pH, dissolved oxygen, TOC, TN, TP and the content of each metal element are measured, including the metal oxidation state, reduction state, residual state and acid solubility state.

[0012] Preferably, in the step 2, the specific method for preparing the simulated polymetallic wastewater is: adding UO2(NO3)2·6H2O, Pb(NO)3, Fe(NO3)2, Mn(NO3)2, and Zn(NO3)2 in a dosage ratio of 50-100 mg:0.1-0.5 mg:5-10 mg:1-10 mg:15-20 mg to 1 L of ultrapure water to prepare simulated uranium mining area polymetallic wastewater.

[0013] Preferably, in step three, the natural ecological mineral is biochar, and the method for conducting a static adsorption test using the natural ecological mineral is: weigh 1 to 2 g of the natural ecological mineral and place it in a 250 mL conical flask, add 100 to 200 mL of simulated multi-metal wastewater, seal it with a sealing film and a rubber band, and culture it in a constant temperature shaking incubator at 25°C for 24 hours. After filtering through a 0.45 micron filter membrane, the content of heavy metal ions in the filtrate is determined using an ICP-OES spectrometer.

[0014] Preferably, in step three, the multifunctional fiber material is polyamine / amidoxime polyacrylonitrile fiber, and the method for conducting a static adsorption test using the multifunctional fiber material is as follows: weigh 0.05-0.1 g of the multifunctional fiber material and place it in a 250 mL conical flask, add 100-200 mL of simulated multi-metal wastewater, seal it with a sealing film and a rubber band, and shake and culture it in a constant temperature shaking incubator at 25°C for 24 hours. After filtering through a 0.45 micron filter membrane, the content of heavy metal ions in the filtrate is determined by an ICP-OES spectrometer.

[0015] Preferably, in the step three, the specific method of conducting a static adsorption test on simulated multi-metal wastewater using moss plants is as follows: bring the moss plants collected in the wild back to the laboratory, pick out the weeds and soil clods therefrom, rinse the dust on the surface of the plants with tap water, and rinse them several times with deionized water to remove the metal ions on the surface; divide the washed moss plants into small pieces of 8×8 cm, place them in a culture pot filled with pine needle matrix for cultivation, add 50 mL of simulated multi-metal wastewater regularly every day, and after culturing for 30 to 60 days, take a certain amount of soil for digestion and determine the content of metal ions therein; and calculate the heavy metal ion removal rate.

[0016] Preferably, before conducting the static adsorption test, the biochar is modified by soaking the biochar in a sodium citrate solution, taking it out after fully soaking it, heat-treating it in an oxygen-free environment, cooling it and then soaking it in a sodium hydroxide solution, and finally washing and drying it to obtain the modified biochar.

[0017] Preferably, the concentration of the sodium citrate solution is 0.1-0.5 mol / L, the mass volume ratio of biochar and sodium citrate solution is kg / L=1-2:10-15, the heat treatment temperature is 300-400°C, the heat treatment time is 1-2h, the concentration of the sodium hydroxide solution is 2-4 mol / L, and the mass volume ratio of biochar and sodium hydroxide solution is kg / L=1-2:5-10.

[0018] The present invention also provides a stepped self-driven ecological filter containing moss plants, comprising a water distribution unit, a flow control unit, a pretreatment unit, an ecological mineral filler unit, a multifunctional fiber material filler unit, a plant growth unit, and a water collection unit, which are sequentially lowered from left to right; the water distribution unit is connected to the pretreatment unit through the flow control unit, and the flow control unit is provided with a valve.

[0019] Preferably, the ecological mineral filler unit is, from bottom to top, quartz sand with a layer height of 150 to 250 mm, biochar with a layer height of 550 to 650 mm, and gravel with a layer height of 150 to 250 mm; the multifunctional fiber material filler unit is, from bottom to top, polyamine / amidoxime polyacrylonitrile fiber with a layer height of 550 to 650 mm, a porous plate, and gravel with a layer height of 150 to 250 mm; the plant growth unit is, from top to bottom, a moss plant layer, a clay filter layer with a layer height of 400 to 450 mm, a sand and gravel filter layer with a layer height of 50 to 150 mm, and gravel with a layer height of 50 to 150 mm.

[0020] The present invention includes at least the following beneficial effects: The content of the present invention is to achieve the purpose of purifying uranium wastewater by constructing an ecological filter and filling it with a new uranium removal material. The ecological filter adsorbs multiple metals in the uranium-containing wastewater in a stepped self-driven manner. The uranium-containing wastewater is deeply purified by multiple levels and multiple materials. It can not only achieve the purpose of deep purification of uranium-containing wastewater, but also has environmentally friendly characteristics, and has extremely high practical value and practical significance. The quartz sand in the ecological mineral filler unit has the characteristics of high hardness, wear resistance, high temperature resistance, and good chemical stability, which can effectively improve the filtration efficiency. It is placed at the bottom of the filter as an excellent support material. The biochar therein can efficiently adsorb and solidify ammonia nitrogen and heavy metals in the water, and can also efficiently remove organic pollutants in the water. The ion exchange adsorption fiber material (polyamine / amidoxime polyacrylonitrile fiber) in the multifunctional fiber material filler unit has exchangeable ionic groups on its surface. These ionic groups can exchange with like-charged ions in the surrounding solution, thereby achieving the adsorption and removal of metal ions. The moss plants in the plant growth unit can effectively absorb heavy metal ions through extracellular enrichment and intracellular absorption. As pioneer plants in the ecological restoration of uranium mines, their wide distribution in the ecosystem makes them occupy an important position. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the cascade ecological filter constructed according to Example 1 of the present invention. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below with reference to the embodiments so that those skilled in the art can implement the invention with reference to the description.

[0023] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0024] Example 1

[0025] A method for accurately blocking and controlling uranium-containing wastewater in a cascade self-driven ecological filter in a high-altitude and fragile ecological zone comprises the following steps:

[0026] Step 1: Collect underground seepage water from a uranium mine as uranium-containing polymetallic wastewater. When measuring the water body, its pH, dissolved oxygen, TOC, TN, TP, and the content of each metal element are measured, including the metal oxidation state, reduced state, residual state, and acid solubility state. The results of basic physical and chemical property measurements, as shown in Tables 1 and 2, show that the uranium-containing wastewater is generally neutral to alkaline, and the TN and TP contents in the water body are low. It is poor in nutrients, which restricts the growth of aquatic organisms and affects the diversity of the ecosystem.

[0027] Table 1

[0028]

[0029] Table 2

[0030]

[0031] Step 2: Because the composition of collected groundwater is complex, real uranium-containing wastewater contains multiple ions, organic matter, and suspended solids, which may obscure the uranium adsorption mechanism. Simulated wastewater can eliminate interfering factors by using a single uranium ion or a simple solution formula to clarify the adsorbent's selectivity for uranium and its adsorption mechanism. Fitting adsorption isotherms and kinetic models through static experimental data provides theoretical support for dynamic experiments or engineering scale-up. In addition, the cost of real wastewater treatment is high, while simulation experiments can reduce consumption and lower the cost of early research and development, laying a reliable foundation for the design and optimization of real wastewater treatment processes. 100 mg UO2(NO3)2·6H2O, 0.1 mg Pb(NO)3, 10 mg Fe(NO3)2, 10 mg Mn(NO3)2, and 20 mg Zn(NO3)2 are added to 1 L of ultrapure water to prepare a uranium stock solution with a uranium concentration of 0.1 g / L, which is a simulation of uranium-containing polymetallic wastewater in uranium mining areas. The concentrations of Pb(NO)3, Fe(NO3)2, Mn(NO3)2, and Zn(NO3)2 are 0.1 mg / L, 10 mg / L, 10 mg / L, and 20 mg / L, respectively.

[0032] Step 3: Static adsorption test using natural ecological minerals: 2g of biochar was weighed and placed in a 250mL conical flask. 100mL of simulated polymetallic wastewater was added, and the flask was sealed with sealing film and rubber band. The flask was incubated in a constant temperature shaking incubator at 25°C for 24 hours. The flask was then centrifuged at 10,000 rpm for 10 minutes and filtered through a 0.22-micron filter membrane. The heavy metal ion content in the filtrate was determined using an ICP-OES spectrometer. The biochar had a uranium removal rate of 99.40% in the simulated uranium-containing polymetallic wastewater.

[0033] Static adsorption tests were conducted using multifunctional fiber materials: 0.1g of polyamine / amidoxime polyacrylonitrile fiber (PAN-AO-A) was weighed and placed in a 250mL conical flask. 100mL of simulated multimetallic wastewater was added, and the flask was sealed with sealing film and a rubber band. The flask was incubated in a constant temperature shaking incubator at 25°C for 24 hours. After filtering through a 0.22-micron filter membrane, the heavy metal ion content in the filtrate was determined using an ICP-OES spectrometer. The results showed that PAN-AO-A had a uranium removal rate of 99.70% in the simulated uranium-containing multimetallic wastewater. Furthermore, PAN-AO-A achieved an ideal high removal rate even in the presence of background metal ions.

[0034] Static adsorption test of simulated multi-metal wastewater was carried out using moss plants: moss plants collected from the wild were brought back to the laboratory, weeds and soil clods were picked out, dust on the surface of the plants was washed off with tap water, and metal ions were removed from the surface by rinsing with deionized water several times. The cleaned moss plants were divided into small pieces of 8×8 cm and placed in a culture pot filled with pine needle matrix for culture. 50 mL of simulated uranium-containing multi-metal wastewater was added regularly every day. After culturing for 30 days, 0.2 g of fresh moss samples (not stained with soil and dried with absorbent paper) were taken to determine the uranium content by digestion method and azoarsenic III spectrophotometry. The uranium removal amount can reach 115 mg / kg.

[0035] Step 4: Build the following according to the test results of step 3 Figure 1 The cascade self-driven ecological filter shown.

[0036] A cascade self-driven ecological filter containing moss plants includes a water distribution unit 1, a flow control unit 2, a pretreatment unit 3, an ecological mineral filler unit 4, a multifunctional fiber material filler unit 5, a plant growth unit 6, and a water collection unit 7, which are arranged in descending order from left to right; the water distribution unit 1 is connected to the pretreatment unit 3 through the flow control unit 2.

[0037] Working principle: The ecological filter system simulates the hydrodynamic environment of the mining area and adopts gravity flow control technology to construct a modular treatment system. The height difference between the water distribution unit 1, pretreatment unit 3, ecological mineral filler unit 4, functional fiber material filler unit 5, plant growth unit 6, and water collection tank 7 is reduced in sequence, so that the flow of uranium-containing wastewater can rely on its own gravity as the power to achieve vertical upward and vertical downward operation. The water distribution unit 1 transports the uranium-containing wastewater to the pretreatment unit 3 through the flow control unit 2. The uranium-containing wastewater is pre-aerated in the pretreatment unit to effectively promote the oxidative decomposition of harmful substances. At the same time, natural sedimentation and coagulation sedimentation methods are used to add coagulant ferrous sulfate to the wastewater to accelerate the precipitation of suspended matter and remove most of the suspended matter in the wastewater. The pretreated wastewater enters the biomineral filler unit 4 by gravity flow. When the wastewater reaches the designed liquid level in the biomineral filler unit 4, based on the hydraulic gradient designed by the system, the wastewater overflows into the multifunctional fiber filler unit 5. After the wastewater is adsorbed by the multifunctional fiber material filler unit 5, it flows into the plant growth unit 6 by gravity to complete deep purification. The purified water body is introduced into the water collection unit 7 through standardized overflow; the flow control unit 2 is provided with a valve 21, which can be used to control the flow rate.

[0038] In the above technical scheme, quartz sand 42 with a layer height of 200 mm, biochar 43 with a layer height of 600 mm, and gravel 41 with a layer height of 200 mm are added to the ecological mineral filler unit 4 from bottom to top; polyamine / amidoxime polyacrylonitrile fiber (PAN-AO-A) 53 with a layer height of 600 mm, a porous plate 52, and gravel 51 with a layer height of 200 mm are added to the multifunctional fiber material filler unit 5 from bottom to top; and a moss plant layer 61, a clay filter layer 62 with a layer height of 400 mm, a sand and gravel filter layer 63 with a layer height of 100 mm, and gravel 64 with a layer height of 100 mm are added to the plant growth unit from top to bottom.

[0039] Working principle: The biochar 43 in the biomineral filler unit 4 can efficiently adsorb and solidify ammonia nitrogen and heavy metals in water, and can also efficiently remove organic pollutants in wastewater; the polyamine / amidoxime polyacrylonitrile fiber (PAN-AO-A) 53 in the multifunctional fiber material filler unit 5 has the remarkable feature of having exchangeable ionic groups on its surface, which can exchange with ions of the same charge in the surrounding solution, thereby achieving the adsorption and removal of metal ions; the moss plant layer 61 in the plant growth unit 6 realizes the triple removal mechanism of extracellular adsorption-intracellular transportation-vacuolar compartmentation of heavy metals through rhizosphere microenvironment regulation and biological enrichment effect.

[0040] The present invention constructs a hierarchical coupling treatment system: the ecological mineral filler unit 4 uses biochar (specific surface area> 1200m 2 / g) achieves chemical adsorption and valence state conversion of uranium. The multifunctional fiber material filler unit 5 chelates U(IV) ions through physical and chemical adsorption mediated by polyamine / amidoxime polyacrylonitrile fiber (PANAO-A) to form a stable structure. The plant growth unit 6 is equipped with moss for deep enrichment. Experimental results show that the cascade self-driven ecological filter achieved a removal rate of 98.50% when treating actual uranium-containing wastewater with an initial uranium concentration of 52 mg / L. The overall operating cost was reduced by 45% compared to traditional processes, successfully overcoming the three technical challenges of high environmental risk, low treatment efficiency, and high operating costs in uranium-containing wastewater treatment.

[0041] Example 2

[0042] Based on this embodiment and embodiment 1, the biochar added in step three and the ecological mineral filler unit 4 is modified by soaking 1 kg of biochar in 10 L of a sodium citrate solution with a concentration of 0.3 mol / L, taking out the biochar after it is fully soaked, and heat-treating it at 350°C in an oxygen-free environment for 2 h. After cooling, washing and drying, the biochar treated with sodium citrate is obtained.

[0043] The remaining steps are consistent with those in Example 1.

[0044] When static adsorption experiments were conducted using biochar treated with sodium citrate, the uranium removal rate in simulated uranium-containing polymetallic wastewater reached 99.66%; when using biochar treated with sodium citrate to build an ecological mineral filler unit, the uranium removal rate of the cascade self-driven ecological filter for actual uranium-containing wastewater with an initial uranium concentration of 52 mg / L was 99.05%, which was because sodium citrate improved the adsorption capacity of biochar.

[0045] Example 3

[0046] Based on this embodiment and embodiment 1, the biochar added in step three and the ecological mineral filler unit 4 is modified by soaking 1 kg of biochar in 10 L of 0.3 mol / L sodium citrate solution. After the biochar is fully soaked, it is heat-treated at 350°C in an oxygen-free environment for 2 h. After cooling, it is soaked in 5 L of 3 mol / L sodium hydroxide solution. Finally, it is washed and dried to obtain modified biochar.

[0047] The remaining steps are consistent with those in Example 1.

[0048] When modified biochar was used for static adsorption experiments, the uranium removal rate in simulated uranium-containing polymetallic wastewater reached 99.93%; when modified biochar was used to build an ecological mineral filler unit, the uranium removal rate of the cascade self-driven ecological filter for actual uranium-containing wastewater with an initial uranium concentration of 52 mg / L was 99.74%. This is because sodium hydroxide reacts with the residual lignin or hemicellulose in the biochar to undergo alkaline hydrolysis, thereby removing the amorphous carbon matrix, releasing or expanding the original pores, and improving its adsorption capacity.

[0049] Comparative Example 1

[0050] The difference between this comparative example and Example 1 is that the moss plant layer in the plant growth unit 6 is replaced by a fern plant layer, and the remaining steps are consistent with Example 1.

[0051] When fern plants were used to construct plant growth unit 6, the cascade self-driven ecological filter achieved a uranium removal rate of only 85.27% for actual uranium-containing wastewater with an initial uranium concentration of 52 mg / L. This is due to the complex soil-plant rhizosphere environmental system, where factors such as pH, organic matter, and cation exchange capacity affect plant enrichment and transfer of uranium in the soil. The fern's U enrichment coefficient was only between 0.003 and 0.025, while the moss in Example 1 had an enrichment coefficient of 0.078. The average U enrichment coefficient for plants ranged from 0.0069 to 0.034, and the moss' adsorption of uranium exceeded 5.5 times its average enrichment coefficient. Therefore, moss exhibits excellent tolerance to U and superior U enrichment performance.

[0052] Comparative Example 2

[0053] The difference between this comparative example and Example 1 is that the biochar in the ecological mineral filler unit 4 is replaced by clay; the remaining steps are consistent with Example 1.

[0054] When clay is used to construct the ecological mineral filler unit, the uranium removal rate of the cascade self-driven ecological filter for actual uranium-containing wastewater with an initial uranium concentration of 52 mg / L is only 72.64%. This is because the clay has low porosity and adsorption capacity, high density, slow adsorption rate, and may introduce secondary pollution (such as heavy metal leaching).

[0055] Comparative Example 3

[0056] The difference between this comparative example and Example 1 is that the polyamine / amidoxime polyacrylonitrile fiber (PAN-AO-A) in the functional fiber material filler unit 5 is replaced by an ion chelating functionalized fiber (PAN PA ); The remaining steps are consistent with those in Example 1.

[0057] Ion chelating functionalized fiber (PAN PA ) When constructing a multifunctional fiber material packing unit, the uranium removal rate of the cascade self-driven ecological filter for the actual uranium-containing wastewater with an initial uranium concentration of 52 mg / L was only 90.55%. This is because the ion chelating functional fiber (PAN PA ) only performs well in treating high-concentration uranium-containing wastewater, while the cascade ecological filter built by the present invention treats low-concentration uranium-containing wastewater in the mining area, so the polyamine / amidoxime polyacrylonitrile fiber (PANAO-A) used in the present invention has a higher removal rate for low-concentration uranium-containing wastewater.

[0058] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and examples shown and described herein.

Claims

1. A method for accurately blocking and controlling uranium-containing wastewater in a cascade self-driven ecological filter in a high-altitude and fragile ecological zone, characterized in that: The following steps are involved: Step 1: Collect uranium-containing and polymetallic wastewater and measure its water quality; Step 2: preparing simulated polymetallic wastewater according to the content of metal elements in the uranium-containing polymetallic wastewater; Step 3: Conduct static adsorption tests on simulated polymetallic wastewater using natural ecological minerals, multifunctional fiber materials, and moss plants; Step 4: Build a cascade self-driven ecological filter containing moss plants based on the test results of step 3.

2. The method for accurately blocking and controlling uranium-containing wastewater in a cascade self-driven ecological filter in a high-altitude and fragile ecological zone according to claim 1 is characterized in that: In step 1, uranium-containing polymetallic wastewater is collected from underground seepage water in a uranium mine. When measuring the water body, its pH, dissolved oxygen, TOC, TN, TP and the content of each metal element are measured, including the metal oxidation state, reduction state, residual state and acid solubility state.

3. The method for accurately blocking and controlling uranium-containing wastewater in a cascade self-driven ecological filter in a high-altitude and fragile ecological zone according to claim 1 is characterized in that: In the step 2, the specific method for preparing the simulated polymetallic wastewater is: adding UO2(NO3)2·6H2O, Pb(NO)3, Fe(NO3)2, Mn(NO3)2, and Zn(NO3)2 in a dosage ratio of 50-100 mg:0.1-0.5 mg:5-10 mg:1-10 mg:15-20 mg to 1 L of ultrapure water to prepare simulated uranium mining area polymetallic wastewater.

4. The method for accurately blocking and controlling uranium-containing wastewater in a cascade self-driven ecological filter in a high-altitude and fragile ecological zone according to claim 1 is characterized in that: In step three, the natural ecological mineral is biochar, and the method for conducting a static adsorption test using the natural ecological mineral is as follows: weigh 1 to 2 g of the natural ecological mineral and place it in a 250 mL conical flask, add 100 to 200 mL of simulated multi-metal wastewater, seal it with a sealing film and a rubber band, and culture it in a constant temperature shaking incubator at 25°C for 24 hours. After filtering through a 0.45 micron filter membrane, use an ICP-OES spectrometer to determine the content of heavy metal ions in the filtrate.

5. The method for accurately blocking and controlling uranium-containing wastewater in a cascade self-driven ecological filter in a high-altitude and fragile ecological zone according to claim 1 is characterized in that: In step three, the multifunctional fiber material is polyamine / amidoxime polyacrylonitrile fiber, and the method for conducting a static adsorption test using the multifunctional fiber material is as follows: weigh 0.05-0.1 g of the multifunctional fiber material and place it in a 250 mL conical flask, add 100-200 mL of simulated multi-metal wastewater, seal it with a sealing film and a rubber band, and shake and culture it in a constant temperature shaking incubator at 25°C for 24 hours. After filtering through a 0.45 micron filter membrane, the content of heavy metal ions in the filtrate is determined using an ICP-OES spectrometer.

6. The method for accurately blocking and controlling uranium-containing wastewater in a cascade self-driven ecological filter in a high-altitude and fragile ecological zone according to claim 1, characterized in that: In step three, the specific method for conducting a static adsorption test on simulated multi-metal wastewater using moss plants is as follows: bring moss plants collected from the field back to the laboratory, pick out weeds and soil clods, rinse the dust on the surface of the plants with tap water, and rinse them several times with deionized water to remove the metal ions on the surface; divide the washed moss plants into small pieces of 8×8 cm, place them in a culture pot filled with pine needle matrix for cultivation, regularly add 50 mL of simulated multi-metal wastewater every day, and after culturing for 30 to 60 days, take a certain amount of soil for digestion and determine the metal ion content therein; and calculate the heavy metal ion removal rate.

7. The method for accurately blocking and controlling uranium-containing wastewater in a cascade self-driven ecological filter in a high-altitude and fragile ecological zone according to claim 4, characterized in that: Before conducting the static adsorption test, the biochar was modified: the biochar was soaked in a sodium citrate solution, taken out after being fully soaked, heat-treated in an oxygen-free environment, cooled and then soaked in a sodium hydroxide solution, and finally washed and dried to obtain modified biochar.

8. The method for accurately blocking and controlling uranium-containing wastewater in a cascade self-driven ecological filter in a high-altitude and fragile ecological zone according to claim 7, characterized in that: The concentration of the sodium citrate solution is 0.1-0.5 mol / L, the mass volume ratio of the biochar and the sodium citrate solution is kg / L=1-2:10-15, the heat treatment temperature is 300-400°C, the heat treatment time is 1-2h, the concentration of the sodium hydroxide solution is 2-4 mol / L, and the mass volume ratio of the biochar and the sodium hydroxide solution is kg / L=1-2:5-10.

9. A cascade self-driven ecological filter containing moss plants, characterized in that: It includes a water distribution unit, a flow control unit, a pretreatment unit, an ecological mineral filler unit, a multifunctional fiber material filler unit, a plant growth unit, and a water collection unit, which are sequentially lowered from left to right; the water distribution unit is connected to the pretreatment unit through the flow control unit, and the flow control unit is provided with a valve.

10. The cascade self-driven ecological filter containing moss plants according to claim 9, characterized in that: The ecological mineral filler unit comprises, from bottom to top, quartz sand with a layer height of 150 to 250 mm, biochar with a layer height of 550 to 650 mm, and gravel with a layer height of 150 to 250 mm; the multifunctional fiber material filler unit comprises, from bottom to top, polyamine / amidoxime polyacrylonitrile fiber with a layer height of 550 to 650 mm, a porous plate, and gravel with a layer height of 150 to 250 mm; the plant growth unit comprises, from top to bottom, a moss plant layer, a clay filter layer with a layer height of 400 to 450 mm, a sand and gravel filter layer with a layer height of 50 to 150 mm, and gravel with a layer height of 50 to 150 mm.

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