A treatment method for polluted soil on the slope of the water landscape in a weathered crust eluvial rare earth mining area

Abstract

The invention discloses a method for treating polluted soil on the water landscape slope in a weathered crust eluvial rare earth mining area, belonging to the field of treatment and regeneration of polluted soil. The method of the invention includes constructing a recoverable barrier system for pollutants in the slope rainfall runoff of the soil in the weathered crust eluvial rare earth mining area, a strong reduction treatment system for polluted soil, a bionic transpiration system, the combined application of strong reduction treatment and bionic transpiration, and a valuable substance recovery system. The method of the invention realizes the treatment of both symptoms and root causes of the polluted soil on the water landscape slope in the weathered crust eluvial rare earth mining area, not only treats soil pollution but also prevents the treated soil from being re-polluted by pollutants in the adjacent environment, and can also recover valuable pollutants in the adjacent environment, effectively controls the water flow, evaporation and leakage of the water landscape slope, and realizes the soil environmental conditions beneficial to the improvement and treatment of the polluted soil on the water landscape slope.

Description

Technical Field

[0001] The present invention belongs to the technical field of contaminated soil treatment and regeneration, and particularly relates to a method for treating contaminated soil on a water landscape slope in a weathered crust eluvial rare earth mining area. Background Art

[0002] Weathered crust eluvial rare earth ore is an important mineral resource, which contains relatively more medium and heavy rare earths. At present, the contaminated soil in weathered crust eluvial rare earth mining areas has severely degraded, with soil acidification and low organic matter content. The types of its pollutants are numerous, including pollutants originating from the rare earth ore itself, such as rare earths, heavy metals, aluminum ions, etc.; and pollutants originating from the ore leaching agent of the rare earth ore, such as the pollution of ammonium nitrogen, sulfate, and nitrate caused by ammonium sulfate leaching of the ore. On the other hand, the migration of pollutants in the contaminated soil usually also causes pollution of adjacent water bodies.

[0003] For the treatment of polluted soil in eluvial rare earth ore areas, chemical or biological remediation methods are usually adopted at present, and the treatment is carried out according to the classification of pollutants. For example, chemical remediation methods can be used to stabilize heavy metal ions and rare earth ions in polluted soil respectively. The stabilizing reagents for soil heavy metal ions include clay minerals, lime materials, biochar, organic high-sulfur stabilizers, etc., and the stabilizing reagents for soil rare earth ions include clay minerals, phosphates, etc.; or eluants such as calcium chloride, potassium chloride, sodium chloride, sodium carbonate, potassium carbonate, magnesium sulfate, aluminum sulfate, iron sulfate, citric acid, saponin and sapogenin are used to leach rare earth or ammonia nitrogen in the soil, and then the rare earth or ammonium nitrogen is recovered; or phytoremediation methods are used to plant heavy metal or rare earth hyperaccumulator plants on polluted soil, and the heavy metals or rare earths in the soil are extracted and recovered by the above-ground parts of the plants; or the plants are used to absorb nitrogen and sulfur in the soil to reduce the nitrogen and sulfur pollutants in the polluted soil. Biomimetic trees with transpiration function are occasionally used to treat heavy metal polluted soil, but the method is not mature. In particular, air embolism is likely to occur in the biomimetic xylem of biomimetic trees, resulting in the inability to continuously carry out biomimetic transpiration. However, these soil remediation methods have the following problems: 1. They are only applicable to improving soil fertility or treating one or a class of pollutants, and are often powerless for other soil degradation factors, and even lead to the further enhancement of the effects of other soil degradation factors; 2. Chemical remediation methods will cause the redissolution of passivated pollutants, resulting in secondary pollution; while biological remediation methods are restricted by various limiting conditions for the growth of plants and soil microorganisms, such as temperature, humidity, nutrients, water, redox, sunlight, etc.; biomimetic trees are only applicable to treating some soil heavy metal pollution, and are prone to air embolism and unable to continuously carry out biomimetic transpiration, so they cannot continuously treat polluted soil; these soil remediation methods consume a large amount of labor and energy. For the remediation of polluted soil on the water landscape slope, there are also the following specific problems: 1. The pollutants contained in the polluted soil at a higher horizontal height adjacent to the water landscape slope pollute the soil of the water landscape slope due to migration; 2. The slope and soil properties of the water landscape slope affect the migration and transformation of soil substances, thus indirectly having an adverse impact on the treatment of polluted soil on the water landscape slope. In addition, most of the weathered crust eluvial rare earth ores are hills and mountains. It is difficult to implement strong reduction for this type of soil. On the one hand, this type of soil has a slope, and on the other hand, this type of soil is mostly sandy soil, and it is difficult for water to remain in the soil, and it is not easy to form the waterlogging conditions required to maintain the strong reduction state of the soil, resulting in difficulty in using strong reduction technology to treat this type of polluted soil. Summary of the Invention

[0004] Objective of the Invention: To solve the above technical problems, the present invention provides a method for treating polluted soil on the water landscape slope in the weathered crust eluvial rare earth mining area, which achieves the following objectives: 1. Simultaneously treat multiple pollutants in the polluted soil, stabilize heavy metals in the soil, recover rare earths and ammonium nitrogen in the soil, and at the same time reduce the sulfate and nitrate contents in the soil; and improve the soil, reduce the soil acidity and increase the soil organic matter content. 2. Compared with conventional chemical remediation technologies, it is not easy to cause secondary pollution of certain pollutants; compared with conventional bioremediation technologies, it is not restricted by biological habitat conditions, and also overcomes the problem that the bionic tree itself is prone to air embolism and cannot continuously carry out bionic transpiration and treat polluted soil. 3. Achieve energy conservation, labor saving, short cycle, low cost, high efficiency and simple management for the treatment of polluted soil. 4. Take measures to avoid the re-pollution of the soil on the water landscape slope by pollutants in the adjacent environment; take measures to control the water flow and leakage on the water landscape slope to achieve an environmental condition of strong reduction state of the soil beneficial to the improvement and treatment of polluted soil on the water landscape slope.

[0005] The present invention also provides an application of the method for treating polluted soil on the water landscape slope in the weathered crust eluvial rare earth mining area in treating and regenerating polluted soil on the water landscape slope in the weathered crust eluvial rare earth mining area.

[0006] Technical Solution: To achieve the above objectives, the method for treating polluted soil on the water landscape slope in the weathered crust eluvial rare earth mining area according to the present invention includes a recoverable barrier system for pollutants in the surface rainfall runoff, a strong reduction treatment system for polluted soil, a bionic transpiration system, a combined application of strong reduction treatment and bionic transpiration, and a valuable substance recovery system;

[0007] Specifically, it includes the following steps:

[0008] S1. Construct a recoverable barrier system for pollutants in the surface rainfall runoff of polluted soil on the water landscape slope in the weathered crust eluvial rare earth mining area to block pollutants transferred into the runoff in a water-soluble or particulate state due to the scouring of the polluted soil on the slope surface;

[0009] S2. Construct a strong reduction treatment system for polluted soil on the water landscape slope in the weathered crust eluvial rare earth mining area, transform the water landscape slope of the rare earth mining area to be treated into gentle slope terraces, and conduct strong reduction treatment on the polluted soil;

[0010] S3. Construct a bionic transpiration system, and implant bionic trees capable of carrying out bionic transpiration in the polluted soil treated by strong reduction in step S2;

[0011] S4. Set up a greenhouse above the polluted soil treated by strong reduction and the bionic trees, implement the combined application of soil strong reduction and bionic transpiration and valuable substance recovery, and recover rare earths and ammonium nitrogen from the bionic tree leaves.

[0012] Furthermore, in step S1, the method for constructing a recoverable barrier system for pollutants in the slope rainfall runoff of polluted soil in the water landscape slope of the weathering crust leaching type rare earth mining area is:

[0013] (1) digging a ridgeless earth pit in the left and right directions at the upper edge of the horizontal height of the water landscape slope of the weathered crust eluvial rare earth mining area to be treated, as the boundary between the upstream polluted slope of the slope rainfall runoff and the downstream slope to be treated; the horizontal height is set according to the conditions of the polluted slope to be treated, and if necessary, a number of repeated ridgeless earth pit units are set to ensure that the ridgeless earth pit or ridgeless earth pit unit is dug in the left and right directions along the contour line, with a rectangular cross-section, a depth of 0.75-1.5m, and a width of 2.1-2.9m; wherein the set horizontal height refers to the upper horizontal edge of the polluted slope to be treated after it is determined; the ridgeless earth pit is dug in the left and right directions along the contour line;

[0014] (2) Adsorption bags are piled on one side of the soil pit without ridges connected to the polluted slope upstream of the slope runoff. The width of the adsorption bags is 1.6-2.4m. The middle part of the upper part of the adsorption bag pile is parallel to the slope surface in the horizontal direction to leave a left and right ditch. The top plane of the tail of the adsorption bag pile is 0.25-0.5m higher than the top plane of the head of the adsorption bag pile. The head of the adsorption bag pile is connected to the polluted slope upstream of the slope runoff.

[0015] (3) There is a 0.5-0.8m gap between the tail of the adsorption bag stack in the pit without ridges and the downstream slope to be treated. Montmorillonite or uncontaminated guest soil is filled in to form a recoverable barrier system for pollutants in slope rainfall runoff with a depth of 0.2-0.4m. The lower edge of the left and right drainage ditches are connected to one side of the downstream slope to be treated. The downstream slope to be treated is the slope to be treated downstream of the slope rainfall runoff.

[0016] Furthermore, in step (2), part of the adsorption bags are adsorption bags filled with anion exchange resin, and the other part are adsorption bags filled with cation exchange resin. The adsorption bags are stacked in order so that when the slope rainfall runoff flows through the adsorption bags, it first contacts only the adsorption bags filled with anion exchange resin to perform anion exchange; after the slope rainfall runoff flows through the adsorption bags filled with anion exchange resin, it contacts the adsorption bags filled with cation exchange resin to perform cation exchange.

[0017] Furthermore, in step S2, the method for constructing a strong reduction treatment system for polluted soil on a water landscape slope in a weathering crust leaching type rare earth mining area is:

[0018] (4) At the lower edge of the left-right drainage soil ditch at the lower edge of the recyclable barrier system for pollutants in the slope rainfall runoff, and at the polluted soil on the slope of the downstream slope to be treated that is adjacent to the drainage soil ditch, dig soil and build ridges at the same horizontal height; along the slope direction of the downstream slope to be treated, set the horizontal height according to the conditions of the slope to be treated, and dig several drainage soil ditches or multiple drainage soil ditch units. The drainage soil ditches are left-right oriented, forming drainage soil ditches with a width of 0.4 - 0.6 m and a depth of 0.2 - 0.4 m. After the drainage soil ditches are filled with montmorillonite or uncontaminated borrowed soil, build soil ridges at the polluted soil on the slope of the downstream slope to be treated that is adjacent to both sides of the drainage soil ditches respectively; between the lower edge soil ridge of the drainage soil ditch at each horizontal height and the upper edge soil ridge of the drainage soil ditch at the next horizontal height, dig the soil pit between the ridges. Above the unit formed by each soil pit between the ridges and the soil ridges on both sides, lay the bottom-laid soil anti-seepage membrane integrally, and then backfill the polluted soil dug from the soil pit between the ridges onto the bottom-laid anti-seepage membrane above the soil pit between the ridges, and level the land;

[0019] (5) Add easily degradable organic materials to the backfilled polluted soil after leveling and mix evenly, flood it, and lay the upper covering membrane for strong reduction treatment of the soil above the unit formed by each soil pit between the ridges and the soil ridges on both sides to construct a strong reduction treatment system for the backfilled polluted soil, and then carry out strong reduction treatment.

[0020] Further, the depth of the soil pit between the ridges in step (4) is 0.75 - 1.5 m, and the width is 1.3 - 2.6 m; the height of the soil ridge is 0.4 - 0.6 m, and the width is 0.3 - 0.4 m; the period of the strong reduction treatment in step (5) is 2 - 4 weeks. Small holes for planting bionic trees are arranged at equal distances on the upper covering membranes of the soil ridges and the soil pits between the ridges, with a hole diameter of 5 - 10 cm and a center distance of 30 - 50 cm between the small holes.

[0021] Further, the method for implanting the bionic tree for bionic transpiration in step S3 includes the following steps:

[0022] (6) Assemble the bionic xylem and its hard shell of the bionic tree root system, and the bionic phloem and its hard shell of the bionic tree root system into the bionic tree root system part; assemble the bionic xylem and its hard shell of the bionic tree leaves, and the bionic phloem and its hard shell of the bionic tree leaves into the bionic tree leaf part; there are connecting parts between the bionic phloem and the bionic xylem. Set horizontal connecting parts on the bionic tree root system and vertical connecting parts on the bionic tree leaves to keep them connected; the connecting parts are provided with one-way valves controlled by hinge hinges, which can be replenished with water by the bionic phloem when each bionic xylem is short of water to avoid embolism in the bionic xylem; at the upper end opening of the bionic phloem of the bionic tree leaves, insert a graduated float for indicating the water level, which can show the upper edge condition of the water level in the bionic phloem;

[0023] (7) When the polluted soil is backfilled onto the underlying soil impermeable membrane in the soil pit between the ridges in step (4) of constructing the strong reduction treatment system for polluted soil, the assembled bionic tree root system is buried in the soil, and then flooding is carried out and the upper covering film is laid. The upper end of the bionic tree root system passes through the planting holes provided on the upper covering film; then the gap between the upper covering film and the bionic tree root system is sealed to prevent gas escape;

[0024] (8) Connect the assembled bionic tree leaves to the assembled bionic tree root system.

[0025] Further, the bionic xylem of the bionic tree leaf is arranged above the space enclosed by the edge of the bionic phloem of the bionic tree leaf; a pore channel is provided in the center of the bionic phloem of the bionic tree leaf, and the bionic xylem of the bionic tree root system passes through the bionic phloem of the bionic tree leaf through this pore channel and is directly connected to the bionic xylem of the bionic tree leaf;

[0026] The diameter of the bionic tree leaf is 20 - 40 cm, the diameter of the bionic tree root system is 3 - 8 cm, and the height of the bionic tree root system is 20 - 40 cm; the hard outer shells of the bionic tree leaf and the root system are both made of plastic, separated into bionic xylem space and bionic phloem space, and filled with bionic xylem and bionic phloem materials respectively;

[0027] The bionic xylem and bionic phloem materials can be the same or different, such as filter paper, gauze, etc., which have capillary pores and can undergo capillary action; at the upper opening of the bionic phloem of the bionic tree leaf, a water level display float can be inserted, which is a graduated float for indicating the water level;

[0028] The diameter of the float is 1 cm, the material is foam plastic, the upper end of the float is connected to a wooden rod with a diameter of 0.5 cm, and there are scales on the wooden rod, which can display the upper edge condition of the water level in the bionic phloem of the bionic tree leaf;

[0029] On the hard outer shell on one side of the bionic xylem of the bionic tree root system, an inlet is provided every 5 - 10 cm to enable the soil solution to enter the bionic xylem of the bionic tree root system; the bionic xylem of the bionic tree leaf and its hard outer shell are open to the air upward for transpiration;

[0030] Between the bionic xylem and bionic phloem of the bionic tree leaf, a series of connecting parts are arranged vertically every 5 - 10 cm; between the bionic xylem and bionic phloem of the bionic tree root system, a series of connecting parts are arranged horizontally every 5 - 10 cm; the bionic phloem is provided with a part for placing the graduated float for indicating the water level, and at the same time, the bionic phloem of the bionic tree leaf and its hard outer shell are provided with parts through which water can be injected from the outside;

[0031] The connecting parts between the bionic xylem and bionic phloem of the bionic tree leaves, as well as the connecting parts between the bionic xylem and bionic phloem of the bionic tree roots and stems, are all tubular connections with a length of 0.5 - 1 cm and a diameter of 0.5 - 1 cm. A one-way valve is provided in the tubular connection. The one-way valve is fixed and controlled by a hinge, so that the opening angle of the one-way valve is less than 30°. The one-way valve opens when the bionic xylem cannot effectively obtain water from the soil and the water pressure is too high. At this time, water flows from the bionic phloem to the bionic xylem to supplement water and prevent the formation of embolisms in the bionic xylem.

[0032] Furthermore, the bionic xylem of the bionic tree roots and stems is directly connected to the bionic xylem of the bionic tree leaves. During transpiration, capillary action pulls the soil solution into the bionic xylem of the bionic tree roots and stems, and then into the bionic xylem of the bionic tree leaves; the bionic phloem of the bionic tree roots and stems is directly connected to the bionic phloem of the bionic tree leaves. The water injected into the bionic phloem of the bionic tree leaves can enter the bionic phloem of the bionic tree roots and stems due to gravity. At the same time, the connecting parts between the bionic xylem and bionic phloem of the bionic tree leaves and the connecting parts between the bionic xylem and bionic phloem of the bionic tree roots and stems are all tubular connections. A one-way valve is provided in the tubular connection. When the bionic xylem of the bionic tree leaves loses water excessively, the water injected into the bionic phloem of the bionic tree leaves can flow unidirectionally through the one-way valve into the bionic xylem of the bionic tree leaves, thus avoiding the embolism phenomenon that may occur when the bionic xylem of the bionic tree leaves loses water excessively during bionic transpiration; and the water in the bionic phloem of the bionic tree roots and stems, when the bionic xylem of the bionic tree roots and stems loses water excessively, flows unidirectionally through the one-way valve into the bionic xylem of the bionic tree roots and stems, thus avoiding the embolism phenomenon that may occur when the bionic xylem of the bionic tree roots and stems loses water excessively during bionic transpiration.

[0033] Furthermore, in step S4, the greenhouse built is a simple greenhouse with a fresh air exchange window; The combined application of implementing soil strong reduction, bionic transpiration and valuable substance recovery, and recovering rare earths and ammonium nitrogen from bionic tree leaves includes the following steps:

[0034] (9) A simple greenhouse with a fresh air exchange window is built above the strongly reduced polluted soil and the bionic tree. The fresh air exchange window heats the gas entering the greenhouse through a sensible heat exchange system, and recovers the condensed water in the exhaust gas outside the greenhouse to a high-level water storage tank;

[0035] (10) Rare earth ions and ammonium nitrogen in the soil solution enter the leaves of the bionic tree through the bionic xylem in the bionic tree roots and stems and leaves, and are concentrated as the water evaporates; The rare earths and ammonium nitrogen in the bionic tree leaves are leached with the EDTA solution in the high-level water tank and recovered;

[0036] After the treatment of the polluted soil dug out from the soil pits between the ridges on the sloping land of the water landscape in the weathered crust eluvial rare earth mining area (11), the above-mentioned recyclable barrier system is maintained; the simple greenhouse, the upper covering film and the lower anti-seepage film are removed, and the treated soil in the original soil pits between the ridges is piled up from the upper and lower edges of the original horizontal height of the soil pits between the ridges to the midline of the horizontal height to form a new soil ridge; the untreated soil of the original soil ridge on the sloping land of the water landscape in the above-mentioned rare earth mining area is dug out to form a new soil pit between the ridges; in the new soil pit between the ridges, the above-mentioned strong reduction and biomimetic transpiration schemes are also used to treat the soil.

[0037] Further, the sloping land of the water landscape in the weathered crust eluvial rare earth mining area is a sloping land of the water landscape with a slope less than 25°, and the gentle slope terraced field is a gentle slope terraced field with a slope less than 10°.

[0038] Application of the method for treating polluted soil on the sloping land of the water landscape in the weathered crust eluvial rare earth mining area of the present invention in treating and regenerating polluted soil on the sloping land of the water landscape in the weathered crust eluvial rare earth mining area.

[0039] Preferably, the method for treating polluted soil on the sloping land of the water landscape in the weathered crust eluvial rare earth mining area specifically includes the following steps:

[0040] S1. According to the characteristics that the weathered crust eluvial rare earth ore is mostly on the sloping land of the water landscape, a recyclable barrier system for pollutants in the surface rainfall runoff of the soil on the slope to be treated is constructed. While blocking pollution, the special function of recovering valuable substances is realized by using ion exchange resin.

[0041] S2. According to the characteristics that the weathered crust eluvial rare earth ore is mostly on the sloping land of the water landscape, a strong reduction treatment system for polluted soil on the sloping land is constructed for the first time. The sloping land of the water landscape in the rare earth mining area to be treated is transformed into gentle slope terraced fields, and the polluted soil is subjected to strong reduction treatment.

[0042] S3. A biomimetic transpiration system is constructed, and biomimetic trees capable of performing biomimetic transpiration are implanted in the polluted soil treated by strong reduction in step S2, realizing the special function of directly recovering valuable substances under strong reduction conditions.

[0043] S4. A greenhouse is built above the polluted soil treated by strong reduction and the biomimetic trees to implement soil strong reduction and biomimetic transpiration, and rare earth and ammonium nitrogen are recovered from the leaves of the biomimetic trees, and the combined application of strong reduction treatment and biomimetic transpiration and the recovery of valuable substances are implemented. Among them, the elements in rare earth refer to 14 lanthanide elements except promethium, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y.

[0044] Preferably, a part of the adsorption bag is filled with an anion exchange resin (styrene-based strong base anion exchange resin [Purolite A520E]), and the other part is filled with a cation exchange resin (AG50W-X8 ion exchange resin). The upper covering film and the lower anti-seepage film are made of polyethylene film. The anti-seepage film is underwater, and the upper covering film is used to isolate air.

[0045] Furthermore, in the treatment method, the ionic pollutants in the slope rainfall runoff seep into the adsorption bag and are adsorbed onto the anion or cation exchange resin in the adsorption bag through the anion exchange adsorption or cation adsorption process. Subsequently, rare earth, nitrogen, and sulfur are desorbed and recovered, and the ion exchange resin is regenerated. The particulate pollutants in the slope rainfall runoff are deposited in the left-right ditch reserved horizontally parallel to the slope at the middle upper part of the stacked adsorption bags. After collecting and storing a sufficient amount of sediment, it is placed in the treatment system of the present invention that combines strong reduction treatment and biomimetic transpiration technology and is treated according to the method of the present invention.

[0046] Among them, the slope rainfall runoff is the runoff flowing from a higher horizontal height to a lower height on the slope, carrying pollutants such as rare earth, heavy metals, nitrogen, and sulfur. The gentle slope terrace is a terrace that has been transformed, equipped with soil ridges and drainage soil ditches, and has a slope smaller than the original slope. The biomimetic transpiration is carried out by the biomimetic tree under sunlight irradiation. The biomimetic xylem of the biomimetic tree contains a rich vertical capillary structure, and the biomimetic tree leaves of the biomimetic tree contain a rich horizontal capillary structure. The valuable substances are mainly rare earth elements.

[0047] The present invention constructs a strong reduction treatment system to effectively reduce the pollution levels of sulfates and nitrates in the soil contaminated by the water landscape in the weathered crust elution-type rare earth mining area, effectively reduce the toxicity of hexavalent chromium in the soil, so that the heavy metals in the polluted soil are effectively passivated and their bioavailability is reduced; convert the tetravalent cerium in the soil into trivalent cerium that is easy to migrate, effectively reduce the soil acidity and soil aluminum ion concentration, and improve the physical and chemical properties of the soil.

[0048] Among them, the biomimetic tree leaves undergo biomimetic transpiration and lose water under light conditions, pulling the soil solution into the biomimetic tree root system and transporting it upward along the biomimetic xylem of the biomimetic root system to the biomimetic xylem of the biomimetic tree leaves through capillary action. The biomimetic phloem always remains filled with water and is connected to the biomimetic xylem, using a one-way valve to avoid the possible embolism phenomenon in the biomimetic xylem during biomimetic transpiration. The soil solution containing pollutants such as rare earth and ammonium nitrogen is continuously migrated out of the polluted soil and into the biomimetic tree leaves under the biomimetic transpiration of the biomimetic tree.

[0049] The present invention relates to a method for treating polluted soil on the water landscape slope in a weathered crust eluvial rare earth mining area, which includes a recoverable barrier system for pollutants in surface rainfall runoff, a strong reduction treatment system for polluted soil, a bionic transpiration system, and a combined application of strong reduction treatment and bionic transpiration technology and a valuable substance recovery system.

[0050] Invention mechanism:

[0051] 1. The recoverable barrier system for pollutants in surface rainfall runoff, the design principle of the invention is based on:

[0052] 1-1. The ionic pollutants in surface rainfall runoff penetrate into the adsorption bag, and through the anion exchange adsorption or cation adsorption process, they are adsorbed on the anion or cation exchange resin in the adsorption bag, thereby solidifying the ionic pollutants and preventing their re-pollution of the treated soil; this belongs to a commonly used method in soil pollution treatment. However, the subsequent targeted desorption and recovery of rare earth, nitrogen, and sulfur in the present invention are not the conventional operations of soil solidification technology. In the present invention, on rare earth polluted soil, the recovery of valuable substances such as rare earth is effectively realized, and the ion exchange resin is regenerated.

[0053] 1-2. The particulate pollutants in surface rainfall runoff in the present invention are deposited in the left-right ditch left horizontally parallel to the slope at the upper middle part of the adsorption bag stack. After collecting and storing a sufficient amount of sediment, it is placed in the treatment system that combines strong reduction treatment and bionic transpiration technology of the present invention to recover valuable substances such as rare earth. This is not the conventional operation of soil pollution control technology. On rare earth polluted soil, the recovery of valuable substances such as rare earth can be effectively realized.

[0054] 2. The technical solution of the strong reduction treatment of polluted soil in the weathered crust eluvial rare earth mining area of the present invention, the design principle of the invention is based on:

[0055] 2-1. Usually, strong reduction treatment of soil is carried out on flat plots. It is difficult to flood the slope land, and the water on the slope land is easy to form runoff and flow away; at the same time, it is difficult for sandy soil to retain water and it is not easy to form a flooded condition. Most weathered crust eluvial rare earth mines are hilly and mountainous areas. It is difficult to implement strong reduction on such soil because the soil has a slope, and the water required to maintain the flooded state of the strongly reduced soil is difficult to retain in the soil. At the same time, the soil is mostly sandy soil and it is not easy to retain water. The present invention designs to use a method similar to terraced fields to solve the problem of runoff loss of slope soil water; at the same time, by using the method of laying anti-seepage membranes, the problem of water leakage in sandy soil is solved, and effective soil strong reduction is realized. Usually, the polluted soil in rare earth mining areas belongs to sandy loam, and there is a certain slope in the soil of rare earth mining areas, making it difficult to maintain a flooded state and difficult to realize strong reduction treatment of the soil; the technical solution of the present invention adopts measures such as transforming into terraced fields, building ridges, and laying anti-seepage membranes below, which can effectively maintain soil water storage and realize strong reduction treatment of the soil.

[0056] 2-2. The redox potential of the soil can be as low as -200 mV, and the system can effectively reduce tetravalent cerium (Ce(IV)+e→Ce 3+ , 1.72 V), hexavalent chromium (Cr(VI)+3e→Cr 3+ , 1.33 V), pentavalent arsenic (As(V)+2e→As(III), 0.56 V). For the soil treated by strong reduction, if the selected organic material has a high sulfur content, a large amount of sulfide ions can be generated through reduction and form precipitates with heavy metal ions in the soil, which can stabilize heavy metals in the soil. Generally, heavy metal ions belong to soft acids and are prone to coordinate with sulfide ions, which belong to soft bases, to form precipitates. In this way, for heavy metal ions and rare earth ions, obvious differences in results occur in the strong reduction system: soft acid heavy metal ions form precipitates with sulfide ions and are stabilized and treated in the soil; rare earth ions and Cr 3+ belong to hard acids and are not prone to coordinate with sulfide ions, which belong to soft bases. They are not solidified in the soil, still remain effective, are easy to migrate out of the polluted soil and be recovered. Different from the existing soil pollution treatment, the present invention only recovers some specific valuable substances in the mining area soil; on the rare earth polluted soil, the recovery of valuable substances such as rare earth is effectively realized, the heavy metals are effectively solidified, and the separation of rare earth from heavy metals is realized.

[0057] 3. The biomimetic transpiration of the biomimetic tree in the present invention is based on the following invention principle:

[0058] 3-1. For the biomimetic transpiration of the biomimetic tree, solar energy is utilized to cause the evaporation of water on the leaves of the biomimetic tree, generating a negative water potential; this method is commonly used to obtain water and substances in the soil solution. The technical difficulty in the prior art is that part or all of the biomimetic xylem will generate air embolism due to water loss and it is difficult to continuously maintain biomimetic transpiration; the present invention adopts biomimetic phloem to effectively supply water to the biomimetic xylem to avoid embolism and achieve continuous biomimetic transpiration.

[0059] 3-2. For a general biomimetic tree, the solution in the leaf part of the biomimetic tree is recovered by gravity. In this way, if the biomimetic transpiration is intense, the water potential of the solution in the leaves of the biomimetic tree is relatively negative and it is difficult to recover; if the biomimetic transpiration is not intense, it is difficult to lift the soil solution to the leaves of the biomimetic tree. The present invention builds a simple greenhouse equipped with a fresh air exchange window above the soil treated by strong reduction and the biomimetic tree. The fresh air exchange window heats the gas entering the greenhouse through sensible heat exchange and recovers the condensed water in the exhaust gas outside the greenhouse to a high-level water tank. The water in the high-level water tank is regularly made into an EDTA solution with a certain concentration to wash the rare earth and ammonium nitrogen in the leaves of the biomimetic tree and recover them, which can effectively realize the combined treatment of the strong reduction treatment of the polluted soil on the water landscape slope of the weathered crust eluvial rare earth mining area and the biomimetic transpiration technology.

[0060] The treatment method of jointly applying strong reduction treatment and bionic transpiration technology to the polluted soil on the water landscape slope in the weathered crust eluvial rare earth mining area of the present invention can simultaneously treat the pollution of rare earth, heavy metals, nitrogen, and sulfur in the polluted soil on the water landscape slope in the weathered crust eluvial rare earth mining area, recover the rare earth and ammonium nitrogen therein, and improve the soil. Compared with the conventional chemical remediation technology, the present invention is not likely to cause secondary pollution of certain pollutants. Compared with the conventional bioremediation technology, the present invention is not restricted by biological habitat conditions, and also overcomes the problem that the bionic tree itself is prone to air embolism and cannot continuously carry out bionic transpiration and treat polluted soil. It realizes the treatment of polluted soil with energy saving by using solar energy, short cycle, labor saving, low cost, high efficiency, and simple management.

[0061] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0062] 1. The treatment method of the present invention realizes the treatment of both the symptoms and root causes of the polluted soil on the water landscape slope in the weathered crust eluvial rare earth mining area. It not only treats soil pollution and improves the soil, but also prevents the treated soil from being re-polluted by pollutants in the adjacent environment, and can also recover valuable pollutants in the adjacent environment. The method of the present invention can effectively control the water flow, evaporation, and leakage of the water landscape slope, implement strong reduction of the soil, and contribute to realizing the soil environmental conditions beneficial to the improvement and treatment of the polluted soil on the water landscape slope.

[0063] 2. The treatment method of the present invention simultaneously treats multiple pollutants in the polluted soil, stabilizes the heavy metals in the soil, recovers the rare earth and ammonium nitrogen in the soil, and reduces the sulfate and nitrate contents in the soil; in addition, it also improves the soil, reduces the soil acidity, and increases the soil organic matter content.

[0064] 3. The treatment method of the present invention avoids the secondary pollution of certain pollutants that may be caused by the soil chemical remediation technology, such as removing rare earth elements from the soil; it avoids the demanding requirements of the soil bioremediation technology for the habitat, such as temperature, humidity, nutrients, water, redox, sunlight, etc.; it enables the bionic tree to be applicable to the co-existing pollution of multiple pollutants in the polluted soil in the rare earth mining area, and avoids the bionic tree from having air embolism and being unable to continuously carry out bionic transpiration and treat polluted soil.

[0065] 4. The treatment method of the present invention realizes the treatment and regeneration of polluted soil with energy saving by using solar energy, labor saving, short cycle, low cost, high efficiency, and simple management. Description of the Drawings

[0066] Figure 1Stereo structure diagram of weathering crust eluvial rare earth ore mine and small watershed provided by the embodiment of the present invention, wherein: 1 - mountaintop of the mine; 2 - hillside; 3 - implementation area of the barrier and recovery system; 4 - implementation area of the combined treatment of strong reduction treatment and bionic transpiration; 5 - water landscape slope; 6 - riverbed; 7 - river water.

[0067] Figure 2 Structural diagram of the recoverable barrier system for pollutants in slope rainfall runoff constructed by the embodiment of the present invention, wherein: 8 - mine on the upper edge of the recoverable barrier system; 9 - runoff flowing downward from the mountaintop of the mine; 10 - adsorption bag filled with anion exchange resin; 11 - adsorption bag filled with cation exchange resin; 12 - drainage soil ditch; 13 - montmorillonite or uncontaminated borrow soil; 14 - water landscape slope area where the combined treatment of strong reduction treatment and bionic transpiration is implemented.

[0068] Figure 3 Schematic diagram of the strong reduction treatment of soil constructed by the embodiment of the present invention, wherein: 12 - drainage soil ditch; 13 - montmorillonite or uncontaminated borrow soil; 15 - gentle slope step field; 16 - upper film; 17 - lower laid soil anti-seepage membrane; 18 - soil ridge; 19 - soil pit between ridges; 20 - backfilled polluted soil; 21 - soil-water interface; 22 - flooding.

[0069] Figure 4 Schematic diagram of the bionic tree constructed by the embodiment of the present invention, wherein: 23 - bionic tree leaf; 24 - connection part between the bionic tree leaf and the bionic tree root; 25 - bionic tree root; 26 - bionic phloem of the bionic tree leaf; 27 - bionic xylem of the bionic tree leaf; 28 - bionic phloem of the bionic tree root; 29 - bionic xylem of the bionic tree root; 30 - hard shell of the bionic xylem of the bionic tree root; 31 - hard shell of the bionic xylem of the bionic tree leaf; 32 - hard shell of the bionic phloem of the bionic tree root; 33 - hard shell of the bionic phloem of the bionic tree leaf.

[0070] Figure 5 Top view of the bionic tree constructed by the embodiment of the present invention, wherein: 24 - connection part between the bionic tree leaf and the bionic tree root; 26 - bionic phloem of the bionic tree leaf; 27 - bionic xylem of the bionic tree leaf; 31 - hard shell of the bionic xylem of the bionic tree leaf; 33 - hard shell of the bionic phloem of the bionic tree leaf.

[0071] Figure 6Cross-sectional view of the bionic tree constructed for the embodiments of the present invention, where: 21 - soil-water interface; 24 - connection part between the bionic tree leaf and the bionic tree rootstock; 26 - bionic phloem of the bionic tree leaf; 27 - bionic xylem of the bionic tree leaf; 28 - bionic phloem of the bionic tree rootstock; 29 - bionic xylem of the bionic tree rootstock; 30 - hard outer shell of the bionic xylem of the bionic tree rootstock; 31 - hard outer shell of the bionic xylem of the bionic tree leaf; 32 - hard outer shell of the bionic phloem of the bionic tree rootstock; 33 - hard outer shell of the bionic phloem of the bionic tree leaf; 34 - graduated float indicating water level; 35 - connection part between the bionic xylem and the bionic phloem of the bionic tree leaf; 36 - connection part between the bionic xylem and the bionic phloem of the bionic tree rootstock; 37 - soil solution.

[0072] Figure 7 Schematic diagram of the connection part between the bionic xylem and the bionic phloem constructed for the embodiments of the present invention, where: 26 - bionic phloem of the bionic tree leaf; 27 - bionic xylem of the bionic tree leaf; 28 - bionic phloem of the bionic tree rootstock; 29 - bionic xylem of the bionic tree rootstock; 35 - connection part between the bionic xylem and the bionic phloem of the bionic tree leaf; 36 - connection part between the bionic xylem and the bionic phloem of the bionic tree rootstock; 38 - one-way valve; 39 - hinge.

[0073] Figure 8 Schematic diagram of the combined treatment system of strong reduction treatment and bionic transpiration for the polluted soil on the water landscape slope in the weathered crust eluvial rare earth ore area of the embodiments of the present invention; where: 16 - upper film; 17 - bottom-laid soil anti-seepage membrane; 18 - soil ridge; 20 - backfilled polluted soil; 21 - soil-water interface; 22 - flooding; 23 - bionic tree leaf; 25 - bionic tree rootstock; 40 - simple greenhouse; 41 - greenhouse film.

[0074] Figure 9 Schematic diagram of implanting a bionic tree at the upper film of the strong reduction treatment for the embodiments of the present invention, where: 16 - upper film; 25 - bionic tree rootstock; 42 - planting hole; 43 - sealing tape paper.

[0075] Figure 10 Schematic diagram of the greenhouse for the embodiments of the present invention, where: 23 - bionic tree leaf; 44 - ventilation system; 45 - exhaust system; 46 - intake system; 47 - condensate water; 48 - sensible heat exchange system; 49 - high-level water tank; 50 - EDTA solution; 51 - water pipe; 52 - concentrated solution recovery system. Detailed implementation manners

[0076] The present invention will be further described below in conjunction with the embodiments and the drawings.

[0077] Embodiment 1

[0078] The present embodiment provides a treatment system for contaminated soil on water landscape slopes in weathering crust leaching rare earth mining areas by combined application of strong reduction treatment and bionic transpiration technology, including construction of a recoverable barrier system for pollutants in slope rainfall runoff, a strong reduction treatment system for contaminated soil, a bionic transpiration system, a combined application of strong reduction treatment and bionic transpiration technology, and a valuable substance recovery system.

[0079] Among them, the water landscape slopes in the weathering crust elution type rare earth mining area, such as Figure 1 As shown in the figure, the three-dimensional structure diagram of the weathering crust elution type rare earth mine and small watershed, the mountain from top to bottom are: mine mountain top 1, hillside 2, water landscape slope 5, riverbed 6, river water 7. Water landscape slope 5 is a water landscape slope with a slope of less than 25°, including the barrier and recovery system implementation area 3 and the strong reduction treatment and bionic transpiration joint management implementation area 4. The barrier and recovery system implementation area 3 is transformed into a barrier system space for the recovery of pollutants in the slope rainfall runoff, and the strong reduction treatment and bionic transpiration joint management implementation area 4 is transformed into a gentle slope terrace space with an angle of less than 10°, to isolate and recover pollutants carried by the slope rainfall runoff from the mine 8 on the upper edge of the recyclable barrier system ( Figure 2 ).

[0080] like Figure 2 As shown, a ridgeless earth pit with a depth of 0.75-1.5m is dug horizontally parallel to the slope surface in the left and right directions. The upper edge of the ridgeless earth pit is connected to the upstream slope of the slope rainfall runoff, serving as the boundary between the upstream polluted slope of the slope rainfall runoff and the downstream slope of the slope rainfall runoff (the downstream slope to be treated). Several layers of adsorption bags 11 filled with cation exchange resin (AG50W-X8 ion exchange resin) are stacked in order at the bottom of the ridgeless earth pit, and adsorption bags 10 filled with anion exchange resin (styrene-based strong base anion exchange resin [PuroliteA520E]) are stacked above the several layers of adsorption bags 11 filled with cation exchange resin and on the front end surface. The adsorption bags 10 filled with anion exchange resin are closer to the upstream polluted slope of the slope rainfall runoff. The runoff 9 flowing downward from the top of the mine mountain flows through the adsorption bag, and first contacts only the adsorption bag 10 filled with anion exchange resin to perform anion exchange; after the runoff flows through the adsorption bag 10 filled with anion exchange resin, it contacts the adsorption bag 11 filled with cation exchange resin to perform cation exchange.

[0081] Among them, the top plane of the tail of the adsorption bag stack is higher than the top plane of the head of the adsorption bag stack to control the flow velocity of the water flow in the up-down direction. The head of the adsorption bag 10 filled with anion exchange resin is connected to the polluted slope on one side of the upstream of the slope rainfall runoff. There is a 0.5 - 0.8 m gap between the tail of the adsorption bag 11 filled with cation exchange resin stacked in the soil pit without a ridge and the downstream slope to be treated. A certain amount of montmorillonite or uncontaminated borrowed soil 13 is filled in to form a left-right drainage soil ditch 12 in the horizontal direction and parallel to the slope. The drainage soil ditch 12 can recover the pollutants at the lower edge of the barrier system and is connected as a whole with one side of the water landscape slope area 14 implemented by the combined treatment of strong reduction treatment and bionic transpiration of the downstream slope to be treated.

[0082] As Figure 3 shown in the strong reduction treatment and bionic transpiration combined treatment implementation area 4 constructed by the present invention. The strong reduction treatment system for polluted soil includes a gentle slope first terraced field 15 transformed from a water landscape slope. The upper edge of the horizontal height of the gentle slope first terraced field 15 is in contact with the drainage soil ditch 12, and the drainage soil ditch 12 is filled with montmorillonite or uncontaminated borrowed soil 13.

[0083] At several set horizontal heights in the direction along the slope of the gentle slope first terraced field 15, a left-right drainage soil ditch 12 is constructed, and earth ridges 18 are formed on both sides of the drainage soil ditch 12. Between the earth ridge 18 at the lower edge of the drainage soil ditch 12 constructed at each horizontal height and the earth ridge 18 at the upper edge of the drainage soil ditch 12 constructed at the next horizontal height, an inter-ridge soil pit 19 is dug. The inter-ridge soil pit 19 and the earth ridges 18 on both sides are all laid with a bottom-laid soil anti-seepage membrane 17, and then the polluted soil 20 (i.e., the excavated soil is backfilled) is supplemented and backfilled on the bottom-laid soil anti-seepage membrane 17, the land is leveled, and an easily degradable organic material (one or several of crop straws, organic fertilizers subjected to a certain degree of fermentation treatment, or green manure) is added and mixed evenly, and then flooded 22 and covered to form a soil-water interface 21. Finally, an upper covering membrane 16 for soil strong reduction treatment is covered above the unit formed by each inter-ridge soil pit 19 and the earth ridges 18 on both sides to form a soil strong reduction treatment system.

[0084] The bionic transpiration system is located in the strong reduction treatment and bionic transpiration combined treatment implementation area 4 and is arranged above the strong reduction treatment system for polluted soil. As Figure 4 、 Figure 5As shown in the figure, the bionic tree is composed of bionic tree leaves 23, the connection part 24 between the bionic tree leaves and the bionic tree rootstock, and the bionic tree rootstock 25. The bionic tree leaves 23 are composed of the bionic phloem 26 of the bionic tree leaves, the bionic xylem 27 of the bionic tree leaves, the hard shell 31 of the bionic xylem of the bionic tree leaves, and the hard shell 33 of the bionic phloem of the bionic tree leaves; the bionic tree rootstock is composed of the bionic phloem 28 of the bionic tree rootstock, the bionic xylem 29 of the bionic tree rootstock, the hard shell 30 of the bionic xylem of the bionic tree rootstock, and the hard shell 32 of the bionic phloem of the bionic tree rootstock. The bionic xylem of the bionic tree is used to transport water upward, and is directly connected by the bionic xylem 29 of the bionic tree rootstock and the bionic xylem 27 of the bionic tree leaves; the bionic phloem of the bionic tree is used to prevent the formation of xylem embolism, and is directly connected by the bionic phloem 28 of the bionic tree rootstock and the bionic phloem 26 of the bionic tree leaves.

[0085] As Figure 5 , Figure 6 shown, the bionic xylem 27 of the bionic tree leaves is arranged above the space enclosed by the edge of the bionic phloem 26 of the bionic tree leaves; a pore is provided in the center of the bionic phloem 26 of the bionic tree leaves, and the bionic xylem 29 of the bionic tree rootstock passes through the bionic phloem 26 of the bionic tree leaves through this pore and is directly connected to the bionic xylem 27 of the bionic tree leaves.

[0086] The diameter of the bionic tree leaves 23 is 20 - 40 cm, the diameter of the bionic tree rootstock 25 is 3 - 8 cm, and the height of the bionic tree rootstock 25 is 20 - 40 cm; the hard shell 31 of the bionic xylem of the bionic tree leaves, the hard shell 33 of the bionic phloem of the bionic tree leaves, the hard shell 30 of the bionic xylem of the bionic tree rootstock, and the hard shell 32 of the bionic phloem of the bionic tree rootstock are all made of plastic, separated into bionic xylem space and bionic phloem space, and filled with bionic xylem and bionic phloem materials respectively; the bionic xylem and bionic phloem materials can be the same or different, such as filter paper, gauze, etc., with capillary pores and can have capillary action. At the upper opening of the bionic phloem 26 of the bionic tree leaves, a graduated float 34 indicating the water level is inserted. The graduated float 34 indicating the water level is made of foam plastic, spherical with a diameter of 1 cm. The upper end of the graduated float 34 indicating the water level is connected to a wooden rod with a diameter of 0.5 cm, and there are scales on the wooden rod, which can show the upper edge condition of the water level in the bionic phloem 26 of the bionic tree leaves. On one side of the hard shell 30 of the bionic xylem of the bionic tree rootstock, an inlet is provided every 5 - 10 cm to enable the soil solution to enter the bionic xylem 29 of the bionic tree rootstock; the bionic xylem 27 of the bionic tree leaves and the hard shell 31 of the bionic xylem of the bionic tree leaves are open upward to the air for transpiration, and at the same time, parts where water can be added from the outside are provided on the bionic phloem 26 of the bionic tree leaves and the hard shell 33 of the bionic phloem of the bionic tree leaves.

[0087] Between the bionic xylem 27 and the bionic phloem 26 of the bionic tree leaf, a series of connecting parts 35 between the bionic xylem and the bionic phloem of the bionic tree leaf are arranged vertically at intervals of 5-10 cm; between the bionic xylem 29 of the bionic tree rootstock and the bionic phloem 26 of the bionic tree leaf, a series of connecting parts 36 between the bionic xylem and the bionic phloem of the bionic tree rootstock are arranged horizontally at intervals of 5-10 cm.

[0088] The connecting part 35 between the bionic xylem and the bionic phloem of the bionic tree leaf, and the connecting part 36 between the bionic xylem and the bionic phloem of the bionic tree rootstock are both tubular connections with a length of 0.5 cm and a diameter of 0.5 cm. As Figure 7 shown, a one-way valve 38 is provided in the tubular connection. The one-way valve 38 is fixed and controlled by a hinge 39, so that the opening angle of the one-way valve 38 is less than 30°. The one-way valve 38 opens when the bionic xylem 29 of the bionic tree rootstock cannot effectively obtain water from the soil and the water pressure is too high. At this time, water flows from the bionic phloem to the bionic xylem to supplement water and prevent the formation of bionic xylem embolism.

[0089] The bionic tree leaf 23 undergoes bionic transpiration under light conditions, and the water loss pulls the soil solution 37 into the bionic xylem 29 of the bionic tree rootstock and is transported upward from the bionic tree rootstock 25 along the bionic xylem 29 of the bionic tree rootstock to the bionic tree leaf 23. The bionic phloem always remains filled with water and is connected to the bionic xylem, thus avoiding the embolism phenomenon that may occur due to excessive water loss in the bionic xylem during bionic transpiration. The soil solution containing pollutants such as rare earths and ammonium nitrogen is continuously migrated out of the polluted soil under bionic transpiration, enters the bionic tree rootstock and then reaches the bionic tree leaf part.

[0090] Specifically, the bionic xylem 29 of the bionic tree rootstock is directly connected to the bionic xylem 27 of the bionic tree leaf. The bionic xylem 27 of the bionic tree leaf undergoes bionic transpiration under light conditions, resulting in water loss. The capillary force pulls the water in the bionic xylem 29 of the bionic tree rootstock into the bionic xylem 27 of the bionic tree leaf, and at the same time pulls the soil solution 37 into the bionic xylem 29 of the bionic tree rootstock. The bionic phloem 26 of the bionic tree leaf always remains filled with water. Since the bionic phloem 28 of the bionic tree rootstock is directly connected to the bionic phloem 26 of the bionic tree leaf, the water injected into the bionic phloem 26 of the bionic tree leaf can enter the bionic phloem 28 of the bionic tree rootstock due to gravity. Through the connecting part 35 of the bionic xylem and bionic phloem of the bionic tree leaf, controlled by the one-way valve 38, when the bionic xylem 27 of the bionic tree leaf loses water excessively, the water retained in the bionic phloem 26 of the bionic tree leaf flows unidirectionally from the bionic phloem 26 of the bionic tree leaf to the bionic xylem 27 of the bionic tree leaf, thus avoiding the embolism phenomenon that may occur due to excessive water loss in the bionic xylem 27 of the bionic tree leaf during bionic transpiration; the connecting part 36 of the bionic xylem and bionic phloem of the bionic tree rootstock, controlled by the one-way valve 38, when the bionic xylem 29 of the bionic tree rootstock loses water excessively, the water that enters the bionic phloem 28 of the bionic tree rootstock due to gravity flows unidirectionally into the bionic xylem 29 of the bionic tree rootstock, thus avoiding the embolism phenomenon that may occur due to excessive water loss in the bionic xylem 29 of the bionic tree rootstock during bionic transpiration.

[0091] The bionic tree rootstock 25 is buried in the soil when the soil is backfilled into the inter-ridge soil pit 19, and then flooded and covered with a film to form a strong reduction system. As Figure 8 、 Figure 9 shown, after the bionic tree rootstock 25 and the bionic tree leaf 23 are arranged in the strong reduction system, a simple greenhouse 40 and a greenhouse film 41 are established thereon. After the bionic tree rootstock 25 is buried, its upper end passes through the planting hole 42 on the upper film 16. The aperture of the planting hole 42 is 5 - 10 cm, and the center distance of the holes is 30 - 50 cm, which are arranged on the upper film 16 at equal distances. After the upper end of the bionic tree rootstock 25 passes through the upper film 16, the gap between the planting hole 42 and the bionic tree rootstock 25 is adhered with sealing tape 43 to prevent gas from escaping from under the film.

[0092] The combined application of the strong reduction treatment and the bionic transpiration technology and the valuable substance recovery system includes: a simple greenhouse 40 and a greenhouse film 41 equipped with a fresh air exchange window are erected above the soil treated by the strong reduction and the bionic tree. As Figure 10As shown in the figure, the fresh air exchange window includes a ventilation system 44, an exhaust system 45, an intake system 46, condensate 47, and a sensible heat exchange system 48. The sensible heat exchange system 48 heats the gas entering the simple greenhouse 40 and recovers the condensate 47 in the gas discharged from the simple greenhouse 40 to the elevated water tank 49. The water in the elevated water tank 49 is regularly made into an EDTA solution 50 with a concentration of 10 - 30 mM to wash the rare earth and ammonium nitrogen in the bionic tree leaves 23. After passing through the water pipe 51, it is recovered through the concentrated solution recovery system 52.

[0093] After the treatment of the polluted soil dug out from the soil pits between the slopes of the water landscape in the rare earth mining area is completed, the above-mentioned recoverable barrier system is maintained; the simple greenhouse 40, the upper covering film 16, and the lower soil anti-seepage film 17 are removed. The treated soil in the original soil pit between the slopes is piled up from the upper and lower edges of the original horizontal height of the soil pit between the slopes to the midline of the horizontal height to form a new soil ridge; the untreated soil of the original soil ridge of the water landscape slope in the rare earth mining area is dug out to form a new soil pit between the slopes; in the new soil pit between the slopes, the above-mentioned strong reduction and bionic transpiration scheme is also used to treat the soil.

[0094] Example 2

[0095] As Figures 1 - 10 , based on the treatment system for the polluted soil on the water landscape slope in the weathered crust eluvial rare earth mining area that combines strong reduction treatment and bionic transpiration technology in Example 1, a treatment method for the polluted soil on the water landscape slope in the weathered crust eluvial rare earth mining area that combines strong reduction treatment and bionic transpiration technology is provided, including the following steps:

[0096] S1. Construct a recoverable barrier system for pollutants in the surface rainfall runoff of the soil on the water landscape slope in the weathered crust eluvial rare earth mining area.

[0097] (1) Dig a soil pit without ridges with a certain depth in the left - right direction at a set horizontal height as the boundary between the polluted slope of the upstream surface rainfall runoff and the downstream slope to be treated; the soil pit without ridges is dug in the left - right direction along the contour line, with a rectangular cross - section, a depth of 0.75 - 1.5 m, and a width of 2.1 - 2.9 m.

[0098] (2)On one side where the ridge - less soil pit is connected to the upstream slope of the slope rainfall runoff, several layers of adsorption bags 10 filled with anion - exchange resin and adsorption bags 11 filled with cation - exchange resin are orderly stacked in the ridge - less soil pit. The stacking width of the adsorption bags 10 filled with anion - exchange resin and the adsorption bags 11 filled with cation - exchange resin is 1.6 - 2.4 m. The top plane of the tail of the adsorption bag stack is 0.25 - 0.5 m higher than the top plane of the head of the adsorption bag stack to control the flow velocity of the up - and - down water flow. The head of the stack of adsorption bags 10 filled with anion - exchange resin is connected to the polluted slope on the upstream side of the slope rainfall runoff. There is a gap with a width of about 0.5 - 0.8 m between the tail of the stack of adsorption bags 11 filled with cation - exchange resin in the ridge - less soil pit and the downstream slope to be treated. A certain amount of montmorillonite or uncontaminated borrowed soil is filled to form a left - and - right drainage soil ditch 12 with a depth of about 0.2 - 0.4 m, which is connected as a whole with one side of the downstream slope to be treated.

[0099] Part of the adsorption bags are adsorption bags 10 filled with anion - exchange resin, which can block sulfate, nitrate, etc. in the slope rainfall runoff; the other part are adsorption bags 11 filled with cation - exchange resin, which can block cations such as rare earths, heavy metals, and ammonium in the slope rainfall runoff. The adsorption bags are stacked in sequence. When the slope rainfall runoff (i.e., the runoff 9 flowing from the top of the mine mountain downward) flows through the adsorption bags, it first contacts only the adsorption bags 10 filled with anion - exchange resin for anion exchange; after the slope rainfall runoff flows through the adsorption bags filled with anion - exchange resin, it then contacts the adsorption bags 11 filled with cation - exchange resin for cation exchange.

[0100] (3)In the recoverable barrier system for pollutants in the slope rainfall runoff, the ionic pollutants in the slope rainfall runoff penetrate into the adsorption bags and are adsorbed on the anion or cation exchange resin in the adsorption bags through the processes of anion - exchange adsorption and cation adsorption. Subsequently, rare earths, nitrogen, and sulfur are desorbed and recovered, and the ion - exchange resin is regenerated. The particulate pollutants in the slope rainfall runoff are deposited in the left - and - right water ditches left horizontally parallel to the slope at the middle part of the upper part of the adsorption bag stack. After the sediments are collected and stored in sufficient quantity, they are placed in the treatment system that combines strong reduction treatment and bionic transpiration technology of the present invention and are treated according to the method of the present invention.

[0101] S2. Construct a strong reduction treatment system for the polluted soil of the water - based landscape slope in the weathered crust elution - deposition type rare earth mine area, transform the water - based landscape slope of the rare earth mine area to be treated into gentle - slope terraced fields, and perform strong reduction treatment on the soil.

[0102] (4)At the soil of the water landscape slope to be treated that interfaces with the drainage soil ditch 12 at the lower edge of the pollutant recoverable barrier belt, dig and form an earth ridge 18 at the same horizontal height; then, at several set horizontal heights along the slope direction of the water landscape slope, dig a drainage soil ditch 12 with a width of about 0.5 m and a depth of 0.2 - 0.4 m in the left - right direction, and form earth ridges 18 on both sides of the drainage soil ditch 12; between the earth ridge 18 at the lower edge of the drainage soil ditch 12 at each horizontal height and the earth ridge 18 at the upper edge of the drainage soil ditch 12 at the next horizontal height, dig an inter - ridge soil pit 19 with a certain depth. Lay a bottom - laid soil anti - seepage membrane 17 in the inter - ridge soil pit 19 between the two earth ridges 18 after excavation, then supplement and backfill contaminated soil 20 into the bottom - laid soil anti - seepage membrane 17, and level the land.

[0103] The depth of the inter - ridge soil pit 19 is 0.75 - 1.5 m, the width is 1.3 - 2.6 m, the height of the earth ridge 18 is 0.4 - 0.6 m, and the width is 0.3 - 0.4 m. After the construction of the soil strong reduction system, carry out the strong reduction treatment for 2 - 4 weeks, effectively reduce the pollution levels of sulfates and nitrates in the water landscape contaminated soil in the weathered crust elution - deposition rare earth ore area, effectively reduce the toxicity of hexavalent chromium in the soil; effectively passivate the heavy metals in the contaminated soil, reducing their bioavailability; convert tetravalent cerium in the soil into trivalent cerium that is easy to migrate. Effectively reduce the soil acidity, the concentration of soil aluminum ions, and improve the physical and chemical properties of the soil.

[0104] (5)Add an appropriate amount of easily degradable organic materials to the leveled contaminated soil and mix them evenly, then carry out the flooding treatment 22 to form a soil - water interface 21, and finally cover with an upper - laid membrane 16 for soil strong reduction treatment to form a soil strong reduction treatment system.

[0105] S3. Construct a bionic transpiration system, and implant bionic trees that can carry out bionic transpiration in the contaminated soil treated by the above - mentioned strong reduction treatment.

[0106] (6) Assemble the bionic xylem 29 and the bionic xylem hard shell 30 of the bionic tree root and stem, the bionic phloem 28 and the bionic phloem hard shell 32 of the bionic tree root and stem into the bionic tree root and stem 25; assemble the bionic xylem 27 and the bionic xylem hard shell 31 of the bionic tree leaf, the bionic phloem 26 and the bionic phloem hard shell 33 of the bionic tree leaf into the bionic tree leaf 23. A pore channel is provided in the center of the bionic phloem 26 of the bionic tree leaf. The bionic xylem 29 of the bionic tree root and stem passes through the bionic phloem 26 of the bionic tree leaf through this pore channel and is directly connected to the bionic xylem 27 of the bionic tree leaf. A connecting part is provided between the bionic phloem and the bionic xylem. A connecting part 36 between the bionic xylem and the bionic phloem of the bionic tree root and stem is arranged in the horizontal direction of the bionic tree root and stem 25, and a connecting part 35 between the bionic xylem and the bionic phloem of the bionic tree leaf is arranged in the vertical direction of the bionic tree leaf 23 to keep it connected; one-way valves 38 controlled by hinge hinges 39 are provided at both connecting parts, which can be replenished with water by the bionic phloem when the bionic xylem is short of water to avoid embolism of the bionic xylem. A graduated float 34 indicating the water level is inserted into the upper opening of the bionic phloem 26 of the bionic tree leaf, which can show the upper edge condition of the water level in the bionic phloem.

[0107] (7) When the backfilled polluted soil 20 is backfilled onto the underlying soil anti-seepage membrane 17 in the soil pit 19 between the ridges, bury the bionic tree root and stem 25 into the soil, mix the organic materials evenly, and then carry out flooding and film covering. The upper end of the bionic tree root and stem 25 passes through the planting hole 42 on the upper film 16; then use sealing tape 43 to paste the gap between the upper film 16 and the bionic tree root and stem 25 to prevent gas from escaping from under the upper film 16. Planting holes 42 for planting bionic trees are arranged at equal intervals on the upper film 16, with a hole diameter of 5 - 10 cm and a center distance of 30 - 50 cm between the small holes.

[0108] (8) Connect the bionic tree leaf to the bionic root and stem part of the bionic tree.

[0109] The bionic tree structure includes bionic tree leaves 23 and bionic tree roots 25. The bionic xylem 27 of the bionic tree leaves undergoes bionic transpiration and water loss under light conditions, pulling the aqueous solution in the bionic xylem 29 of the bionic tree roots up to the bionic tree leaves 23 for replenishment, thereby pulling the soil solution into the bionic xylem 29 of the bionic tree roots. The bionic phloem 26 of the bionic tree leaves and the bionic phloem 28 of the bionic tree roots are an integral whole, always kept filled with water, and are in communication with the bionic xylem 27 of the bionic tree leaves. The bionic phloem 28 of the bionic tree roots is also in communication with the bionic xylem 29 of the bionic tree roots; through the one-way valve 38, water can be replenished from the bionic phloem to the bionic xylem, thus avoiding embolism phenomena in the bionic xylem and bionic phloem during bionic transpiration. The soil solution containing pollutants such as rare earths and ammonium nitrogen is continuously migrated out of the polluted soil under the bionic transpiration of the bionic tree, enters the bionic xylem 29 of the bionic tree roots, and then reaches the bionic xylem 27 of the bionic tree leaves.

[0110] S4. Implement the combined application of strong reduction treatment and bionic transpiration technology and the recovery of valuable substances. Build a simple greenhouse equipped with a fresh air exchange window above the strongly reduced soil and the bionic tree, implement soil strong reduction and bionic transpiration, and recover rare earths and ammonium nitrogen from the bionic tree leaves.

[0111] (9)There is a simple greenhouse 40 with a fresh air exchange window above the strongly reduced soil and the bionic tree. The fresh air exchange window consists of a ventilation system 44, an exhaust system 45, and an intake system 46; the fresh air exchange window heats the gas entering the simple greenhouse 40 through a sensible heat exchange system 48 and recovers the condensed water 47 in the exhaust gas outside the greenhouse to the high-level water tank 49.

[0112] (10)Regularly make the water in the high-level water tank 49 into an EDTA solution 50 with a certain concentration to leach rare earths and ammonium nitrogen in the bionic tree leaves 23 and recover them.

[0113] (11)After the treatment of the backfill polluted soil 20 dug out from the soil pit 19 between the slopes of the water landscape in the rare earth mining area is completed, maintain the above recoverable barrier system; remove the simple greenhouse 40, the upper covering film 16, and the lower laying soil anti-seepage membrane 17, and stack the treated backfill polluted soil 20 in the original soil pit 19 from the upper and lower edges of the original horizontal height of the soil pit to the midline of the horizontal height to form a new soil ridge; dig out the soil in the original soil ridge 18 of the water landscape slope in the rare earth mining area that has not been treated to form a new soil pit between the ridges; in the new soil pit between the ridges, also use the above-mentioned strong reduction and bionic transpiration scheme to treat the soil.

[0114] After 6 months of treatment with the treatment method of the present invention, the physicochemical properties of the polluted soil on the water landscape slope in the weathered crust eluvial rare earth mining area changed as follows: the soil pH value increased from 4.54 - 5.09 to 5.51 - 6.86, and the organic matter content increased from 0.32 - 0.44% to 1.66 - 1.91%. The ammonium nitrogen in the soil decreased from 51.3 - 167.4 mg / kg to 10.6 - 25.2 mg / kg, the nitrate nitrogen decreased from 20.1 - 40.4 mg / kg to <10 mg / kg, and the sulfate radical decreased from 20.2 - 105.8 mg / kg to 9.5 - 14.3 mg / kg. The rare earth element content decreased from 699.6 - 942.4 mg / kg to 298.4 - 439.1 mg / kg. The bioavailable heavy metal content was determined by extraction using the soil environmental quality standard method: hydrochloric acid was used to adjust pure water to pH 5.8 - 6.3 as the extraction agent, and the soil sample (g) and the extraction agent (mL) were mixed at a solid-liquid ratio of 1:10, and the volume of the mixed solution was made more than 500 mL; the sample bottle was placed on an oscillator at room temperature of 20°C and normal pressure of 101.325 kPa, and oscillated continuously at 200 times / min with an amplitude of 4 - 5 cm for 6 hours to leach out the pollutants. The Pb content in the soil leachate decreased from 1.06 - 6.13 mg / L to <0.01 mg / L, the Cd content decreased from 0.02 - 0.09 mg / L to <0.01 mg / L, and the As content decreased from 0.44 - 1.21 mg / L to <0.01 mg / L; the hexavalent chromium content in the soil (determined by the diphenylcarbazide method) decreased from 141.8 - 1027.2 mg / kg to <0.5 mg / kg, and the heavy metal dissolution amount of the treated soil was low; the above shows that soil pollutants will not cause secondary pollution to water bodies. At the same time, the recovery rate of rare earth elements in the soil was 83.3 - 87.6%, and the recovery rate of ammonium nitrogen was greater than 53.2 - 66.5%.

Claims

1. A method for treating soil contaminated by weathering crust leaching rare earth mining areas on water landscape slopes, characterized in that: The treatment method specifically comprises the following steps: S1. Construct a recyclable barrier system for pollutants in slope rainfall runoff to block pollutants that are transferred into the runoff in water-soluble or particle form due to scouring of slope polluted soil; S2. Construct a strong reduction treatment system for contaminated soil, transform the water landscape slope in the rare earth mining area to be treated into gentle slope terraces, and carry out strong reduction treatment on the contaminated soil; S3. Constructing a bionic transpiration system, implanting a bionic tree for bionic transpiration in the contaminated soil treated with strong reduction in step S2; S4. A greenhouse is set up above the strongly reduced contaminated soil and the bionic tree to implement the combined application of soil strong reduction and bionic transpiration and recovery of valuable substances, and to recover rare earth and ammonium nitrogen from the bionic tree leaves; In the bionic tree, the bionic xylem of the bionic tree rhizome is directly connected with the bionic xylem of the bionic tree leaf. During transpiration, the capillary force pulls the soil solution into the bionic xylem of the bionic tree rhizome and then into the bionic xylem of the bionic tree leaf. The bionic phloem of the bionic tree rhizome is directly connected with the bionic phloem of the bionic tree leaf. The water injected into the bionic phloem of the bionic tree leaf enters the bionic phloem of the bionic tree rhizome due to gravity. At the same time, the connection between the bionic xylem of the bionic tree leaf and the bionic phloem and the connection between the bionic xylem of the bionic tree rhizome and the bionic phloem are all capillary. A one-way valve is arranged in the tubular connection. When the bionic xylem of the bionic tree leaf loses excessive water, the water injected into the bionic phloem of the bionic tree leaf flows unidirectionally to the bionic xylem of the bionic tree leaf through the one-way valve, thereby avoiding the embolism caused by the excessive water loss of the bionic xylem of the bionic tree leaf during the bionic transpiration. When the bionic xylem of the bionic tree root and stem loses excessive water, the water in the bionic phloem of the bionic tree root and stem flows unidirectionally to the bionic xylem of the bionic tree root and stem through the one-way valve, thereby avoiding the embolism caused by the excessive water loss of the bionic xylem of the bionic tree root and stem during the bionic transpiration.

2. The method for treating soil contaminated by weathering crust leaching type rare earth mining area water landscape slope according to claim 1, characterized in that: The method for constructing a recyclable barrier system for pollutants in slope rainfall runoff in step S1 is: (1) digging a non-ridged soil pit in the left and right directions at the upper edge of the horizontal height of the water landscape slope of the weathered crust eluvial rare earth mining area to be treated, as a boundary between the upstream polluted slope of the slope rainfall runoff and the downstream slope to be treated; the non-ridged soil pit is dug in the left and right directions along the contour line; (2) The adsorption bags are piled on one side of the soil pit without ridges connected to the polluted slope upstream of the slope runoff. The middle part of the upper part of the adsorption bag pile leaves a left-right ditch parallel to the slope in the horizontal direction. The top plane of the tail of the adsorption bag pile is higher than the top plane of the head of the adsorption bag pile. The head of the adsorption bag pile is connected to the polluted slope upstream of the slope runoff. (3) There is a gap between the tail of the adsorption bag stack in the pit without ridge and the downstream slope to be treated. Montmorillonite or uncontaminated guest soil is filled in to form a recoverable barrier system for pollutants in the slope rainfall runoff. The lower edge of the drainage ditch is connected to the downstream slope to be treated.

3. The method for treating soil contaminated by weathering crust leaching type rare earth mining area water landscape slope according to claim 2 is characterized in that: The adsorption bags in step (2) are adsorption bags filled with anion exchange resin and adsorption bags filled with cation exchange resin. The adsorption bags are stacked in sequence so that the slope rainfall runoff flows through the adsorption bags and first contacts only the adsorption bags filled with anion exchange resin and then contacts the adsorption bags filled with cation exchange resin.

4. The method for treating soil contaminated by weathering crust leaching type rare earth mining area water landscape slope according to claim 2, characterized in that: The method for constructing a strong reduction treatment system for contaminated soil in step S2 is: (4) At the lower edge of the left-right drainage ditch at the lower edge of the recoverable barrier system for pollutants in the slope rainfall runoff, dig and build ridges at the contaminated soil on the slope of the downstream slope to be treated that borders the drainage ditch; then, dig a number of left-right drainage ditches along the slope of the downstream slope to be treated, fill the drainage ditches with montmorillonite or uncontaminated guest soil, and then build ridges at the contaminated soil on the slope of the downstream slope to be treated that borders both sides of the drainage ditch; dig inter-ridge pits between the lower edge ridge of each drainage ditch and the upper edge ridge of the next drainage ditch, and lay an underlay soil impermeable membrane on top of each inter-ridge pit and the unit formed by the ridges on both sides, and then backfill the contaminated soil in the excavated inter-ridge pits onto the underlay soil impermeable membrane above the inter-ridge pits, and level the land; (5) Add easily degradable organic materials to the leveled backfill contaminated soil and mix well, flood it with water, and lay a covering film on top of the unit formed by the earth pit between each ridge and the earth ridges on both sides to construct a strong reduction treatment system for the backfill contaminated soil, and then carry out strong reduction treatment.

5. The method for treating soil contaminated by weathering crust leaching type rare earth mining area water landscape slope according to claim 4 is characterized in that: The drainage ditch in step (4) is 0.4-0.6m wide and 0.2-0.4m deep; the pit between ridges is 0.75-1.5m deep and 1.3-2.6m wide; The height of the earth ridge is 0.4-0.6m, and the width is 0.3-0.4m. The cycle of the strong reduction treatment in step (5) is 2-4 weeks. Small holes for planting bionic trees are arranged at equal distances on the upper film of the earth ridge and the earth pit between the ridges, with a hole diameter of 5-10cm and a center spacing of 30-50cm.

6. The method for treating soil contaminated by weathering crust leaching type rare earth mining area water landscape slope according to claim 4, characterized in that: The method of implanting a bionic tree for performing bionic transpiration in step S3 comprises the following steps: (6) Assemble the bionic xylem and its hard shell of the bionic tree rhizome, and the bionic phloem and its hard shell of the bionic tree rhizome into a bionic tree rhizome; assemble the bionic xylem and its hard shell of the bionic tree leaf, and the bionic phloem and its hard shell of the bionic tree leaf into a bionic leaf; set a horizontal connection part on the bionic tree rhizome, and set a vertical connection part on the bionic tree leaf to keep them connected; set a one-way valve controlled by a hinge at the connection part, and when each bionic xylem is short of water, the bionic phloem will replenish water to avoid embolism of the bionic xylem; insert a scaled float indicating the water level into the upper opening of the bionic phloem of the bionic leaf to display the water level of the upper edge of the bionic phloem; (7) When the contaminated soil is backfilled onto the bottom soil impermeable membrane of the pit between ridges in step (4) of constructing the strong reduction treatment system for contaminated soil, the assembled bionic tree rhizomes are buried in the soil, and then flooded and covered with an upper membrane, and the upper end of the bionic tree rhizomes passes through the planting holes set on the upper membrane; then the gap between the upper membrane and the bionic tree rhizomes is closed to prevent gas from escaping; (8) Connect the assembled bionic leaf blades to the assembled bionic tree roots.

7. The method for treating soil contaminated by weathering crust leaching type rare earth mining area water landscape slope according to claim 6, characterized in that: The bionic xylem of the bionic tree leaf is arranged above the space surrounded by the edge of the bionic phloem of the bionic tree leaf; a hole is arranged in the center of the bionic phloem of the bionic tree leaf, and the bionic xylem of the bionic tree rhizome passes through the bionic phloem of the bionic tree leaf through the hole and is directly connected with the bionic xylem of the bionic tree leaf; the diameter of the bionic tree leaf is 20-40cm, the diameter of the bionic tree rhizome is 3-8cm, and the height of the bionic tree rhizome is 20-40cm; the hard shells of the bionic tree leaf and the bionic tree rhizome are both made of plastic, and are divided into a bionic xylem space and a bionic phloem space; On the outer shell of one side of the bionic xylem of the bionic tree rhizome, a water inlet is arranged every 5-10 cm to allow the soil solution to enter the bionic xylem of the bionic tree rhizome; the bionic xylem of the bionic tree leaf is opened upward to the air to perform transpiration; A series of connection parts are arranged between the bionic xylem and the bionic phloem of the bionic tree leaf at intervals of 5-10 cm along the vertical direction; a series of connection parts are arranged between the bionic xylem and the bionic phloem of the bionic tree root at intervals of 5-10 cm along the horizontal direction; The connecting parts of the bionic xylem and the bionic phloem of the bionic tree leaf, as well as the connecting parts of the bionic xylem and the bionic phloem of the bionic tree rhizome, are all tubular connections with a length of 0.5-1 cm and a diameter of 0.5-1 cm. A one-way valve is provided in the tubular connection, and the one-way valve is fixed and controlled by a hinge. The one-way valve opens when the bionic xylem cannot effectively obtain water from the soil and the water pressure is too high. At this time, water flows from the bionic phloem to the bionic xylem to replenish water and prevent the formation of bionic xylem embolism.

8. The method for treating soil contaminated by weathering crust leaching type rare earth mining area water landscape slope according to claim 1, characterized in that: In step S4, the greenhouse is a simple greenhouse with fresh air exchange windows; the method of implementing the combined application of soil strong reduction and bionic transpiration and valuable material recovery, and recovering rare earth and ammonium nitrogen from bionic tree leaves, comprises the following steps: (9) A simple greenhouse with fresh air exchange windows is built above the strongly reduced contaminated soil and bionic trees. The fresh air exchange windows heat the gas entering the simple greenhouse through a sensible heat exchange system and recover the condensed water in the exhaust gas of the simple greenhouse to a high-level water tank; (10) Rare earth ions and ammonium nitrogen in the soil solution enter the bionic tree leaves from the roots and stems, and are concentrated as the water evaporates; the rare earth ions and ammonium nitrogen in the bionic tree leaves are eluted with EDTA solution in a high-level water tank and recovered; (11) After the treatment of the contaminated soil excavated from the pits between ridges in the water landscape slope of the weathering crust leaching type rare earth mining area is completed, the recyclable barrier system shall be maintained; the simple greenhouse shall be removed, the upper film shall be covered, and the anti-seepage film shall be laid below, and the treated soil in the original pits between ridges shall be piled from the upper and lower edges of the horizontal height of the original pits between ridges to the midline of the horizontal height to form a new ridge; The untreated soil of the original earth ridges of the water landscape slope in the rare earth mining area is dug out to form new pits between ridges; in the new pits between ridges, the same strong reduction and bionic transpiration methods are continued to be used to treat the soil.

9. The method for treating soil contaminated by weathering crust leaching type rare earth mining area water landscape slope according to claim 1, characterized in that: The water landscape slope in the weathering crust elution type rare earth mining area is a water landscape slope with a slope of less than 25°, and the gentle slope terrace is a gentle slope terrace with a slope of less than 10°.

10. An application of the method for treating soil contaminated by weathering crust elution type rare earth mining area water landscape slope land according to claim 1 in treating and regenerating soil contaminated by weathering crust elution type rare earth mining area water landscape slope land.

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