Method for repairing lead-zinc tailings pond by using indocalamus

Abstract

The invention discloses a method for repairing a lead-zinc tailing pond by utilizing indocalamus, and belongs to the technical field of soil remediation. The method comprises the following steps: establishing a green recovery unit, improving soil, selecting an indocalamus planting material which is resistant to heavy metals and high in adaptability, and using a customized planting module, a special topdressing mode and a microbial agent; and resources obtained after cutting in winter are recycled, and rapid regreening and stable plant covering of the tailings pond are achieved. Compared with the prior art, the method has the advantages of simplicity and convenience in operation, high flexibility, low cost, good landscape effect, sustainable cyclic utilization and the like, and is also suitable for large-scale ecological restoration projects.

Description

Technical Field

[0001] The invention relates to the technical field of soil restoration, and in particular to a method for restoring a lead-zinc tailings pond by utilizing indigo bamboo. Background Art

[0002] China is rich in lead and zinc mineral resources and the mineralization areas are concentrated. While making great contributions to the development of the national economy, its mining and smelting process also leads to pollution problems that cannot be ignored. Tailings areas, as the main storage point for mining waste, not only occupy a large amount of land resources, but also the heavy metals and other pollutants contained in the tailings are easy to penetrate into the soil, causing serious damage to the surrounding ecological environment. It is urgent to repair the polluted soil in the lead and zinc tailings area, which is of great significance to promoting the construction of national ecological civilization and promoting the harmonious coexistence of man and nature.

[0003] Traditional restoration technology is mainly based on the principle of physical restoration. This kind of restoration device requires a large amount of technical engineering, high cost, and will damage the soil structure, so it has low feasibility. Phytoremediation is favored because of its low cost and advantages such as soil and water conservation, environmental friendliness, and ease of operation. However, lead-zinc tailings ponds still have many limitations such as poor soil physical structure, extreme barrenness, poor water and fertilizer retention capacity, and heavy metal complex pollution. Most plants grow slowly and are difficult to survive for a long time; and due to the heterogeneity of the soil environment, plant growth is unevenly distributed in time and space. These problems ultimately lead to difficulties in stable and continuous vegetation restoration, high greening costs, and poor landscape effects.

[0004] In lead and zinc contaminated soils, Poaceae plants show strong tolerance. Among them, perennial bamboo plants are widely distributed, grow rapidly and can adapt to adverse stress through clonal integration. Their huge underground whip root system is mainly distributed in the shallow soil layer, which has good innate conditions for absorbing soil heavy metals.

[0005] Among them, plants of the genus Indocalamus have been reported to have good results in soil remediation, especially in soil remediation of heavy metal pollution. However, although Indocalamus has strong tolerance and accumulation capacity for heavy metals, its growth is still restricted by the environment due to the low bulk density, poor nutritional conditions, and a large amount of rock fragments in the soil of the lead-zinc tailings pond. Therefore, when it is used for the remediation of the lead-zinc tailings pond, its remediation effect needs to be further improved. Summary of the invention

[0006] The purpose of the present invention is to provide a method for repairing a lead-zinc tailings pond using indigofera truncatula to solve the above-mentioned problem.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows: a method for repairing a lead-zinc tailings pond using indigo bamboo comprises the following steps: (1) Establishment of reforestation unit: Establish a reforestation unit in the selected area of ​​the tailings pond and divide it into at least three sub-units; (2) Soil improvement in the first year: Cover the contaminated soil surface of the entire regreening unit with soil, apply biological organic fertilizer and water-retaining agent to the sub-unit located in the middle, and use a rotary tiller to plow the soil of the entire regreening unit; (3) Indocalamus chinensis planting: Select Indocalamus chinensis planting materials, transplant them into planting modules, and then apply compound fertilizer as topdressing in each module and apply microbial agents; (4) Winter mowing: mowing the old bamboos above ground in the central module. (5) soil improvement and expansion of regreening areas within the unit in the second year; (6) After that, the unit will be initially regreened and normal agronomic management will be carried out, which will form a good landscape effect after 1 to 2 years. The planting modules in the unit can be removed and reused after the regreening is completed.

[0008] As a preferred technical solution, in step (1), the size of each regreening unit is 7.2×7.2~10.8×10.8m, and the sub-units are nine of the same size, each of which is 2.4×2.4~3.6×3.6m in size.

[0009] This is a module matching design. For example, if the unit side length is 7.2m, the corresponding module side length is 0.8m; if the unit side length is 10.8m, the corresponding module side length is 1.2; the inventor has proved through a large number of experiments that if the module side length is too small, it is not easy for a single clump of Indocalamus to develop, and if it is too large, it is impossible to ensure the spread of the whip out of the module; the optimal unit size is 9×9m, and the optimal sub-unit size is 3×3m, that is, the module side length is 1m.

[0010] As a preferred technical solution, in step (2), the specific components and dosage of the bio-organic fertilizer are: nitrogen: phosphorus: potassium = 3:1:2~4:1:2, the organic matter content is 25~40%, the dosage is 60~90g / m², and the application amount per unit is 4.86~7.29kg; the water retaining agent is a highly absorbent resin SAPs, the dosage is 1~2kg / m², and the application amount per unit is 81~162kg.

[0011] As a preferred technical solution, in step (3), the compound fertilizer is applied once in mid-March, June, September and December, for a total of four times, wherein compound fertilizer is applied along the edges of the central module within 20 cm from the center in March and June, and compound fertilizer is applied evenly to the other modules normally; in September and December, compound fertilizer is evenly applied to the modules except the central module, wherein the composition of the compound fertilizer is nitrogen: phosphorus: potassium = 3:1:2~4:1:2, the organic matter content is 25~40%, and the dosage is 60~75g / m²; the microbial agent is selected from Bacillus subtilis (Bacillus subtilis )、Bacillus megaterium( Bacillus megaterium ), Thiobacillus thiooxidans ( Thiobacillus thiooxidans ) with a content of 1×10 8 ~1×10 9 CFU / mL, the culture method is to put the inoculated culture medium into a shake bottle, place it on a shaker, shake it at a speed of 150-200rpm, maintain a good oxygen supply, and use it after the bacteria in the culture solution reaches the logarithmic growth period. The method of use is to evenly spray it on the soil surface around the central module bamboo, the amount is 100~500mL, the application time is mid-March, May, and July, and the microbial agent is applied 3 times in total.

[0012] As a preferred technical solution, the microorganism is Thiobacillus thiooxidans.

[0013] As a preferred technical solution, the indocalamus is indocalamus sibiricum ( Indocalamus decorus ).

[0014] Indocalamus IndocalamusNakai ) is a type of low shrub-like bamboo plant. Compared with tree-like bamboo plants, it has a stronger ability to adapt to the harsh soil environment in mining areas, and its above-ground enriched parts are easier to harvest and recycle. It is a potential plant for regreening of soil pollution in lead-zinc tailings ponds. In the previous comparative experiments, the inventors finally found through a large number of screening tests that plants of the genus Indocalamus (taking Indocalamus sibiricus as an example) have stronger lead accumulation and tolerance capabilities than most plants of the genus Phyllostachys (Philadelphus sibiricus and Phyllostachys sibiricus) and Phyllostachys sibiricus (Philadelphus sibiricus). After being planted in 300 mg / kg lead-contaminated soil for 8 months, the lead accumulation of Indocalamus sibiricus was 11.43%, 121.43%, and 83.54% higher than that of Phyllostachys sibiricus, Phyllostachys sibiricus, and Phyllostachys sibiricus, respectively; after 15 After being planted in soil contaminated with 100mg / kg lead for 8 months, the lead accumulation of Indocalamus fulva was 12.09%, 94.67% and 150.35% higher than that of Phyllostachys sibiricum, Phyllostachys philadelphus and Phyllostachys angustifolia, respectively; in addition, after being planted in soil contaminated with 1500mg / kg lead for 8 months, the biomass of Indocalamus fulva was 53.19%, 150.76% and 59.51% higher than that of Phyllostachys sibiricum, Phyllostachys philadelphus and Phyllostachys angustifolia, respectively, making it more suitable for regreening projects.

[0015] As a preferred technical solution, in step (3), the specification of the planting module is 0.8×0.8×0.4~1.2×1.2×0.4m, iron rings are set at the four corners of the top surface for easy installation and use, holes are opened around to allow the bamboo whips to spread and grow outward, and the open cutting groove on the top is used to break the whips; that is, the preferred planting module depth is 0.4m, which is aligned with the tillage depth.

[0016] As a preferred technical solution, in step (3), the length of the transplanted indigo bamboo in the planting module is 1-1.5 m, and the number of standing plants is 40-80.

[0017] As a preferred technical solution, in step (4), the cut bamboo leaves and bamboo stalks are collected and crushed.

[0018] Furthermore, the crushed bamboo leaves can be composted and fermented to produce bamboo leaf fertilizer, and the bamboo stalks can be prepared into biochar and used for soil improvement in the second year.

[0019] As a preferred technical solution, in step (5), the specific method for improving the soil and expanding the greening area within the unit is as follows: covering the surface of the contaminated soil in the subunits other than the middle subunit with soil, applying bamboo leaf fertilizer, bamboo stalk biochar, biological organic fertilizer, and water retaining agent, and tilling the soil with a rotary tiller to a depth of 40 cm, digging a 0.4 m deep planting pit at the center of each subunit except the middle subunit at 1×1 m, cutting the module in the middle subunit downward along the cutting groove of the module itself with a cutting tool to a depth of 0.4 m, filling it into the subunit and watering it thoroughly to fix it; applying compound fertilizer in each subunit for topdressing in March, June, September, and mid-December, and applying microbial agents in the central module of each subunit in mid-March, May, and July, the method is the same as the aforementioned step (3).

[0020] The present invention achieves rapid greening and stable plant coverage of the tailings pond by establishing a greening unit, improving the soil, selecting heavy metal-resistant and highly adaptable Indocalamus chinensis planting materials, coordinating with customized planting modules, special topdressing methods, the use of microbial agents, and recycling resources after winter mowing. The present invention has the advantages of simple operation, strong flexibility, low cost, good landscape effect, and sustainable recycling, and is also suitable for large-scale ecological restoration projects.

[0021] Compared with the prior art, the present invention has the following advantages: 1. The bamboo used in the present invention has a large biomass, strong tolerance, and is a perennial plant. Combined with the technology of the present invention, it can be planted once and then the restoration area can be expanded by in-situ division and seedling raising. Cultivation and restoration are carried out simultaneously, which is economical and efficient. Specifically, by using the method of the present invention, a clump of indigo bamboo can achieve a height of 51.84 to 116.64 m in 3 to 4 years. 2 The average lead concentration of indigo bamboo in the regreening area was 109.78~435.88mg / m 2 ; 2. The indocalamus used in the present invention generally has large and beautiful leaves and a compact plant shape. Under this technology, the planting module is used for regreening, which is easy to operate and flexible, and can form an orderly plant landscape in the entire regreening unit at the same time, with a good regreening effect; 3. The Thiobacillus thiooxidans used in the present invention is a tolerant microorganism selected after the actual planting of Indocalamus truncatum in the lead-zinc tailings area, which is more targeted and has a good ecological restoration effect; 4. The present invention uses the cut bamboo leaves to prepare fertilizers and the cut bamboo stalks to prepare biochar, which is used for soil improvement in the second year, thus realizing waste recycling; 5. The cutting tool provided by the present invention can quickly cut off the underground whip to separate the modules, saving time and effort. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the greening unit of Example 1; Figure 2 This is a schematic diagram of the planting module starting from the first year of step (3) of Example 1; Figure 3 This is a schematic diagram of the planting module at the end of the first year of step (3) of Example 1; Figure 4 A side view of the planting module in step (3) of Example 1; Figure 5 A front view of the planting module in step (3) of Example 1; Figure 6 A top view of the planting module in step (3) of Example 1; Figure 7 A schematic diagram of a regreening unit at the beginning of the second year of step (5) of Example 1; Figure 8 A schematic diagram of a regreening unit at the end of the second year of step (5) of Example 1; Fig. 9 This is a schematic diagram of the greening module after cutting in step (5) of Example 1; Fig.10 This is a schematic diagram of completing the greening process in step (6) of Example 1; Fig.11 A front view of the cutting tool used in Example 1; Fig.12 A top view of the cutting tool used in Example 1.

[0023] In the figure: 1. iron ring; 2. opening; 3. cutting groove; 4. handle; 5. connecting part; 6. blade. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings. Example 1

[0025] The experiment in this embodiment is located in the Fuquan lead-zinc mining area in Hanyuan County, Ya'an City, Sichuan Province, which belongs to the Tangjia-Wusi River lead-zinc mining belt. After years of mining, a large number of tailings ponds have been formed, causing serious damage to the surrounding ecological environment. The average lead content of the soil in the tailings pond of the test site is 1551.91±853.40mg / kg.

[0026] The repair method for the tailings pond includes the following steps: (1) Establish a 9×9m reforestation unit in the selected area of ​​the tailings pond, and further divide it into 9 sub-units, each with a size of 3×3m. Figure 1 As shown in the figure; clean the soil surface, remove large pieces of gravel and grass, level the land, and set up 6 greening units in total; (2) Cover the soil surface of the regreening unit with 10 cm of soil, apply biological organic fertilizer and water retaining agent to the central unit, and then use a rotary tiller to plow the soil of the entire regreening unit to a depth of 40 cm; The specific composition of the bio-organic fertilizer is N:P:K=4:1:2, the organic matter content is 40%, and the dosage is 90g / m 2 , the application amount per unit is 7.29kg; The water-retaining agent is a super absorbent resin (SAPs), and the dosage is 2kg / m 2 , the application amount per unit is 162kg; (3) Select two-year-old bamboo planting materials that grow quickly, have strong adaptability, and have the ability to absorb heavy metals, and transplant them into 1×1×0.5m planting modules in February. Figure 2 As shown in the figure, the length of the bamboo whip in the module is 1-1.5m, and the number of standing plants is 40-80. Then, a planting pit with a depth of 0.4m is dug in the central subunit, and the module planted with bamboo is placed in the center, and the subunit is filled with 8 empty modules, as shown in the figure. Figure 3 As shown, then backfill the soil and water thoroughly. After completion, carry out normal watering and weeding maintenance; apply compound fertilizer in each module for topdressing in March, June, September and mid-December, and apply microbial agents in the central module in mid-March, May and July; The side view, top view and front view of the planting module are as follows: Figure 4 , Figure 5 and Figure 6 As shown, iron rings 1 are arranged at the four corners of the top surface for easy installation and use, holes 2 are opened around the top surface so that the bamboo whip can spread and grow outward, and the cutting groove 3 on the top surface is used to cut the whip; The indocalamus is broadleaf indocalamus ( Indocalamus latifolius )、Hunan Indocalamus ( Indocalamus hunanensis )、Phyllostachys grandis( Indocalamus lacunosus )、Beautiful Indocalamus ( Indocalamus decorus )、Dwarf bamboo( Indocalamus pedalis )、Redwater bamboo( Indocalamus chishuiensis ), which are respectively set in 6 greening units; The topdressing method is to apply compound fertilizer in the range of 20 cm from the edge of the central module to the center in mid-March and June, and apply compound fertilizer evenly in other modules; the composition of compound fertilizer is nitrogen: phosphorus: potassium = 4:1:2, the organic matter content is 40%, and the dosage is 75g / m²; in mid-September and December, compound fertilizer is evenly applied in other modules except the central module; the composition of compound fertilizer is nitrogen: phosphorus: potassium = 4:1:2, the organic matter content is 40%, and the dosage is 75g / m²; The bacterial species of the microbial agent applied in the central module is Thiobacillus thiooxidans ( Thiobacillus Thiooxidans ), the application time was mid-March, May, and July, and the bacterial solution concentration was 1×10 8 CFU / mL, the method of use is to spray evenly on the soil surface around the central module of Indocalamus, the dosage is 100mL.

[0027] (4) In December, the above-ground old bamboos of the central module were cut, and the cut bamboo leaves and bamboo stalks were collected and crushed; the crushed bamboo leaves were composted and fermented to obtain bamboo leaf fertilizer, and the bamboo stalks were prepared as biochar; (5) In February of the following year, the contaminated soil surface of the subunits except the central subunit was covered with 10 cm of soil, bamboo leaf fertilizer, bamboo stalk biochar, biological organic fertilizer, and water retaining agent were applied, and the soil was tilled with a rotary tiller to a depth of 40 cm. A 0.4 m deep planting pit was dug at the center of each subunit except the central subunit, such as Figure 7 Then, the module in the central subunit is cut down along the module cutting groove 3 using a cutting tool, the depth is 0.4m, and the green module after cutting is as follows Fig. 9 As shown, it can be used for the next unit; fill the remaining modules except the central module into each subunit, fill the gaps with part of the soil, and fill the remaining soil into the central subunit, as shown Figure 8 As shown, water thoroughly and fix; apply compound fertilizer in each subunit for topdressing in mid-March, June, September and December, and apply Thiobacillus thiooxidans microbial agent in the central module of each subunit in mid-March, May and July, the method is the same as step (3); The front view and top view of the cutting tool are respectively as follows: Fig.11 and Fig.12 As shown, it includes a handle 4 with a length of about 20 cm, which is convenient for gripping, an upper width of a link part 5 of 2 cm for welding with the handle 4, a lower width of 1 cm, which can be just stuck at the bottom of this part during cutting, which is convenient for exerting force, and a cutting blade 6; (6) After that, the greening of each unit is initially completed and normal agronomic management is carried out; at the end of the third year, the coverage rate of each unit is above 90%, and the greening is basically completed. Fig.10 As shown, measure the central module of each unit (1m 2 ) were used to analyze the lead accumulation and biomass of each bamboo species in the experiment. The results are shown in Table 1.

[0028] Table 1 Biomass and lead accumulation of each bamboo species in the central module of each unit after three years of planting

[0029] As shown in Table 1, the lead accumulation of Indocalamus fulva and Indocalamus dwarfus has the highest amount, while the biomass of Indocalamus fulva and Indocalamus rubra is the largest. Therefore, Indocalamus fulva can be selected as the preferred bamboo species for this technology. Example 2

[0030] The experiment in this embodiment is located in the Fuquan lead-zinc mining area in Hanyuan County, Ya'an City, Sichuan Province, which belongs to the Tangjia-Wusi River lead-zinc mining belt. After years of mining, a large number of tailings ponds have been formed, causing serious damage to the surrounding ecological environment. The average lead content of the soil in the tailings pond of the test site is 1551.91±853.40mg / kg.

[0031] The repair method for the tailings pond includes the following steps: (1) Establish a 9×9m reforestation unit in the selected area of ​​the tailings pond, and further divide it into 9 sub-units, each of which is 3×3m in size. Clean the soil surface, remove large pieces of gravel and grass, and level the land. Set up 4 reforestation units in total; (2) Cover the soil surface of the regreening unit with 10 cm of soil, apply biological organic fertilizer and water retaining agent to the central unit, and then use a rotary tiller to plow the soil of the entire regreening unit to a depth of 40 cm; The specific composition of the bio-organic fertilizer is N:P:K=4:1:2, the organic matter content is 40%, and the dosage is 90g / m 2 , the application amount per unit is 7.29kg; The water-retaining agent is a super absorbent resin (SAPs), and the dosage is 2kg / m 2 , the application amount per unit is 162kg; (3) Select two-year-old bamboo planting materials that grow rapidly, have strong adaptability, and have the ability to absorb heavy metals, and transplant them into 1×1×0.4m planting modules in February. The bamboo whip length in the module is 1~1.5m, and the number of standing plants is 60~80 (so there is only beautiful bamboo here); then dig a 0.4m deep planting pit in the central sub-unit, place the module planted with bamboo in the center, and fill the sub-unit with 8 empty modules, then backfill the soil and water it thoroughly. After completion, carry out normal watering and weeding maintenance; apply compound fertilizer in each module for topdressing in mid-March, June, September, and December, and apply microbial agents in the central module in mid-March, May, and July. At the same time, set a unit as a control without applying microbial agents; The indocalamus described is indocalamus fasciata.

[0032] The topdressing method is to apply compound fertilizer in the range of 20 cm from the edge of the central module to the center in mid-March and June, and apply compound fertilizer evenly in other modules; the composition of compound fertilizer is nitrogen: phosphorus: potassium = 4:1:2, the organic matter content is 40%, and the dosage is 75g / m²; in mid-September and December, compound fertilizer is evenly applied in other modules except the central module; the composition of compound fertilizer is nitrogen: phosphorus: potassium = 4:1:2, the organic matter content is 40%, and the dosage is 75g / m²; The bacterial species of the microbial agents applied by each unit in the central module are Thiobacillus thiooxidans ( Thiobacillus thiooxidans )、Bacillus subtilis( Bacillus subtilis )、Bacillus megaterium( Bacillus megaterium ) and no microbial agent (blank), the application time was mid-March, May, and July, and the bacterial solution concentration was 1×10 8 CFU / mL, the method of use is to spray evenly on the soil surface around the central module of Indocalamus, the dosage is 100mL, and the unit without microbial agent is replaced with an equal amount of deionized water; (4) In December, the above-ground old bamboos of the central module were cut, and the cut bamboo leaves and bamboo stalks were collected and crushed. The crushed bamboo leaves were composted and fermented to produce bamboo leaf fertilizer, and the bamboo stalks were prepared as biochar; (5). In February of the following year, cover the surface of the contaminated soil in the subunits other than the central subunit with 10 cm of soil, apply bamboo leaf fertilizer, bamboo stalk biochar, biological organic fertilizer, and water retaining agent, and use a rotary tiller to plow the soil to a depth of 40 cm. Dig a 0.4 m deep planting pit at the center of each subunit except the central subunit at 1×1 m. Then, use a special cutting tool to cut the module in the central subunit down along the cutting groove of the module itself to a depth of 0.4 m. Fill the remaining modules except the central module into each subunit, fill the gaps with part of the soil, and fill the remaining soil into the central subunit, and water it thoroughly to fix it. Apply compound fertilizer to each subunit for topdressing in March, June, September, and mid-December, and apply microbial agents or an equal amount of deionized water to the central module of each subunit in mid-March, May, and July, using the same method as step (3); (6) After that, the greening of each unit was initially completed and normal agronomic management was carried out. At the end of the third year, the coverage rate of each unit was above 90%, and the greening was basically completed; the measurement center module (1m 2 ) were used to measure the lead accumulation and biomass of Indocalamus sibiricus in the experiment. The results are shown in Table 2.

[0033] Table 2 Biomass and lead accumulation of Indocalamus sibiricus in the central module of each unit after three years of planting

[0034] As can be seen from Table 2, Thiobacillus thiooxidans has the most obvious effect on promoting plant growth and lead accumulation, so it is used as the preferred species of microbial agent in this technology.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for repairing a lead-zinc tailings pond using Indigofera truncatula, characterized in that: The steps include: (1) Establishment of reforestation unit: Establish a reforestation unit in the selected area of ​​the tailings pond and divide it into at least three sub-units; (2) Soil improvement in the first year: Cover the contaminated soil surface of the entire regreening unit with soil, apply biological organic fertilizer and water-retaining agent to the sub-unit located in the middle, and use a rotary tiller to plow the soil of the entire regreening unit; (3) Indocalamus chinensis planting: Select Indocalamus chinensis planting materials, transplant them into planting modules, and then apply compound fertilizer as topdressing in each module and apply microbial agents; (4) Winter mowing: mowing the old bamboos above ground in the central module. (5) soil improvement and expansion of regreening areas within the unit in the second year; (6) After that, the unit will be initially regreened and normal agronomic management will be carried out, which will form a good landscape effect after 1 to 2 years. The planting modules in the unit can be removed and reused after the regreening is completed.

2. The method according to claim 1, characterized in that In step (1), the size of each regreening unit is 7.2×7.2~10.8×10.8m, and the sub-units are nine of the same size, each of which is 2.4×2.4~3.6×3.6m in size.

3. The method according to claim 1, characterized in that In step (2), the specific components and dosage of the bio-organic fertilizer are: nitrogen: phosphorus: potassium = 3:1:2~4:1:2, the organic matter content is 25~40%, the dosage is 60~90g / m², and the application amount per unit is 4.86~7.29kg; the water retaining agent is a highly absorbent resin SAPs, the dosage is 1~2kg / m², and the application amount per unit is 81~162kg.

4. The method according to claim 1, characterized in that In step (3), the compound fertilizer is applied in the middle of March, June, September and December, for a total of 4 times, wherein compound fertilizer is applied along the edges of the central module within 20 cm from the center in March and June, and compound fertilizer is applied evenly to the other modules normally; in September and December, compound fertilizer is evenly applied to the modules except the central module, and the composition of the compound fertilizer is nitrogen: phosphorus: potassium = 3:1:2~4:1:2, the organic matter content is 25~40%, and the dosage is 60~75g / m²; the microbial agent is selected from Bacillus subtilis ( Bacillus subtilis )、Bacillus megaterium( Bacillus megaterium ), Thiobacillus thiooxidans ( Thiobacillus thiooxidans ) with a content of 1×10 8 ~1×10 9 CFU / mL, the application method is to spray evenly on the soil surface around the central module of Indocalamus, the dosage is 100~500mL, the application time is mid-March, May and July, and the microbial agent is applied 3 times in total.

5. The method according to claim 1, characterized in that: The microorganism is Thiobacillus thiooxidans.

6. The method according to claim 1, characterized in that In step (3), the indocalamus is indocalamus fasciata.

7. The method according to claim 1, characterized in that In step (3), the specifications of the planting module are 0.8×0.8×0.5~1.2×1.2×0.5m, and iron rings are set at the four corners of the top surface, and are set around the four sides and the top.

8. The method according to claim 1, characterized in that In step (3), the length of the transplanted bamboo in the planting module is 1-1.5 m, and the number of standing plants is 40-80.

9. The method according to claim 1, characterized in that: In step (4), the cut old bamboo is crushed, the crushed bamboo leaves are used to prepare bamboo leaf fertilizer, and the bamboo stalks are used to prepare biochar and used for soil improvement in the second year.

10. The method according to claim 1, characterized in that In step (5), the specific method for improving the soil and expanding the greening area in the unit is as follows: covering the surface of the contaminated soil in the subunits other than the middle subunit with soil, applying bamboo leaf fertilizer, bamboo stalk biochar, biological organic fertilizer, and water retaining agent, and tilling the soil with a rotary tiller to a depth of 40 cm, digging a 0.4 m deep planting pit at the center of each subunit except the middle subunit at 1×1 m, cutting the module in the middle subunit along the cutting groove of the module itself with a special cutting tool to a depth of 0.4 m, filling it into the subunit and watering it thoroughly to fix it; applying compound fertilizer in each subunit for topdressing in March, June, September, and mid-December, and applying microbial agents in the central module of each subunit in mid-March, May, and July, in the same manner as step (3).

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