Method for improving saline-alkali soil in Sagomean region

Abstract

The invention relates to the field of soil improvement, and provides a method for improving saline-alkali soil in a Sagolian region. The method comprises the following steps that an isolation layer, an improvement layer, a water retention layer and a planting layer are sequentially arranged on the saline-alkali soil to be treated from bottom to top; the isolating layer comprises a thermal power solid waste slag layer and a hay layer which are arranged in a stacked mode. A sand barrier is arranged on the planting layer. The saline-alkali soil in the Sagomean area is improved in a sand barrier and soil layering composite mode. The sand barrier has the effects of increasing ground roughness and reducing erosion of wind power to a sand surface, so that the sand content in sand flow is reduced, the sand surface is effectively fixed, and wind erosion is reduced. The isolation layer, the improvement layer, the water retention layer and the planting layer are arranged in a stacked mode, desertification control is achieved, soil conditions are improved, and vegetation growth is promoted. The sand barrier and the soil layering cooperate with each other, the sand barrier can effectively protect the soil layering, and the survival rate and the growth quality of vegetation are improved.

Description

Technical Field

[0001] The present invention relates to the field of soil improvement, and particularly to a method for improving saline-alkali land in sandy and desertified areas. Background Art

[0002] The problems of land desertification and sandification are the most serious ecological problems and are the key points and difficulties in implementing regional ecological restoration. As an emerging strategy, building a photovoltaic power station in desertified areas can not only play a role in sand barriers to weaken the wind speed, but also play a role in shading the ground surface, effectively reducing its water evaporation, and contributing to the accumulation of water in the sandy soil. However, the surface sand blowing in desert areas will affect the power generation efficiency of photovoltaic panels and is prone to sandstorm disasters.

[0003] At present, the method of planting sand barriers + sowing mixed grass seeds is generally used for vegetation restoration, which has a lower cost. However, the existing sand barriers mainly fix the sandy soil through physical blocking and cannot play a role in vegetation restoration. After directly sowing mixed grass seeds, the vegetation restoration effect is poor, and the overall restoration period is long (3 - 5 years). It is still difficult to achieve ideal results in desert and desert areas with drought, water shortage, high land salinity, and poor water and fertilizer retention capacity. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the problems of poor anti-sand and anti-wind erosion improvement effects and long vegetation restoration period of saline-alkali land in sandy and desertified areas in the prior art, and to provide a method for improving saline-alkali land in sandy and desertified areas.

[0005] For this purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a method for improving saline-alkali land in sandy and desertified areas, including the following steps:

[0007] On the saline-alkali land to be treated, a separation layer, an improvement layer, a water retention layer, and a planting layer are sequentially arranged from bottom to top; the separation layer includes a thermal power solid waste slag layer and a hay layer arranged in a stacked manner;

[0008] A sand barrier is arranged on the planting layer.

[0009] The hay layer in the separation layer can isolate the saline water vapor in the soil and reduce the migration of salts to the improvement layer. At the same time, the hay layer can increase the organic matter and nutrient element content of the soil. After being decomposed by microorganisms, it can improve the soil structure, increase the porosity and air permeability of the soil, promote the growth and development of plant roots, and improve the biological activity and fertility of the soil. The thermal power solid waste slag layer can improve the soil structure and drainage.

[0010] The laminated arrangement of the hay layer and the thermal power solid waste slag layer can produce a synergistic effect, which can more effectively isolate the salts and moisture in the soil and reduce the impact of salts on the improvement layer. In addition, the addition of hay can also improve the water retention capacity of the soil and reduce water evaporation. This arrangement can further ensure that the improvement layer is not affected by the salinity of the ground layer and improve the soil improvement level.

[0011] In an optional embodiment, the side of the isolation layer close to the saline-alkali land to be treated and / or close to the improvement layer is a hay layer.

[0012] In an optional embodiment, the sand barrier is a composite sand barrier, including a straw checkerboard sand barrier and an environmentally friendly permeable brick sand barrier.

[0013] Preferably, the environmentally friendly permeable bricks in the environmentally friendly permeable brick sand barrier contain the following parts by mass of preparation raw materials: 10-12 parts of fly ash, 10-12 parts of red mud, 10-12 parts of sludge, 20-24 parts of coal gangue, 20-25 parts of construction waste, and 30-35 parts of epoxy resin powder.

[0014] The present invention uses the combination of environmentally friendly permeable bricks and straw checkers to improve the soil structure, promote the increase of vegetation coverage, improve the saline-alkali land environment, and provide a more comprehensive effect of desert control and saline-alkali land improvement. The composite sand barrier of this application not only includes the function of physically blocking wind and sand, but also realizes the improvement of soil structure and physical and chemical properties, as well as the restoration and growth of vegetation by combining the improvement layer and the planting layer, thereby promoting ecological restoration and soil health while preventing wind and sand erosion.

[0015] The environmentally friendly permeable bricks utilize their water permeability principle to allow water to penetrate, reduce surface runoff, and increase groundwater recharge. At the same time, the environmentally friendly permeable bricks made of industrial waste have the functions of water retention and ecological restoration while reducing production costs and energy consumption, which is helpful for vegetation growth and soil microbial activities. In addition, by increasing the use of epoxy resin powder, the strength and durability of the environmentally friendly permeable bricks can be ensured without sacrificing their mechanical properties. The present invention carefully optimizes the raw materials to make the environmentally friendly permeable bricks more suitable for saline-alkali land improvement work, while promoting the reuse of large amounts of solid waste and achieving a win-win situation for environmental and economic benefits.

[0016] In an optional embodiment, the preparation method of the environmentally friendly permeable bricks includes the following steps:

[0017] Mix fly ash, red mud and coal gangue, and calcine to obtain a mixture; mix the mixture, sludge, construction waste and epoxy resin powder, pour them into a mold for molding, and perform curing after molding to obtain the environmentally friendly permeable bricks.

[0018] Preferably, the particle size of the construction waste ≤ 1 cm.

[0019] Preferably, the calcination temperature is 500 - 600 °C and the time is 1 - 2 h.

[0020] After the calcination is completed, it is naturally cooled to room temperature to obtain a mixture.

[0021] Preferably, the forming method is drying, the drying temperature is 20 - 30 °C, and the time is 24 - 48 h.

[0022] Preferably, the curing temperature is 30 - 40 °C, the humidity is 55 - 60%, and the time is 44 - 52 h.

[0023] In an alternative embodiment, on the planting layer, setting up a composite sand barrier includes the following steps:

[0024] The planting layer is evenly divided into n square planting layers, where n > 0, and the side length of the square planting layer is 2.5 - 3.5 m; taking any one square planting layer as a unit, environmental protection permeable brick sand barriers are set at the four sides of the square planting layer, and the square planting layer is evenly divided into nine small square units. Environmental protection permeable brick sand barriers are set at the four sides of the square unit located in the center, and straw checkerboard sand barriers are set at the positions of other dividing lines of the square planting layer.

[0025] Through the above - mentioned specific sand barrier design, it helps to more effectively reduce the wind speed, reduce wind erosion, fix sand, and at the same time improve the soil micro - environment, creating more favorable conditions for vegetation restoration.

[0026] In an alternative embodiment, the height of the straw checkerboard sand barrier and the environmental protection permeable brick sand barrier above the planting layer is independently 15 - 20 cm, and the depth below the planting layer is independently 13 - 17 cm.

[0027] By selecting sand barriers with specific heights, the anti - sand effect is further improved, and sand and wind can be effectively blocked.

[0028] The present invention does not specifically limit the width of the sand barrier.

[0029] In an alternative embodiment, the thickness of the isolation layer is 7 - 10 cm.

[0030] Preferably, the total number of layers of the thermal power solid waste slag layer and the hay layer in the isolation layer ≥ 3 layers, preferably 5 - 7 layers.

[0031] Preferably, the thicknesses of each thermal power solid waste slag layer and hay layer do not need to be equal, as long as the ratio of the total thickness of the thermal power solid waste slag layer to the total thickness of the hay layer in the isolation layer is 0.5 - 1.5:0.5 - 1.5.

[0032] In an alternative embodiment, the thickness of the improvement layer is 32 - 40 cm; the improvement layer is a mixture of ceramsite and the surface soil of the saline - alkali land.

[0033] Preferably, the mass ratio of ceramsite to the saline-alkali soil surface layer in the improvement layer is 1:2 - 2.5.

[0034] In an alternative embodiment, the raw materials for preparing ceramsite are bulk solid wastes.

[0035] Preferably, the ceramsite contains the following parts by mass of raw materials for preparation: 45 - 51 parts of sludge incineration ash, 30 - 34 parts of fly ash, and 15 - 25 parts of clay.

[0036] In an alternative embodiment, the method for preparing ceramsite comprises the following steps:

[0037] Mix the raw materials of ceramsite and add water to obtain a mixed material; granulate, dry, and roast the mixed material in sequence to obtain ceramsite.

[0038] Before mixing the raw materials for preparation, independently subject each raw material for preparation to drying treatment and manual grinding in sequence. After manual grinding, sieve it, and then mix; preferably, the mesh number of the sieve for sieving ≤ 200 meshes.

[0039] Preferably, the moisture content of the mixed material is 25 - 30%.

[0040] The moisture content refers to the ratio of the mass of water in the mixed material to the total mass of the mixed material.

[0041] Preferably, the particle size of the sample obtained by granulation is 5 - 10 mm.

[0042] Preferably, the drying temperature is 100 - 110 °C and the time is 35 - 45 min.

[0043] In an alternative embodiment, roasting includes the following steps: heating the sample obtained by drying from room temperature to an intermediate temperature, and then heating from the intermediate temperature to the target temperature for roasting, and carrying out heat preservation.

[0044] Preferably, the intermediate temperature is 320 - 380 °C, and the heating time from room temperature to the intermediate temperature is 35 - 40 min.

[0045] Preferably, the heating time from the intermediate temperature to the target temperature for roasting is 13 - 17 min.

[0046] Preferably, the target temperature for roasting is 1000 - 1100 °C, and the heat preservation time after reaching the target temperature is 10 - 20 min.

[0047] The heating process of roasting is a progressive heating, which can avoid stress cracks caused by the rapid evaporation of moisture in the raw materials.

[0048] In an alternative embodiment, the thickness of the water retention layer is 5 - 8 cm.

[0049] Optionally, the water retention layer is hydrothermally synthesized from fly ash, red mud and carbide slag.

[0050] Preferably, the mass ratio of fly ash, red mud and carbide slag is 2.5 - 3.5:1.5 - 2.5:1.5 - 2.5.

[0051] Preferably, the temperature of hydrothermal synthesis is 80 - 90 °C, the liquid - solid ratio is 3 - 6:1, and the time is 7 - 9 h.

[0052] In an alternative embodiment, the thickness of the planting layer is 12 - 16 cm.

[0053] Optionally, the planting layer is a mixture of stockpiled and aged fly ash, well - decomposed animal manure, and anaerobic fermentation residue of sludge.

[0054] The mixture of stockpiled and aged fly ash, well - decomposed animal manure and anaerobic fermentation residue of sludge as the planting layer can provide rich organic matter and nutrient elements, increase soil fertility, and promote plant growth.

[0055] Preferably, the mass ratio of stockpiled and aged fly ash, well - decomposed animal manure and anaerobic fermentation residue of sludge is 1.5 - 2.5:4.5 - 5.5:0.5 - 1.5.

[0056] Preferably, the stockpiling and aging time of the stockpiled and aged fly ash is 2 - 4 months.

[0057] Preferably, it is stockpiled and aged for 2 months in summer and 4 months in winter.

[0058] The technical solution of the present invention has the following advantages:

[0059] 1. The present invention provides a method for improving saline - alkali land in sandy and desertified areas, including the following steps: on the saline - alkali land to be treated, a barrier layer, an improvement layer, a water retention layer and a planting layer are sequentially arranged from bottom to top; the barrier layer includes a thermal power solid waste slag layer and a hay layer arranged in a stacked manner; on the planting layer, a sand barrier is arranged.

[0060] The present invention uses a composite method of sand barrier + soil layering to improve the saline - alkali land in sandy and desertified areas. The sand barrier plays a role in increasing the ground roughness, reducing the erosion of the sand surface by wind, thereby reducing the sand content in the sand - wind flow, effectively fixing the sand surface, and reducing wind erosion. The stacked barrier layer, improvement layer, water retention layer and planting layer not only control sand but also improve soil conditions and promote vegetation growth. The sand barrier and soil layering cooperate with each other. The sand barrier can effectively protect the soil layering and improve the survival rate and growth quality of vegetation.

[0061] The isolation layer comprises a thermoelectric solid waste slag layer and a hay layer arranged in a stacked manner. The hay layer in the isolation layer can isolate the saline water vapor in the soil and reduce the migration of salts to the improvement layer. At the same time, the hay layer can increase the organic matter and nutrient element content of the soil. After being decomposed by microorganisms, it can improve the soil structure, increase the porosity and air permeability of the soil, promote the growth and development of plant roots, and improve the biological activity and fertility of the soil. The thermoelectric solid waste slag layer can improve the soil structure and drainage performance.

[0062] The stacked arrangement of the hay layer and the thermoelectric solid waste slag layer can produce a synergistic effect, which can more effectively isolate the salts and moisture in the soil and reduce the impact of salts on the improvement layer. In addition, the addition of hay can also improve the water retention capacity of the soil and reduce water evaporation. This setting can further ensure that the improvement layer is not affected by the salinity of the ground layer and improve the soil improvement level.

[0063] Through the improvement measures of the present invention, the improvement effect of saline-alkali land is improved, the ecological function and agricultural production potential of the soil are enhanced, the sustainable development of soil improvement is realized, and good environmental and economic benefits are obtained. The saline-alkali land improved by the present invention can significantly improve the vegetation coverage rate and growth conditions, and improve the vegetation diversity and ecological stability.

[0064] 2. The sand barrier is a composite sand barrier, which comprises a straw checkerboard sand barrier and an environmentally friendly permeable brick sand barrier; the environmentally friendly permeable bricks in the environmentally friendly permeable brick sand barrier comprise the following parts by mass of preparation raw materials: 10-12 parts of fly ash, 10-12 parts of red mud, 10-12 parts of sludge, 20-24 parts of coal gangue, 20-25 parts of construction waste, and 30-35 parts of epoxy resin powder. The present invention uses the combination of environmentally friendly permeable bricks and straw checkerboards, which can improve the soil structure, promote the increase of vegetation coverage, improve the saline-alkali land environment, and provide a more comprehensive desert control and saline-alkali land improvement effect. The composite sand barrier of the present application not only includes the function of physically blocking wind and sand, but also realizes the improvement of soil structure and physical and chemical properties, as well as the restoration and growth of vegetation by combining the improvement layer and the planting layer. Therefore, while preventing wind and sand erosion, it promotes ecological restoration and soil health. The environmentally friendly permeable bricks utilize their water permeability principle to allow water to penetrate, reduce surface runoff, and increase groundwater recharge. At the same time, the environmentally friendly permeable bricks made of industrial waste have the functions of water retention and ecological restoration while reducing production costs and energy consumption, which is helpful for vegetation growth and soil microbial activities. In addition, by increasing the use of epoxy resin powder, the strength and durability of the environmentally friendly permeable bricks can be ensured without sacrificing their mechanical properties. The present invention carefully optimizes the raw materials to make the environmentally friendly permeable bricks more suitable for saline-alkali land improvement work, and at the same time promotes the reuse of bulk solid waste, achieving a win-win situation for environmental and economic benefits.

[0065] 3. On the planting layer, setting up the composite sand barrier includes the following steps: evenly divide the planting layer into n square planting layers, where n > 0, and the side length of the square planting layer is 2.5 - 3.5 m; taking any one square planting layer as a unit, set environmental protection permeable brick sand barriers at the four sides of the square planting layer, and evenly divide the square planting layer into nine small square units. Set environmental protection permeable brick sand barriers at the four sides of the central square unit, and set straw checkerboard sand barriers at other dividing line positions of the square planting layer; the height of the straw checkerboard sand barriers and the environmental protection permeable brick sand barriers above the planting layer is independently 15 - 20 cm, and the depth below the planting layer is independently 13 - 17 cm. Through the above specific sand barrier design, it helps to more effectively reduce the wind speed, reduce wind erosion, fix sand, and at the same time improve the soil microenvironment, creating more favorable conditions for vegetation restoration. By selecting sand barriers with specific heights, the anti-sand effect is further enhanced, and sand and dust can be effectively blocked.

[0066] 4. The planting layer is a mixture of stockpiled and aged fly ash, decomposed and fermented animal manure, and anaerobic fermentation residues of sludge. The mixture of stockpiled and aged fly ash, decomposed and fermented animal manure, and anaerobic fermentation residues of sludge as the planting layer can provide rich organic matter and nutrient elements, increase soil fertility, and promote plant growth.

[0067] 5. The present invention uses industrial wastes such as thermal power solid waste slag, hay, ceramsite, fly ash, red mud, and carbide slag as modifiers together. The various solid wastes cooperate with each other. The diversified utilization of bulk solid wastes not only improves the comprehensive utilization rate of resources, but also can improve the physical, chemical, and biological properties of the soil from different angles, realizing more comprehensive soil improvement. The provided organic matter and nutrient elements can promote soil microbial activities, reduce the soil pH value, reduce soil salinity, improve the water retention and air permeability of the soil, and thus are beneficial to plant growth. Brief Description of the Drawings

[0068] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0069] Figure 1 It is a schematic diagram of the sand barrier layout of the square planting layer in Embodiment 1 of the present invention; Figure 1 In it, 1 is the environmental protection permeable brick sand barrier, and 2 is the straw checkerboard sand barrier;

[0070] Figure 2 It is a schematic diagram of the soil structure of the improved saline-alkali land in Embodiment 1 of the present invention.Figure 2 Among them, 3 is the saline-alkali land to be treated, 4 is the isolation layer, 5 is the improvement layer, 6 is the water retention layer, and 7 is the planting layer. Specific implementation method

[0071] The following embodiments are provided to better understand the present invention further. It is not limited to the best implementation mode, and does not constitute a limitation to the content and protection scope of the present invention. Any product that is the same as or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior art features falls within the protection scope of the present invention.

[0072] For those embodiments in which specific experimental steps or conditions are not indicated, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. For the reagents or instruments whose manufacturers are not indicated, they are all conventional reagent products that can be obtained through commercial purchase.

[0073] Example 1

[0074] This embodiment provides a method for improving saline-alkali land in sandy and barren areas, including the following steps:

[0075] On the saline-alkali land to be treated, an isolation layer, an improvement layer, a water retention layer, and a planting layer are sequentially arranged from bottom to top;

[0076] The thickness of the isolation layer is 7 cm, and it includes a stacked thermal power solid waste slag layer and a hay layer. The total number of layers is 7. The sides of the isolation layer close to the saline-alkali land to be treated and the improvement layer are both hay layers. The ratio of the total thickness of the thermal power solid waste slag layer to the total thickness of the hay layer is 1:1;

[0077] The thickness of the improvement layer is 35 cm, and it is a mixture of ceramsite and the surface soil of saline-alkali land (the mass ratio of ceramsite to the surface soil of saline-alkali land is 1:2.2). The ceramsite contains the following mass parts of preparation raw materials: 48 parts of sludge incineration ash, 32 parts of fly ash, and 20 parts of clay; the preparation method of the ceramsite includes the following steps: drying each preparation raw material independently and sequentially, manually grinding, passing through a 200-mesh sieve after manual grinding, then mixing, and adding water to obtain a mixed material with a moisture content of 27%; granulating the mixed material to obtain a sample with a particle size of 8 mm, then drying at 105 °C for 40 min, and finally roasting. The roasting process is set as follows: first heating from room temperature to 350 °C (heating time is 37 min), then heating from 350 °C to 1050 °C (heating time is 15 min), setting the holding time at 1050 °C to 15 min to obtain the ceramsite;

[0078] The thickness of the water retention layer is 7 cm, and it is synthesized by hydrothermal synthesis of fly ash, red mud, and carbide slag. The mass ratio of fly ash, red mud, and carbide slag is 3:2:2. The temperature of hydrothermal synthesis is 85 °C, the liquid-solid ratio is 5:1, and the time is 8 h;

[0079] The thickness of the planting layer is 12 cm, which is a mixture of fly ash stockpiled and aged for 2 months in summer, fermented and decomposed animal manure, and anaerobic fermentation residue of sludge (the mass ratio of fly ash, fermented and decomposed animal manure, and anaerobic fermentation residue of sludge after stockpiling and aging is 2:5:1).

[0080] On the planting layer, a composite sand barrier is set (the composite sand barrier includes a straw checkerboard sand barrier 2 and an environmentally friendly permeable brick sand barrier 1): the planting layer (with a length * width of 9 m * 9 m) is evenly divided into 9 square planting layers with a side length of 3 m; taking any one square planting layer as a unit, an environmentally friendly permeable brick sand barrier 1 is set at the positions of the four sides of the square planting layer, and the square planting layer is evenly divided into nine small square units. An environmentally friendly permeable brick sand barrier 1 is set at the positions of the four sides of the square unit located in the center, and a straw checkerboard sand barrier 2 is set at other dividing line positions; the heights of the straw checkerboard sand barrier 2 and the environmentally friendly permeable brick sand barrier 1 above the planting layer are both 16 cm, and the depths below the planting layer are both 15 cm; specifically, the schematic diagram of the sand barrier layout of the square planting layer in this embodiment is as Figure 1 shown; Figure 1 In the figure, 1 is the environmentally friendly permeable brick sand barrier, and 2 is the straw checkerboard sand barrier.

[0081] Among them, the environmentally friendly permeable bricks in the above-mentioned environmentally friendly permeable brick sand barrier contain the following mass parts of preparation raw materials: 11 parts of fly ash, 11 parts of red mud, 11 parts of sludge, 22 parts of coal gangue, 23 parts of construction waste with a particle size ≤ 1 cm, and 33 parts of epoxy resin powder; the preparation method of the environmentally friendly permeable bricks includes the following steps: mix fly ash, red mud, and coal gangue, and calcine at 550 °C for 1.5 h. After the calcination is completed, naturally cool to room temperature to obtain a mixture; mix the mixture, sludge, construction waste, and epoxy resin powder, pour it into a mold for molding (the molding method is drying, the drying temperature is 25 °C, and the time is 36 h). After the molding is completed, carry out curing, set the curing temperature to 35 °C, the humidity to 57%, and the time to 48 h to obtain the environmentally friendly permeable bricks.

[0082] The schematic diagram of the soil structure of the improved saline-alkali land in this embodiment is as Figure 2 shown. On the saline-alkali land 3 to be treated, a separation layer 4, an improvement layer 5, a water retention layer 6, and a planting layer 7 are sequentially arranged from bottom to top.

[0083] Example 2

[0084] This embodiment provides a method for improving saline-alkali land in the sandy gobi desert area, including the following steps:

[0085] On the saline-alkali land to be treated, a separation layer, an improvement layer, a water retention layer, and a planting layer are sequentially arranged from bottom to top;

[0086] The thickness of the isolation layer is 9 cm, which includes a thermal power solid waste slag layer and a hay layer arranged in layers. The total number of layers is 5. The sides of the isolation layer close to the saline-alkali land to be treated and the improvement layer are both hay layers. The ratio of the total thickness of the thermal power solid waste slag layer to the total thickness of the hay layer is 1:1.2;

[0087] The thickness of the improvement layer is 39 cm, which is a mixture of ceramsite and saline-alkali surface soil (the mass ratio of ceramsite to saline-alkali surface soil is 1:2). The ceramsite contains the following mass parts of preparation raw materials: 45 parts of sludge incineration ash, 30 parts of fly ash, and 15 parts of clay; The preparation method of the ceramsite includes the following steps: drying each preparation raw material independently and sequentially, manually grinding, passing through a 200-mesh sieve after manual grinding, then mixing, and adding water to obtain a mixed material with a moisture content of 25%; granulating the mixed material to obtain a sample with a particle size of 6 mm, then drying at 100 °C for 45 min, and finally roasting. The roasting process is set as follows: first, heat up from room temperature to 330 °C (heating time is 35 min), then heat up from 330 °C to 1000 °C (heating time is 15 min), set the holding time at 1000 °C to 20 min to obtain the ceramsite;

[0088] The thickness of the water retention layer is 8 cm, which is hydrothermally synthesized from fly ash, red mud, and carbide slag. The mass ratio of fly ash, red mud, and carbide slag is 2.5:1.5:1.5. The hydrothermal synthesis temperature is 80 °C, the liquid-solid ratio is 3:1, and the time is 9 h;

[0089] The thickness of the planting layer is 15 cm, which is a mixture of fly ash stored and aged in winter for 4 months, fermented and decomposed animal manure, and sludge anaerobic fermentation residue (the mass ratio of fly ash, fermented and decomposed animal manure, and sludge anaerobic fermentation residue after storage and aging is 1.5:4.5:0.5).

[0090] On the planting layer, a composite sand barrier is set (the composite sand barrier includes a straw checkerboard sand barrier and an environmentally friendly permeable brick sand barrier): The planting layer (length * width is 15 m * 12 m) is evenly divided into 20 square planting layers with a side length of 3 m; Taking any one square planting layer as a unit, environmentally friendly permeable brick sand barriers are set at the four sides of the square planting layer, and the square planting layer is evenly divided into nine small square units. Environmentally friendly permeable brick sand barriers are set at the four sides of the central square unit, and straw checkerboard sand barriers are set at other dividing line positions; The heights of the straw checkerboard sand barrier and the environmentally friendly permeable brick sand barrier above the planting layer are both 15 cm, and the depths below the planting layer are both 15 cm;

[0091] Among them, the environmentally friendly permeable brick in the above-mentioned environmentally friendly permeable brick sand barrier contains the following parts by mass of preparation raw materials: 10 parts of fly ash, 10 parts of red mud, 10 parts of sludge, 20 parts of coal gangue, 20 parts of construction waste with a particle size ≤ 1 cm, and 30 parts of epoxy resin powder; the preparation method of the environmentally friendly permeable brick includes the following steps: Mix fly ash, red mud and coal gangue, and calcine at 500 °C for 2 h. After the calcination is completed, cool naturally to room temperature to obtain a mixture; Mix the mixture, sludge, construction waste and epoxy resin powder, pour it into a mold and form (the forming method is drying, the drying temperature is 28 °C, and the time is 28 h). After the forming is completed, carry out curing, set the curing temperature to 30 °C, the humidity to 55%, and the time to 52 h to obtain the environmentally friendly permeable brick.

[0092] Example 3

[0093] This example provides a method for improving saline-alkali land in sandy gobi areas, including the following steps:

[0094] On the saline-alkali land to be treated, a separation layer, an improvement layer, a water retention layer and a planting layer are sequentially arranged from bottom to top;

[0095] The thickness of the separation layer is 8 cm, and it includes a thermal power solid waste slag layer and a hay layer arranged in layers. The total number of layers is 7. The sides of the separation layer close to the saline-alkali land to be treated and the improvement layer are both hay layers. The ratio of the total thickness of the thermal power solid waste slag layer to the total thickness of the hay layer is 1:1.5;

[0096] The thickness of the improvement layer is 37 cm, and it is a mixture of ceramsite and saline-alkali surface soil (the mass ratio of ceramsite to saline-alkali surface soil is 1:2.5). The ceramsite contains the following parts by mass of preparation raw materials: 51 parts of sludge incineration ash, 34 parts of fly ash and 25 parts of clay; the preparation method of the ceramsite includes the following steps: Independently and sequentially carry out drying treatment and manual grinding on each preparation raw material. After manual grinding, pass through a 200-mesh sieve, and then mix and add water to obtain a mixed material with a moisture content of 30%; Granulate the mixed material to obtain a sample with a particle size of 8 mm, then dry at 110 °C for 35 min, and finally carry out roasting. Set the roasting process as follows: First, heat up from room temperature to 360 °C (the heating time is 40 min), and then heat up from 360 °C to 1100 °C (the heating time is 17 min). Set the holding time at 1100 °C to 10 min to obtain the ceramsite;

[0097] The thickness of the water retention layer is 6 cm, and it is synthesized by hydrothermal reaction of fly ash, red mud and carbide slag. The mass ratio of fly ash, red mud and carbide slag is 3.5:2.5:2.5. The hydrothermal synthesis temperature is 90 °C, the liquid-solid ratio is 6:1, and the time is 7 h;

[0098] The thickness of the planting layer is 13 cm, which is a mixture of fly ash, decomposed and fermented animal manure, and anaerobic fermentation residue of sludge that has been stockpiled and aged for 4 months in winter (the mass ratio of fly ash, decomposed and fermented animal manure, and anaerobic fermentation residue of sludge after stockpiling and aging is 2.5:5.5:1.5).

[0099] On the planting layer, a composite sand barrier is set (the composite sand barrier includes a straw checkerboard sand barrier and an environmentally friendly permeable brick sand barrier): the planting layer (with a length * width of 18 m * 12 m) is evenly divided into 24 square planting layers with a side length of 3 m; taking any one square planting layer as a unit, environmentally friendly permeable brick sand barriers are set at the four sides of the square planting layer, and the square planting layer is evenly divided into nine small square units. Environmentally friendly permeable brick sand barriers are set at the four sides of the square unit located in the center, and straw checkerboard sand barriers are set at the positions of other dividing lines; the height of the straw checkerboard sand barrier and the environmentally friendly permeable brick sand barrier above the planting layer is 15.5 cm, and the depth below the planting layer is 15 cm;

[0100] Among them, the environmentally friendly permeable bricks in the above-mentioned environmentally friendly permeable brick sand barrier contain the following mass parts of preparation raw materials: 12 parts of fly ash, 12 parts of red mud, 12 parts of sludge, 24 parts of coal gangue, 25 parts of construction waste with a particle size ≤ 1 cm, and 35 parts of epoxy resin powder; the preparation method of the environmentally friendly permeable brick includes the following steps: mix fly ash, red mud, and coal gangue, and calcine at 600 °C for 1 h. After the calcination is completed, cool naturally to room temperature to obtain a mixture; mix the mixture, sludge, construction waste, and epoxy resin powder, pour them into a mold and form (the forming method is drying, the drying temperature is 22 °C, and the time is 45 h). After the forming is completed, carry out curing, set the curing temperature to 40 °C, the humidity to 60%, and the time to 44 h to obtain the environmentally friendly permeable brick.

[0101] Comparative Example 1

[0102] This comparative example provides a method for improving saline-alkali land in the Shagehuang area. The difference from Example 1 is only that no sand barrier is set on the planting layer.

[0103] Comparative Example 2

[0104] This comparative example provides a method for improving saline-alkali land in the Shagehuang area. The difference from Example 1 is only that no hay layer is set in the isolation layer, and it is only a thermal power solid waste slag layer.

[0105] Referring to the irrigation-arbor-herb 811 planting method (80% shrubs (Salix psammophila, Hippophae rhamnoides), 10% arbors (Ulmus pumila, Populus euphratica), 10% herbaceous plants and medicinal herbs (alfalfa, Chinese medicinal materials)), vegetation is planted on the improved saline-alkali land in Examples 1-3 and Comparative Examples 1-2, and the vegetation coverage test results of the improved saline-alkali land in Examples 1-3 and Comparative Examples 1-2 after 8 months are obtained, as shown in Table 1.

[0106] Table 1 Vegetation coverage test results of the improved saline-alkali land after 8 months in Examples 1-3 and Comparative Examples 1-2

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[0109] Obviously, the above examples are merely illustrations for clear explanation and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of this invention.

Claims

1. A method for improving saline-alkali land in Shagohuang area, characterized in that: The following steps are involved: On the saline-alkali land to be treated, an isolation layer, an improvement layer, a water-retaining layer and a planting layer are arranged in order from bottom to top; the isolation layer comprises a thermal power solid waste slag layer and a hay layer arranged in layers; On the planting layer, set up sand barriers.

2. The method for improving saline-alkali land in Shagohuang area according to claim 1, characterized in that: The side of the isolation layer close to the saline-alkali land to be treated and / or close to the improved layer is a hay layer.

3. The method for improving saline-alkali land in Shagohuang area according to claim 1, characterized in that: The sand barrier is a composite sand barrier, including a grass grid sand barrier and an environmentally friendly permeable brick sand barrier; Preferably, the environmentally friendly permeable bricks in the environmentally friendly permeable brick sand barrier contain the following raw materials in proportion by mass: 10-12 parts of fly ash, 10-12 parts of red mud, 10-12 parts of sewage sludge, 20-24 parts of coal gangue, 20-25 parts of construction waste and 30-35 parts of epoxy resin powder.

4. The method for improving saline-alkali land in Shagohuang area according to claim 3, characterized in that: The preparation method of environmentally friendly permeable bricks comprises the following steps: The fly ash, red mud and coal gangue are mixed and calcined to obtain a mixture; the mixture, sludge, construction waste and epoxy resin powder are mixed and poured into a mold for forming, and after the forming is completed, curing is performed to obtain an environmentally friendly permeable brick; Preferably, the particle size of the construction waste is ≤1 cm; Preferably, the calcination temperature is 500-600°C and the time is 1-2h; Preferably, the curing temperature is 30-40°C, the humidity is 55-60%, and the curing time is 44-52 hours.

5. The method for improving saline-alkali land in Shagohuang area according to claim 3, characterized in that: On the planting layer, setting up the composite sand barrier includes the following steps: The planting layer is evenly divided into n square planting layers, where n>0, and the side length of the square planting layer is 2.5-3.5m; any square planting layer is taken as a unit, and environmentally friendly permeable brick sand barriers are set at the four sides of the square planting layer, and the square planting layer is evenly divided into nine small square units, and environmentally friendly permeable brick sand barriers are set at the four sides of the square unit located in the center, and grass grid sand barriers are set at other dividing line positions of the square planting layer; Preferably, the height of the grass grid sand barrier and the environmentally friendly permeable brick sand barrier above the planting layer is independently 15-20 cm, and the depth below the planting layer is independently 13-17 cm.

6. The method for improving saline-alkali land in Shagohuang area according to claim 1, characterized in that: The thickness of the isolation layer is 7-10cm; Preferably, the ratio of the total thickness of the thermal power solid waste slag layer to the total thickness of the hay layer in the isolation layer is 0.5-1.5:0.5-1.

5.

7. The method for improving saline-alkali land in Shagohuang area according to claim 1, characterized in that: The thickness of the improved layer is 32-40cm; the improved layer is a mixture of ceramsite and saline-alkali surface soil; Preferably, the mass ratio of ceramsite in the improved layer to the saline-alkali surface soil is 1:2-2.5; Preferably, the ceramsite comprises the following raw materials in proportion by mass: 45-51 parts of sludge incineration ash, 30-34 parts of fly ash and 15-25 parts of clay.

8. The method for improving saline-alkali land in Shagohuang area according to claim 7, characterized in that: The preparation method of ceramsite comprises the following steps: The raw materials of ceramsite are mixed and water is added to obtain a mixed material; the mixed material is granulated, dried and roasted in sequence to obtain ceramsite; Preferably, the moisture content of the mixed material is 25-30%; Preferably, the particle size of the sample obtained by granulation is 5-10 mm; Preferably, the drying temperature is 100-110°C and the drying time is 35-45 minutes; Preferably, the target temperature of the calcination is 1000-1100° C., and the holding time after reaching the target temperature is 10-20 min.

9. The method for improving saline-alkali land in Shagohuang area according to claim 1, characterized in that: The thickness of the water-retaining layer is 5-8cm; Optionally, the water retention layer is hydrothermally synthesized using fly ash, red mud and carbide slag; Preferably, the mass ratio of fly ash, red mud and carbide slag is 2.5-3.5:1.5-2.5:1.5-2.5; Preferably, the temperature of the hydrothermal synthesis is 80-90°C, the liquid-solid ratio is 3-6:1, and the time is 7-9h.

10. The method for improving saline-alkali land in Shagohuang area according to claim 1, characterized in that: The thickness of the planting layer is 12-16cm; Optionally, the planting layer is a mixture of piled-up aged fly ash, decomposed and fermented animal manure, and anaerobic fermentation residue of sludge; Preferably, the mass ratio of the stored and aged fly ash, the fermented animal excrement and the anaerobic fermentation residue of the sludge is 1.5-2.5:4.5-5.5:0.5-1.5; Preferably, the storage and aging time of the fly ash after storage and aging is 2-4 months.

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