A step-by-step salt discharge and fixation method for improving saline-alkali soil by using multi-source sludge

Abstract

The application discloses a kind of gradient salt discharge solid salt method for improving saline-alkali soil by multi-source sludge, belongs to multi-source sludge resource utilization and saline-alkali soil remediation field.The gradient salt discharge solid salt method comprises a saline-alkali soil block, a salt discharge structure, a solid salt structure and a permeation salt discharge side chamber device.The application constructs three-layer salt discharge structure, forms different organic matter and soil mixture, so that the upper salt can seep downward, and the lower salt cannot reach the upper layer.The application can continuously discharge salt downward, and forms a complete saline-alkali soil structure.Water supply sludge contains a large amount of iron and aluminum salt, has strong adsorption and fixation capacity for nitrogen and organic matter, uses water supply sludge to fix the nutrient substances of compost product, so that the nutrient substances are not washed away by salt discharge water, and simultaneously solves the problem of poor water permeability of clay.The application provides a new type of gradient salt discharge solid salt method for saline-alkali soil, and fundamentally solves the problem of saline-alkali soil reclamation.

Description

Technical Field

[0001] This invention relates to the fields of multi-source sludge resource utilization and saline-alkali land soil remediation, and in particular to a tiered salt removal and salt fixation method for improving saline-alkali land using multi-source sludge. Background Technology

[0002] Soil salinization is a serious environmental problem with many adverse effects on crop growth. It disrupts normal metabolism. Excessive salt inhibits chlorophyll synthesis and the production of various enzymes in the photosynthetic apparatus, especially chlorophyll protein formation. Generally, crops grown in highly saline soils have a lower net photosynthetic rate than those in less saline soils. Excessive salt also affects plant respiration, often reducing it, although some plants require additional salt to improve respiration. Although the effects of excessive salt on photosynthesis and respiration differ, the overall trend is that respiration consumes more resources, resulting in lower net photosynthetic productivity and hindering plant growth.

[0003] When there is excessive soluble salt in the soil, the soil water potential decreases due to increased osmotic potential. According to the principle that water flows from high to low potential, the water potential of root cells must be lower than that of the surrounding medium to absorb water. Therefore, the higher the salt content in the soil, the more difficult it is for the roots to absorb water, and there is even a risk of water leakage from the roots. Thus, salt damage often manifests as drought, especially under conditions of low atmospheric relative humidity. As transpiration increases, salt damage becomes increasingly severe.

[0004] Currently, soil salinity is often addressed using the following methods: Measure 1: Reduce fertilizer use and apply fertilizer rationally. Chemical fertilizers are a major source of soil salinization. By reducing fertilizer use and applying it rationally, soil salinization can be prevented at its source. Reducing use does not mean not using fertilizers at all, but rather applying them scientifically and rationally. Fertilizer application should be based on the results of soil nutrient testing in greenhouses and the nutrient requirements of different crops, adhering to the principle of balanced fertilization and supplementing deficiencies. Measure 2: Deep tillage and straw return to the field. Severely saline soil layers often exhibit compaction and poor aeration. In actual production, deep tillage can break up the soil structure, turning the topsoil with high total salt content to the bottom layer, reducing the degree of soil salinization. Applying 4000 kg of organic-rich farmyard manure per acre each time crop rotation can increase soil organic matter content and improve soil physical and chemical properties. When crop straw is used in greenhouse soil, it can absorb and utilize mineral elements in the soil during decomposition, while also increasing soil organic matter and improving soil aeration. Measure 3: Supplement with microbial fertilizer. Bio-fertilizers are rich in beneficial soil bacteria. Besides preventing soil-borne diseases through "bacterial inhibition," the beneficial bacteria in bio-fertilizers also play a role in nitrogen fixation, phosphorus solubilization, and potassium solubilization. This improves fertile soil and reduces salt damage. Bio-fertilizers can be applied in various ways, such as broadcasting, hole application, and fertigation. Measure 4: Add salt using water pressure. This is an effective and low-cost measure to address soil salinity. As the saying goes, "salt goes with water." Therefore, high concentrations of salt ions in the topsoil can be "carried away" through capillary action in the soil via flood irrigation. It is recommended to do this after vegetables are harvested and simultaneously with the high-temperature greenhouse, i.e., first till the ground, then seal the greenhouse for at least half a month. Alternatively, remove the greenhouse film during summer greenhouse renovations to allow frequent rainwater to flush away the salt in the soil. In summary, to reduce the adverse effects of soil salinization on crop growth, several measures should be taken, including: improving soil structure, irrigation management, and reducing salt residue; removing excess salt from the soil by selecting appropriate irrigation methods and managing soil salinity; increasing soil organic matter by adding organic matter, such as humus, to enhance soil biological activity and promote salt absorption and leaching; changing irrigation methods to reduce salt accumulation and increase soil moisture content; appropriate deep plowing to break up soil layers, improve soil aeration, and promote salt absorption and leaching; and increasing crop salt tolerance by selecting crops with higher salt tolerance to reduce the impact of salt on soil and crops. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a tiered salt removal and fixation method for improving saline-alkali land using multi-source sludge. The method utilizes a three-layer salt removal structure to create different void structures where different organic matter and soil are mixed. Combined with a permeable salt removal side chamber device, it can improve salt removal capacity without losing nutrients from compost products.

[0006] The first objective of this invention is to provide a method for cascaded salt drainage and fixation, comprising a salt drainage and fixation structure for saline-alkali land and an infiltration salt drainage side chamber device. The salt drainage and fixation structure for saline-alkali land includes a three-layer soil salt drainage structure from top to bottom: a surface soil salt drainage structure, a middle soil salt drainage structure, and a bottom soil salt drainage structure. The infiltration salt drainage side chamber device is disposed on the side of the salt drainage and fixation structure for saline-alkali land and includes a rainwater receiving box and a salt drainage ball storage chamber, which are connected by a semi-permeable membrane. The salt drainage ball storage chamber is filled with sludge salt drainage balls.

[0007] The surface soil salt-removing structure is a mixture of saline-alkali soil S0, fertilizer fixation S1, and decomposed products S2 in a mass ratio of S0:S1:S2 of (7-8):1:(1-2).

[0008] The middle soil desalination structure is a mixture of soil S0 from saline-alkali plots, fertilizer fixation material S1, and decomposed products S2 in a mass ratio of S0:S1:S2 of (6-6.5):1:(2.5-3).

[0009] The underlying soil salt-removing structure is a mixture of soil S0 and decomposed product S2 in a mass ratio of S0:S2 of (3-4):(6-7).

[0010] In one embodiment of the present invention, the fertilizer immobilization S1 is a mixture of dehydrated water supply sludge and fertilizer; further, the fertilizer is preferably a fertilizer containing one or more of nitrogen, phosphorus and potassium elements, and can be a single-element fertilizer or a compound fertilizer, or an inorganic fertilizer or an organic fertilizer.

[0011] In one embodiment of the present invention, the fertilizer includes one or more of nitrogen fertilizer, phosphate fertilizer, and potassium fertilizer, wherein the nitrogen fertilizer includes one or more of ammonium bicarbonate, urea, ammonium nitrate, ammonia, ammonium chloride, and ammonium sulfate; the phosphate fertilizer includes one or more of calcium phosphate and calcium magnesium phosphate; and the potassium fertilizer includes any one or more of potassium nitrate, potassium dihydrogen phosphate, potassium sulfate, and potassium chloride.

[0012] In one embodiment of the present invention, the water supply sludge is derived from the residues (particles, colloids and some soluble substances) generated during the raw water purification process of urban water supply plants, and can be any one or more of the sludge discharged from sedimentation tanks, sludge discharged from filter backwashing, and sludge discharged from clarifiers.

[0013] In one embodiment of the present invention, the mass ratio of fertilizer to water supply sludge (dry weight) in the fertilizer immobilization material S1 is 1:8-10.

[0014] In one embodiment of the present invention, the composted product S2 is a sludge composted product with a carbon-nitrogen ratio of (15-35):1, a salt content of less than 0.5% by mass, a humic acid / fulvic acid ratio of 0.2-0.6, and an organic matter content (based on dried basis) of ≥35%.

[0015] In one embodiment of the present invention, the composted product S2 is obtained by aerobic composting of high organic matter multi-source sludge (organic matter content of 25%-80%).

[0016] In one embodiment of the present invention, the high-organic-matter multi-source sludge includes municipal sludge, ditch sludge, and dredged sediment, etc.

[0017] In one embodiment of the present invention, the soil depth of the surface soil salt drainage structure is 20-30cm; the soil depth of the middle soil salt drainage structure is 40-50cm; and the soil depth of the bottom soil salt drainage structure is 50-70cm.

[0018] In one embodiment of the present invention, the sludge desalination ball is made of a hollow spherical frame of polytetrafluoroethylene material, wherein a semi-permeable membrane permeation window is installed in the hollow part for discharging weakly acidic substances that permeate from the semi-fermented sludge products.

[0019] In one embodiment of the present invention, the semi-permeable membrane is a mixed cellulose ester microporous filter membrane, a polypropylene microporous filter membrane (PP filter membrane), which has low water permeability and prevents rainwater from quickly seeping into the salt-absorbing ball storage chamber.

[0020] In one embodiment of the present invention, the rainwater receiving box collects natural rainwater, which slowly seeps through a semi-permeable membrane into the salt drainage ball storage chamber. After passing through the sludge salt drainage ball, the rainwater is discharged into the soil through the salt drainage ball storage chamber. The salt drainage ball storage chamber is sealed except for its connection to the soil and one side, which is connected to the rainwater receiving box. Preferably, the salt drainage ball storage chamber is located within the soil.

[0021] In one embodiment of the present invention, the sludge desalination ball contains high-organic-matter multi-source sludge (organic matter content of 25%-80%) obtained through anaerobic digestion; furthermore, the mesophilic anaerobic digestion temperature is maintained at 35℃±2℃, the residence time is 5-7 days, the organic matter decomposition rate reaches 10%-15%, and then it is dehydrated and loaded into the ball.

[0022] In one embodiment of the present invention, a first bearing is connected to the outer surface of the salt drainage ball storage chamber, and a rotating shaft is connected to the first bearing, extending into the interior of the salt drainage ball storage chamber. A connecting rod is connected to the outer surface of the rotating shaft, and a connecting groove is provided in the connecting groove. A spring connected to the inner wall of the connecting rod is provided in the connecting groove, and a silicone block is connected to the end of the spring away from the rotating shaft. A belt is connected to the rotating shaft, and a clearance groove is provided in the rainwater collection box. A drive mechanism is connected to the rainwater collection box, and the belt passes through the clearance groove and is connected to the drive mechanism. A critical indicator line is provided on the inner wall of the salt drainage ball storage chamber, and a support rod is connected to the bottom of the perforated plate. The bottom of the support rod is connected to the inner wall of the salt drainage ball storage chamber.

[0023] In one embodiment of the present invention, the driving mechanism includes a second bearing connected to the outer surface of the rainwater collection box. The second bearing is connected to a drive shaft extending into the interior of the rainwater collection box. Multiple blades are arranged in a circumferential array on the outer surface of the drive shaft. The drive shaft is connected to a belt. A baffle is fixedly connected to the inner wall of the rainwater collection box. The baffle is inclined, with the end of the baffle near the salt drainage ball storage chamber being lower than the end away from the salt drainage ball storage chamber. A through groove is formed at the end of the baffle near the salt drainage ball storage chamber, located on one side directly above the blades.

[0024] The present invention also includes a permeation desalination side chamber device, which includes a rainwater receiving tank and a desalination ball storage chamber, which are connected by a semi-permeable membrane. The desalination ball storage chamber is filled with sludge desalination balls.

[0025] In one embodiment of a permeable salt drainage side chamber device, the semi-permeable membrane is a mixed cellulose ester microporous filter membrane, a polypropylene microporous filter membrane (PP filter membrane), which has low water permeability, preventing rainwater from quickly seeping into the salt drainage ball storage chamber.

[0026] In one embodiment of the present invention, the sludge desalination ball contains high-organic-matter multi-source sludge (organic matter content of 25%-80%) obtained through anaerobic digestion; furthermore, the anaerobic digestion temperature is maintained at 35℃±2℃, the residence time is 5-7 days, the organic matter decomposition rate reaches 10%-15%, and then it is dehydrated and loaded into the ball.

[0027] In one embodiment, a permeation and desalination side chamber device includes a first bearing connected to the outer surface of the desalination ball storage chamber. The first bearing is connected to a rotating shaft extending into the interior of the desalination ball storage chamber. A connecting rod is connected to the outer surface of the rotating shaft. The connecting rod has a connecting groove, and a spring connected to the inner wall of the connecting rod is disposed within the connecting groove. A silicone block is connected to the end of the spring furthest from the rotating shaft. A belt is connected to the rotating shaft. A rainwater collection box has a void-avoiding groove and is connected to a driving mechanism. The belt passes through the void-avoiding groove and is connected to the driving mechanism. A critical indicator line is provided on the inner wall of the desalination ball storage chamber. A support rod is connected to the bottom of the perforated plate, and the bottom of the support rod is connected to the inner wall of the desalination ball storage chamber.

[0028] In one embodiment, a permeation and desalination side chamber device includes a driving mechanism comprising a second bearing connected to the outer surface of a rainwater collection tank. The second bearing is connected to a drive shaft extending into the interior of the rainwater collection tank. Multiple blades are arranged in a circumferential array on the outer surface of the drive shaft. The drive shaft is connected to a belt. A baffle is fixedly connected to the inner wall of the rainwater collection tank. The baffle is inclined, with the end of the baffle near the desalination ball storage chamber being lower than the end away from the desalination ball storage chamber. A through groove is provided at the end of the baffle near the desalination ball storage chamber, and the through groove is located on one side directly above the blades.

[0029] A permeation desalination side chamber device, in one embodiment, wherein the sludge desalination ball is made of polytetrafluoroethylene material with a hollow spherical frame, wherein a semi-permeable membrane permeation window is installed in the hollow part for discharging weakly acidic substances permeating from the semi-fermented sludge products.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] The reason why saline-alkali land is difficult to transform is that all the sea salt in saline-alkali land is trapped in the soil. The soil compacted by sea salt has very poor water permeability. Sodium chloride, calcium chloride, calcium carbonate, and magnesium salts are bound together and are difficult to dissolve. As a result, it is difficult to dissolve the salt in the soil by means of rainwater, and the rainwater is difficult to infiltrate, which further prevents the salt from being washed away.

[0032] (1) This invention utilizes the mixture of organic matter and soil to support the soil's pore structure, significantly increasing the soil's capillary porosity and non-capillary porosity. In addition, organic matter produces trace amounts of acid during degradation and stabilization. These trace amounts of acid dissolve the salt deposits in saline-alkali soil, making the salt structure loose. Sodium chloride dissolves in water, and water seeps through the soil's pores, thereby improving the soil's salt removal capacity.

[0033] (2) The present invention constructs a three-layer salt drainage structure, forming a mixed soil layer of different organic matter and soil. The upper layer has small pores, the middle layer has medium pores, and the lower layer has the largest pores. The organic matter itself has a very strong cation exchange rate and can store salt. With the process of rainwater scouring, the upper layer salt can seep downwards, while the lower layer salt cannot reach upwards, thereby achieving the purpose of continuously draining salt downwards and draining salt from saline-alkali land.

[0034] (3) This invention utilizes compost products as a component of the mixed soil, which can effectively reduce the compaction of saline-alkali land, reduce bulk density, and increase porosity, thereby improving water permeability, air permeability, and salt removal capacity. However, the increased water permeability can lead to leaching and loss of nitrogen, phosphorus, and potassium elements in the compost products during irrigation and salt removal. To address this, this invention adds water supply sludge to the soil. Water supply sludge contains a large amount of iron and aluminum salts, which have a strong adsorption and fixation capacity for nitrogen and organic matter. In this way, the nutrients in the compost products can be fixed by the water supply sludge and prevented from being washed away by the irrigation water. The method of this invention does not cause secondary pollution and can be widely used. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a front view of one embodiment of a method for cascade salt removal and fixation according to the present invention;

[0037] Figure 2 This is a perspective view of one embodiment of a method for step-by-step salt removal and fixation according to the present invention;

[0038] Figure 3 This is a top view of one embodiment of a method for step-by-step salt removal and fixation according to the present invention;

[0039] Figure 4 A perspective view of a baffle in one embodiment of a method for cascaded salt removal and fixation according to the present invention;

[0040] Figure 5 A perspective view of a rainwater collection box according to one embodiment of a cascade salt drainage and salt retention method of the present invention;

[0041] Figure 6 This is a perspective view of a salt-draining ball storage chamber, representing one embodiment of a step-by-step salt drainage and consolidation method according to the present invention.

[0042] Figure 7This is a cross-sectional view of a salt-draining ball storage chamber, representing one embodiment of a step-by-step salt drainage and consolidation method according to the present invention.

[0043] Figure 8 for Figure 7 Enlarged view of section A in the cross-sectional view of the middle salt ball storage room;

[0044] Figure 9 This is a schematic diagram showing the connection between the drive mechanism, belt, and rotating shaft in one embodiment of a method for cascaded salt removal and fixation according to the present invention.

[0045] Figure 10 This is a cross-sectional view of one embodiment of a method for step-by-step salt removal and fixation according to the present invention;

[0046] Figure 11 A schematic diagram of one implementation method of sludge desalination balls;

[0047] Among them, 1—rainwater receiving box, 2—salt discharge ball storage chamber, 3—discharge trough, 4—support rod, 5—perforated plate, 6—sludge salt discharge ball, 7—critical indicator line, 8—rotating shaft, 9—first bearing, 10—connecting rod, 11—connecting groove, 12—spring, 13—silicone block, 14—semi-permeable membrane, 15—baffle, 16—through groove, 17—drive shaft, 18—, 19—water impact blade, 20—belt, 21—avoiding groove. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] Soil salinity testing: determined according to LY / T1251-199 standard.

[0050] Example 1: A permeation salt removal side chamber device

[0051] A schematic diagram of one embodiment of the permeation salt removal side chamber device of the present invention is shown below. Figures 1-10As shown, the infiltration desalination side chamber device is located on one or both sides of the desalination and salt fixation structure of the saline-alkali land. The desalination and salt fixation structure of the saline-alkali land includes a three-layer soil desalination structure from top to bottom: a surface soil desalination structure, a middle soil desalination structure, and a bottom soil desalination structure. The surface soil desalination structure is a mixture of saline-alkali land soil S0, fertilizer fixation material S1, and decomposed product S2 in a mass ratio of S0:S1:S2 of (7-8):1:(1-2). The middle soil desalination structure is a mixture of saline-alkali land soil S0, fertilizer fixation material S1, and decomposed product S2 in a mass ratio of S0:S1:S2 of (6-6.5):1:(2.5-3). The bottom soil desalination structure is a mixture of saline-alkali land soil S0 and decomposed product S2 in a mass ratio of S0:S2 of (3-4):(6-7).

[0052] The permeation desalination side chamber device includes a rainwater receiving tank 1 and a desalination ball storage chamber 2, which are connected by a semi-permeable membrane 14. The desalination ball storage chamber is filled with sludge desalination balls 6. 3. A first bearing 9 is connected to the outer surface of the desalination ball storage chamber 2. The first bearing 9 is connected to a rotating shaft 8 that penetrates into the interior of the desalination ball storage chamber 2. A connecting rod 10 is connected to the outer surface of the rotating shaft 8. The connecting rod 10 has a connecting groove 11, and a connecting groove 11 is provided in the connecting rod 10. A spring 12 is connected to the wall, and a silicone block 13 is connected to the end of the spring 12 away from the rotating shaft 8. A belt 20 is connected to the rotating shaft 8. The rainwater receiving box 1 has a void groove 21. The rainwater receiving box 1 is connected to a drive mechanism. The belt 20 passes through the void groove 21 and is connected to the drive mechanism. A critical indicator line 7 is provided on the inner wall of the salt draining ball storage chamber 2. A support rod 4 is connected to the bottom of the hollow plate 5. The bottom of the support rod 4 is connected to the inner wall of the salt draining ball storage chamber 2.

[0053] The drive mechanism includes a second bearing 18 connected to the outer surface of the rainwater collection box 1. The second bearing 18 is connected to a drive shaft 17 that extends into the interior of the rainwater collection box 1. Multiple blades 19 are arranged in a circular array on the outer surface of the drive shaft 17. The drive shaft 17 is connected to a belt 20. A baffle 15 is fixedly connected to the inner wall of the rainwater collection box 1. The baffle 15 is inclined. The height of the end of the baffle 15 near the salt ball storage chamber 2 is lower than that of the end away from the salt ball storage chamber 2. A through groove 16 is opened at the end of the baffle 15 near the salt ball storage chamber 2. The through groove 16 is located on the side directly above the blades 19.

[0054] The sludge desalination ball 6 is made of polytetrafluoroethylene (PTFE) material with a spherical frame containing a semi-permeable membrane permeation window for discharging weakly acidic substances permeating from the semi-fermented sludge products. The ball contains the products obtained from the anaerobic digestion of high-organic-matter multi-source sludge (organic matter content of 25%-80%). Furthermore, the mesophilic anaerobic digestion temperature is maintained at 35℃±2℃, the residence time is 5-7 days, and the organic matter decomposition rate reaches 10%-15%. After that, it is dehydrated and loaded into the ball.

[0055] In this embodiment, during periods of heavy rainfall, rainwater falls onto the top of the rainwater collection box 1 and slides down the upper surface of the baffle 15. Then, it is concentrated and discharged downwards into the bottom of the rainwater collection box 1 through the channel 16. By setting the baffle 15 and the channel 16 to increase the water pressure, the water concentrated and discharged downwards into the bottom of the rainwater collection box 1 impacts the blades 19, causing the drive mechanism to start operating. During operation, the blades 19 drive the drive shaft 17 to rotate counterclockwise, causing the drive shaft 17 to drive the rotating shaft 8 to rotate through the belt 20. Then, the connecting rod 10, spring 12, and silicone block 13 are driven to rotate around the rotating shaft 8. During the rotation, the spring 12 extends and pushes the silicone block 13 to move inside the connecting groove 11, so that the silicone block 13 taps the surface of the semi-permeable membrane 14 during the rotation, causing the sludge salt removal ball 6 that has absorbed water and adhered to the surface of the semi-permeable membrane 14 to fall off, avoiding the sludge salt removal ball 6 that has absorbed water from adhering to the surface of the semi-permeable membrane 14 and causing blockage. This allows rainwater to pass smoothly through the semi-permeable membrane 14 and slowly seep into the salt removal ball storage chamber 2. In order to avoid the sharp corners of the silicone block 13 contacting the semi-permeable membrane 14 and causing it to break, the end of the silicone block 13 that taps the semi-permeable membrane 14 is set to be hemispherical. The placement height of the sludge salt removal ball 6 in the salt removal ball storage chamber 2 shall not be higher than the height of the critical indicator line 7, so as to avoid interference and collision between the sludge salt removal ball 6 and the rotating shaft 8, connecting rod 10, spring 12, and silicone block 13 during the rotation.

[0056] The present invention supports the hollow plate 5 and the sludge salt discharge ball 6 by setting a support rod 4, so as to prevent the sludge salt discharge ball 6 from accumulating on the top of the discharge trough 3 and causing it to be discharged poorly.

[0057] Example 2: A method for step-by-step salt removal and fixation

[0058] (1) Preparation of multi-source sludge derivatives S1 and S2

[0059] Preparation of fertilizer immobilization S1: After dewatering and compressing the water supply sludge, potassium dihydrogen phosphate fertilizer is added and mixed thoroughly to form fertilizer immobilization S1 for later use. The mass ratio of fertilizer to water supply sludge (dry weight) is 1:8.

[0060] Preparation of composted product S2: High organic matter multi-source sludge (organic matter content of 40%) is aerobically composted to form high organic matter multi-source sludge composted product S2. The carbon-nitrogen ratio of the composted product is 20:1, the salt content of the composted product is <0.5% by mass, the humic acid / fulvic acid ratio is 0.4, and the organic matter content (based on dry basis) is 53%.

[0061] (2) Construct a tiered salt drainage and salt-fixing structure

[0062] The tiered salt drainage and fixation structure includes a salt drainage and fixation structure for saline-alkali land and an infiltration salt drainage side chamber device. The salt drainage and fixation structure comprises a three-layer soil salt drainage structure from top to bottom: a surface soil salt drainage structure, a middle soil salt drainage structure, and a bottom soil salt drainage structure, with depths of 20cm, 40cm, and 55cm respectively. In Example 1, the infiltration salt drainage side chamber device is located on both sides of the salt drainage and fixation structure. The surface soil… The first layer of soil has a salt-removing structure consisting of a mixture of soil S0 from saline-alkali land, fertilizer fixation material S1, and decomposed products S2 in a mass ratio of S0:S1:S2 of 7:1:2; the second layer of soil has a salt-removing structure consisting of a mixture of soil S0 from saline-alkali land, fertilizer fixation material S1, and decomposed products S2 in a mass ratio of S0:S1:S2 of 6.5:1:3; and the third layer of soil has a salt-removing structure consisting of a mixture of soil S0 from saline-alkali land and decomposed products S2 in a mass ratio of S0:S2 of 4:6.

[0063] (3) Salt discharge test in saline-alkali land

[0064] The device of Example 1 was placed in a saline-alkali land with high soil salinity (1.5%) near the sea. The small balls of the salt-discharging ball contained high organic matter multi-source sludge (organic matter content of 50%), which was dehydrated after anaerobic fermentation at a temperature maintained at 35℃±2℃ for 6 days.

[0065] After 20 days of treatment with the device of this invention, the soil salinity can be reduced to 0.06%, and the topsoil can be maintained within a dynamic range of 0.06% ± 0.047%. There may be occasional instances where the salinity exceeds the standard, but this does not affect crop growth and can be used for planting most plants.

[0066] Example 3: A method for step-by-step salt removal and fixation

[0067] (1) Preparation of multi-source sludge derivatives S1 and S2

[0068] Preparation of fertilizer solids S1: After dewatering and compressing the water supply sludge, ammonium sulfate fertilizer is added and mixed thoroughly to form fertilizer solids S1 for later use. The mass ratio of fertilizer to water supply sludge (dry weight) is 1:10.

[0069] Preparation of composted product S2: High organic matter multi-source sludge (organic matter content of 50%) is aerobically composted to form high organic matter multi-source sludge composted product S2. The carbon-nitrogen ratio of the composted product is 30:1, the salt content of the composted product is <0.5% by mass, the humic acid / fulvic acid ratio is 0.5, and the organic matter content (based on dry basis) is >60%.

[0070] (2) Construct a tiered salt drainage and salt-fixing structure

[0071] The tiered salt drainage and fixation structure includes a salt drainage and fixation structure for saline-alkali land and an infiltration salt drainage side chamber device. The salt drainage and fixation structure comprises a three-layer soil salt drainage structure from top to bottom: a surface soil salt drainage structure, a middle soil salt drainage structure, and a bottom soil salt drainage structure, with depths of 30cm, 45cm, and 65cm respectively. In Example 1, the infiltration salt drainage side chamber device is located on both sides of the salt drainage and fixation structure. The surface soil… The first layer of soil has a salt-removing structure consisting of a mixture of soil S0 from saline-alkali land, fertilizer fixation material S1, and decomposed products S2 in a mass ratio of S0:S1:S2 of 8:1:2; the second layer of soil has a salt-removing structure consisting of a mixture of soil S0 from saline-alkali land, fertilizer fixation material S1, and decomposed products S2 in a mass ratio of S0:S1:S2 of 6:1:2.5; and the third layer of soil has a salt-removing structure consisting of a mixture of soil S0 from saline-alkali land and decomposed products S2 in a mass ratio of S0:S2 of 3:7.

[0072] (3) Salt discharge test in saline-alkali land

[0073] The device of Example 1 was placed in a saline-alkali land with high soil salinity (1.7%) near the sea. The small balls of the salt-discharging ball contained high organic matter multi-source sludge (organic matter content of 50%), which was dehydrated after anaerobic fermentation at a temperature maintained at 35℃±2℃ for 6 days.

[0074] After 30 days of treatment with the device of this invention, the soil salinity can be reduced to 0.08%, and the topsoil can be maintained within a dynamic range of 0.08% ± 0.024%, which is suitable for planting most plants.

[0075] By using the device and method of the present invention to treat saline-alkali land and change the soil structure, within the scope of the present invention, the initial soil salinity can be reduced from 0.5-2.2% to 0.05-0.1%, which truly solves the problem of salt drainage in saline-alkali land. It can structurally prevent salt from reaching the planting surface, thus enabling plant cultivation in saline-alkali land.

[0076] The above description of the embodiments is intended to enable those skilled in the art to understand and use the present invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments. Improvements and modifications made by those skilled in the art based on the principles of the present invention, without departing from the scope of the invention, should be within the protection scope of the present invention.

Claims

1. A method for step-by-step salt removal and fixation, characterized in that, The structure includes a salt drainage and salt fixation structure for saline-alkali land and an infiltration salt drainage side chamber device. The salt drainage and salt fixation structure for saline-alkali land includes a three-layer soil salt drainage structure from top to bottom: a surface soil salt drainage structure, a middle soil salt drainage structure, and a bottom soil salt drainage structure. The infiltration salt drainage side chamber device is located on the side of the salt drainage and salt fixation structure for saline-alkali land and includes a rainwater receiving box (1) and a salt drainage ball storage chamber (2), which are connected by a semi-permeable membrane (14). The salt drainage ball storage chamber (2) is filled with sludge salt drainage balls (6). The surface soil salt-removing structure is a mixture of saline-alkali soil S0, fertilizer fixation S1, and decomposed products S2 in a mass ratio of S0:S1:S2 of (7-8):1:(1-2). The middle soil desalination structure is a mixture of soil S0, fertilizer fixation S1, and decomposed products S2 in a mass ratio of S0:S1:S2 of (6-6.5):1:(2.5-3). The underlying soil salt drainage structure is a mixture of soil S0 and decomposed product S2 in a mass ratio of S0:S2 of (3-4):(6-7); The fertilizer immobilization material S1 is a mixture of dehydrated water supply sludge and fertilizer, and the mass ratio of fertilizer to water supply sludge in the fertilizer immobilization material S1 is 1:8-10. The composted product S2 is a sludge composted product with a carbon-to-nitrogen ratio of (15-35):1, a salt content of less than 0.5% by mass, a humic acid / fulvic acid ratio of 0.2-0.6, and an organic matter content of ≥35% by mass. The sludge desalination ball is made of polytetrafluoroethylene material with a hollow spherical frame, in which a semi-permeable membrane permeation window is installed.

2. The method for step-by-step salt removal and fixation according to claim 1, characterized in that, The surface soil salt drainage structure has a depth of 20-30cm; the middle soil salt drainage structure has a depth of 40-50cm; and the bottom soil salt drainage structure has a depth of 50-70cm.

3. The method for step-by-step salt removal and fixation according to claim 1, characterized in that, The outer surface of the salt draining ball storage chamber (2) is connected to a first bearing (9), the first bearing (9) is connected to a rotating shaft (8) that penetrates into the interior of the salt draining ball storage chamber (2), the outer surface of the rotating shaft (8) is connected to a connecting rod (10), the connecting rod (10) has a connecting groove (11), the connecting groove (11) is provided with a spring (12) connected to the inner wall of the connecting rod (10), the end of the spring (12) away from the rotating shaft (8) is connected to a silicone block (13), the rotating shaft (8) is connected to a belt (20), the rainwater receiving box (1) has a void groove (21), the rainwater receiving box (1) is connected to a drive mechanism, the belt (20) passes through the void groove (21) and is connected to the drive mechanism, the inner wall of the salt draining ball storage chamber (2) is provided with a critical indicator line (7), the bottom of the hollow plate (5) is connected to a support rod (4), the bottom of the support rod (4) is connected to the inner wall of the salt draining ball storage chamber (2).

4. The method for step-by-step salt removal and fixation according to claim 3, characterized in that, The drive mechanism includes a second bearing (18) connected to the outer surface of the rainwater receiving box (1). The second bearing (18) is connected to a drive shaft (17) that extends into the interior of the rainwater receiving box (1). Multiple blades (19) are distributed in a circular array on the outer surface of the drive shaft (17). The drive shaft (17) is connected to a belt (20). A baffle (15) is fixedly connected to the inner wall of the rainwater receiving box (1). The baffle (15) is inclined. The height of the end of the baffle (15) near the salt ball storage chamber (2) is lower than that of the end away from the salt ball storage chamber (2). A through groove (16) is opened at the end of the baffle (15) near the salt ball storage chamber (2). The through groove (16) is located on one side directly above the blades (19).

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