Comprehensive utilization system for saline-alkali soil and method for improving saline-alkali soil

Abstract

The invention provides a comprehensive utilization system for saline-alkali soil and a method for improving the saline-alkali soil. The system comprises a salt washing module, a salt removing module, a hydraulic control module and a water circulation module which are sequentially arranged in the water flow direction. Wherein the salt flushing module is configured to supply flushing water to the saline-alkali soil; the salt removal module is arranged at the downstream of the salt washing module and is vertically arranged in the edge soil of the saline-alkali land; the hydraulic control module is arranged at the downstream of the salt removal module; the water circulation module comprises a filtrate treatment system, the system further comprises a monitoring module, and the monitoring module is in signal connection with the salt washing module, the salt removal module and the water circulation module. According to the method, automation, recycling and sustainability of the saline-alkali soil improvement process are achieved, and remarkable economic and ecological benefits are achieved.

Description

Technical Field

[0001] This invention relates to the field of saline-alkali land remediation technology, and in particular to a comprehensive utilization system for saline-alkali land and a method for improving saline-alkali land. Background Technology

[0002] As one of the most important reserve arable land resources in my country, the comprehensive management and efficient utilization of saline-alkali land is a key way to implement the national strategy of "storing grain in the land and storing grain in technology", which is of great significance to ensuring national food security and promoting sustainable agricultural development.

[0003] Currently, comprehensive management technologies for saline-alkali land can be mainly divided into three categories: physical, chemical, and biological, as well as their integrated technologies.

[0004] Physical measures typically include leaching, irrigation and drainage, deep tillage, and land shaping. Among these, leaching control technology is one of the most widely used. Its principle is to use irrigation water to leach surface salts to deeper layers of the soil, which are then drained through a drainage system. While this method has the advantages of being quick and relatively simple to operate, its core bottleneck lies in the consumption of large amounts of freshwater resources. In many saline-alkali land areas in my country, freshwater resources are already scarce, which severely limits the large-scale application of this technology and poses a risk of causing secondary salinization due to rising groundwater levels.

[0005] Chemical measures primarily involve adding chemicals such as gypsum, sulfur, organic acids, and polymeric amendments to the soil. These chemicals reduce soil alkalinity (pH) and improve soil structure through ion exchange and neutralization reactions, thereby indirectly reducing salt hazards. However, these measures often suffer from drawbacks such as limited effectiveness and short duration of action. Furthermore, long-term, large-scale use may lead to soil compaction or secondary pollution, posing a potential threat to environmental safety.

[0006] Biological measures mainly include adjusting crop planting structure (such as planting salt-tolerant crops and halophytes), agroforestry (such as intercropping salt-tolerant trees with salt-tolerant pasture), and phytoremediation (such as planting plants with salt-accumulating capabilities, such as Suaeda salsa and reeds). While environmentally friendly, these methods generally suffer from slow results and long cycles. Furthermore, their effectiveness is greatly influenced by climate and soil conditions, and the related technical systems are still immature, making it difficult to meet the urgent need for rapid improvement of saline-alkali land to ensure food production.

[0007] In view of this, the present invention is proposed. Summary of the Invention

[0008] The purpose of this invention is to provide a comprehensive utilization system for saline-alkali land, which solves at least one of the problems mentioned in the background art. The system of this invention can remove salt at any time, taking into account factors such as crop planting time and soil salinity, and can achieve efficient utilization of water resources.

[0009] The first aspect of the present invention provides a comprehensive utilization system for saline-alkali land, comprising: a salt flushing module, a salt removal module, a hydraulic control module, and a water circulation module arranged sequentially along the water flow direction; The salt flushing module is configured to supply flushing water to the saline-alkali soil. The salt removal module is located downstream of the salt flushing module and is vertically installed in the soil at the edge of the saline-alkali land. The hydraulic control module is located downstream of the salt removal module and is used to collect the filtrate and form a head difference that drives the water flow direction. The water circulation module includes a filtrate treatment system for receiving and treating the filtrate collected by the hydraulic control module, and returning the treated water to the saline flushing module. The system also includes a monitoring module, which is connected to the salt flushing module, the salt removal module, and the water circulation module via signals.

[0010] According to some embodiments, the salt flushing module includes a freshwater tank and a drip irrigation device; preferably, the freshwater source of the freshwater tank includes one or more of rainwater collection, circulating water from the water circulation module, and externally supplemented freshwater; preferably, the drip irrigation device is evenly distributed in the saline-alkali land at intervals of 40-60 cm.

[0011] According to some embodiments, the freshwater in the freshwater tank has a pH value of 5.5-8.5 and an electrical conductivity of less than 0.5 mS / cm.

[0012] According to some embodiments, the salt removal module includes a block formed by compressing a salt adsorption material, the block being wrapped and fixed by a water-permeable non-woven fabric; preferably, the salt adsorption material is selected from one or more of biochar, zeolite, vermiculite, bentonite, woody peat, and cellulose fiber-based adsorbents.

[0013] According to some embodiments, the salt removal module is configured as follows: a placement trench with a depth of 2-3 m and a width of 1-2 m is dug at the edge of the saline-alkali land, and the blocks are arranged sequentially in the trench, with the placement depth of the blocks being 2-3 m or 0.5-0.8 m deeper than the topsoil layer; preferably, the surface of the placement trench is covered with a waterproof board.

[0014] According to some embodiments, the hydraulic control module includes a filtrate collection well and a deep well submersible pump disposed within the filtrate collection well; preferably, the filtrate collection well is constructed of permeable material, and the bottom of the filtrate collection well is 0.5-1 m deeper than the bottom of the salinity removal module; preferably, the deep well submersible pump is used to pump out the filtrate in the filtrate collection well so that the water level in the filtrate collection well is lower than the water level of the surrounding groundwater, thereby creating a head difference before and after the salinity removal module.

[0015] According to some embodiments, the filtrate treatment system treats the filtrate collected by the hydraulic control module to a pH value of 5.5-8.5 and a conductivity of less than 0.5 mS / cm before returning it to the freshwater tank of the salinity flushing module.

[0016] According to some embodiments, the monitoring module is embedded within the salt flushing module, the salt removal module, and the water circulation module; preferably, the monitoring module includes: a first sensor group disposed in the salt flushing module for monitoring the water quality of the freshwater pool and the salt content in the soil; a second sensor group disposed in the salt removal module for monitoring the salt adsorption saturation of the adsorbent material block, and issuing an alarm notification when the salt content reaches 80% of the adsorption threshold of the adsorbent material; and a third sensor group disposed in the water circulation module for monitoring the water quality before and after filtrate treatment.

[0017] A second aspect of the present invention provides a method for improving saline-alkali land using the above-described system, comprising the following steps: Before the start of the planting season or during the crop growing season, the salt flushing module is activated to inject flushing water into the soil; Salt flows into the salt removal module with the water flow, where the salt is adsorbed and removed; The hydraulic control module collects the treated filtrate and maintains the head difference by pumping water out of the water, thereby driving the water flow in a directional manner. The collected filtrate enters the water circulation module, is treated, and then reused in the salt rinsing module; The monitoring module monitors the parameters of each node in the system in real time and controls the operation and shutdown of the system according to preset thresholds.

[0018] In some embodiments, when the monitoring module detects that the soil salinity content has reached a preset target, it controls the salt flushing module to stop working; and / or, when the salt adsorption saturation of the adsorbent material in the salt removal module reaches 80% of its adsorption threshold, it sends a signal to replace the adsorbent material.

[0019] The present invention has at least the following beneficial effects: 1. Saline-alkali land is mainly located in arid and semi-arid regions and coastal areas where freshwater is scarce. The system and method of this invention can realize the recycling of freshwater resources and improve the efficiency of water resource utilization. 2. The system of the present invention has the advantages of simple construction and operation, low cost, and can be used for a long time after construction; 3. The operation of the system of the present invention is not affected by factors such as crop growing season and climate, which greatly improves the efficiency of comprehensive utilization of saline-alkali land. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the comprehensive utilization system of saline-alkali land in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the salt rinsing module in an embodiment of the present invention; Figure 3 This is a schematic diagram of the salt removal module in an embodiment of the present invention; Figure 4 This is a schematic diagram of the hydraulic control module in an embodiment of the present invention. Detailed Implementation

[0022] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0023] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form includes the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0024] It should be noted that if the text uses terms such as "first" or "second", these terms are only used to distinguish similar objects and should not be interpreted as indicating or implying their relative importance, order of precedence, or implicitly indicating the number of technical features indicated. It should be understood that the data in the descriptions of "first" and "second" can be interchanged where appropriate.

[0025] Throughout the accompanying drawings, identical elements are represented by the same or similar reference numerals. Conventional structures or configurations may be omitted where they might cause confusion in understanding the invention. Furthermore, the shapes, dimensions, and positional relationships of the components in the drawings do not reflect actual size, scale, or actual positional relationships. Additionally, any reference symbols placed within parentheses in this invention should not be construed as limiting the scope of the invention.

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0027] Figure 1 This is a schematic diagram of the comprehensive utilization system of saline-alkali land in an embodiment of the present invention.

[0028] One aspect of the present invention provides a comprehensive utilization system for saline-alkali land, such as... Figure 1 As shown, an embodiment of the saline-alkali land comprehensive utilization system of the present invention includes a salt flushing module 1, a salt removal module 2, a hydraulic control module 3, and a water circulation module 4 arranged sequentially along the water flow direction. In addition, the system also integrates a monitoring module (not shown).

[0029] 1. Salt rinse module 1 This module is the system's starting point, responsible for supplying flushing water to the saline-alkali soil. In this embodiment, as... Figure 2 As shown, the salinity flushing module 1 includes a freshwater tank 11 (e.g., with a capacity of 50 cubic meters) and a drip irrigation system 12. The drip irrigation system 12 can deliver freshwater to the saline-alkali land at a certain flow rate and frequency through the flushing pipe 13.

[0030] Freshwater tank 11: Its freshwater source can be a mixture of rainwater harvesting, recycled water from water circulation module 4, and externally supplemented freshwater (such as river water or tap water). In some embodiments, the freshwater source in the freshwater tank mainly relies on rainwater harvesting and the recycling of water in the system, with external freshwater supplemented as needed when the water source is insufficient. By ensuring diversified water sources, the system's dependence on external freshwater resources is reduced.

[0031] Drip irrigation device 12: An embedded flushing pipe can be used, evenly distributed in the saline-alkali land at intervals of 40-60 cm, such as 45 cm, 50 cm, 54 cm, 58 cm, etc. In some embodiments, the drip irrigation device 12 can be connected to an automatic control system, which, according to the instructions of the monitoring module 5, delivers fresh water to the root zone twice a day at a flow rate of 1.5 liters per plant each time. The pH value of the fresh water is between 5.5 and 8.5, such as 5.8, 6.0, 6.5, 7.2, 7.8, 8.3, etc., and the electrical conductivity EC is controlled below 0.5 mS / cm, such as below 0.4 mS / cm, 0.2 mS / cm, 0.1 mS / cm, etc., to ensure that the flushing water itself does not introduce new salts. The pH value can be adjusted by adding a weak acid or a weak alkali.

[0032] 2. Salt Removal Module 2 like Figure 1 As shown, this module is located downstream of the salt flushing module 1, vertically positioned in the soil downstream of the edge of the saline-alkali land, and is used to adsorb and retain salts that migrate with the water flow. In this embodiment, as... Figure 3 As shown, the salt removal module 2 is composed of a block 21 formed by compressing salt adsorption material. The block 21 is wrapped and fixed with a water-permeable non-woven fabric, which ensures smooth water flow and prevents the compressed material from disintegrating when it comes into contact with water. In some embodiments, the block 21 can be a cube with a side length of 50-60 cm, which is convenient for installation and use and can achieve a good adsorption effect.

[0033] Adsorption Material: The salt adsorption material of block 21 is selected from one or more of biochar, zeolite, vermiculite, bentonite, woody peat, and cellulose fiber-based adsorbents. For example, it can be biochar, zeolite, a mixture of bentonite and cellulose fiber-based adsorbents, or a mixture of zeolite, vermiculite, and bentonite. Specifically, in one embodiment, it is a mixture of biochar and zeolite (mass ratio 1:1). Biochar has a rich porous structure, and zeolite has excellent ion exchange capacity; the synergistic effect of the two can efficiently adsorb Na. + Cl - Salt-equalized ions.

[0034] Installation method: A trench 22 is dug at the edge of the saline-alkali land, with a depth of 2-3 m (e.g., 2.2 m, 2.5 m, 2.8 m) and a width of 1-2 m (e.g., 1.3 m, 1.5 m, 1.7 m, 1.9 m). The blocks 21 (e.g., 32 blocks) are placed tightly in the trench 22, ensuring that the depth of the blocks is 0.5-0.8 m deeper than the topsoil layer (e.g., 0.6 m, 0.7 m, 0.75 m) to effectively intercept infiltrating salt. To prevent direct infiltration of surface runoff, a waterproof membrane 23 is placed on the surface of the trench.

[0035] 3. Hydraulic Control Module 3 This module is located downstream of the salt removal module 2 and is used to form a hydraulic gradient that drives the directional flow of water. It can be located outside the saline-alkali land to be treated area. In this embodiment, the hydraulic control module 3 includes a filtrate collection well 31 and a deep well submersible pump 32 installed in the well 31.

[0036] Filtrate collection well 31: One or more filtrate collection wells can be constructed in the area 1-1.5 m behind the hydraulic control module. The collection well 31 can be constructed using permeable materials, and its bottom is 0.5-1 m deeper than the bottom of the salt removal module, for example, 0.6 m, 0.8 m, 0.9 m, etc.

[0037] Deep well submersible pump 32: It is installed inside well 31 and its operation is controlled by monitoring module 5. When the whole system is running, the submersible pump 32 is turned on to ensure that the water level in well 31 is lower than the groundwater level, creating a head difference before and after the salt removal module 2, ensuring that the salt flushing water flows through the salt removal module 2 and flows into the filtrate collection well 31.

[0038] 4. Water circulation module 4 This module enables closed-loop management of water resources. Its core is the filtrate treatment system, which receives the filtrate from the hydraulic control module 3, treats it to meet the water quality standards of pH 5.5-8.5 and conductivity less than 0.5 mS / cm, and then returns it to the freshwater tank 11 of the salinity flushing module 1 through pipelines, thus realizing the recycling of water resources.

[0039] 5. Monitoring Module This module is the "brain" of the system, embedded in various modules, enabling intelligent monitoring of the entire process.

[0040] The first sensor group can be installed in the freshwater pool 11 to monitor the pH value and electrical conductivity (EC value) of the water in real time; at the same time, soil salinity sensors can be buried in the topsoil of saline-alkali plots to monitor changes in soil salinity.

[0041] The second sensor group can be embedded in the block 21 of the salt removal module 2. It indirectly reflects the salt adsorption saturation by monitoring the change in the internal conductivity of the block. When the saturation reaches 80% of the material adsorption threshold (determined through previous experiments), the monitoring center will issue an alarm (e.g., audible and visual) to prompt maintenance personnel to replace the adsorption material.

[0042] The third sensor group is installed on the inlet and outlet pipes of the water circulation module 4 to monitor the pH and EC values ​​before and after filtrate treatment, ensuring that the quality of the recycled water meets the standards.

[0043] Another aspect of the present invention provides a method for improving saline-alkali land using the above-described system, comprising the following steps: 1. System Start-up: Before the planting season or during the crop growing season, the monitoring module determines that the soil salinity exceeds the standard and automatically starts the drip irrigation equipment 12 of the salt flushing module 1 to inject low-salt fresh water into the soil for flushing. It is recommended that the saline-alkali land comprehensive utilization system of the present invention be operated before the start of the planting season. If it is operated during the crop growing season, the nutrients required by the crops should be replenished in time to ensure the normal growth of the crops.

[0044] 2. Salt Migration and Adsorption: Freshwater infiltration washes away salts from the soil. Driven by the head difference generated by the hydraulic control module 3, the saline water flow is horizontally transported to the salt removal module 2. The salts in the water flow are efficiently captured by the adsorption material in block 21, achieving desalination.

[0045] 3. Filtrate Collection and Drive: The desalinated filtrate continues to flow to the filtrate collection well 31 and is collected. The deep well submersible pump 32 automatically starts and stops according to the water level in the well to maintain the hydraulic drive of the system.

[0046] 4. Water recycling: The collected filtrate is pumped into the water recycling module 4 for treatment to remove salt until the water quality meets the standards, and then returned to the freshwater tank 11 for the next round of rinsing.

[0047] 5. Intelligent Monitoring and Control: The monitoring module provides real-time monitoring throughout the process. When the soil salinity sensor indicates that the soil salinity has dropped to a safe range for crop growth (e.g., ECe < 4 dS / m, as specified in Table A.1 of the "General Technology for Saline-Alkali Land Improvement Part 3: Biological Improvement" GB / T 42828.3-2023), the system automatically stops flushing. When the second sensor group alarms, the saturated adsorbent material block 21 is replaced manually in a timely manner to restore the system's efficient desalination capacity.

[0048] In summary, the basic concept of this invention is to construct a closed-loop saline-alkali land improvement system that integrates flushing, interception, collection, purification, and recycling. This system efficiently and continuously removes soil salinity through a combination of adsorption and hydraulic drive, while simultaneously achieving water resource recycling, thus overcoming the problems of high water consumption and the tendency to induce secondary salinization associated with traditional flushing methods.

[0049] This invention, through modular design, automates, optimizes, and sustains the process of improving saline-alkali land, resulting in significant economic and ecological benefits.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A comprehensive utilization system for saline-alkali land, characterized in that, It includes a salt flushing module, a salt removal module, a hydraulic control module, and a water circulation module arranged sequentially along the water flow direction; The salt flushing module is configured to supply flushing water to the saline-alkali soil. The salt removal module is located downstream of the salt flushing module and is vertically installed in the soil at the edge of the saline-alkali land. The hydraulic control module is located downstream of the salt removal module and is used to collect the filtrate and form a head difference that drives the water flow direction. The water circulation module includes a filtrate treatment system for receiving and treating the filtrate collected by the hydraulic control module, and returning the treated water to the saline flushing module. The system also includes a monitoring module, which is connected to the salt flushing module, the salt removal module, and the water circulation module via signals.

2. The system according to claim 1, characterized in that, The salt flushing module includes a freshwater tank and a drip irrigation system; Preferably, the freshwater source for the freshwater tank includes one or more of the following: rainwater collection, circulating water from the water circulation module, and externally supplemented freshwater. Preferably, the drip irrigation equipment is evenly distributed in the saline-alkali land at intervals of 40-60 cm.

3. The system according to claim 2, characterized in that, The freshwater in the freshwater tank has a pH value of 5.5-8.5 and an electrical conductivity of less than 0.5 mS / cm.

4. The system according to any one of claims 1-3, characterized in that, The salt removal module includes a block formed by compressing salt adsorption material, and the block is wrapped and fixed by a water-permeable non-woven fabric. Preferably, the salt adsorption material is selected from one or more of biochar, zeolite, vermiculite, bentonite, woody peat, and cellulose fiber-based adsorbents.

5. The system according to claim 4, characterized in that, The salt removal module is set up in the following way: a placement trench with a depth of 2-3 m and a width of 1-2 m is dug at the edge of the saline-alkali land, and the blocks are arranged in sequence in the trench, with the placement depth of the blocks being 2-3 m or 0.5-0.8 m deeper than the topsoil layer. Preferably, the surface of the placement trench is covered with a waterproof membrane.

6. The system according to any one of claims 1-5, characterized in that, The hydraulic control module includes a filtrate collection well and a deep well submersible pump installed in the filtrate collection well; Preferably, the filtrate collection well is constructed using a permeable material, and the bottom of the filtrate collection well is 0.5-1 m deeper than the bottom of the salt removal module; Preferably, the deep well submersible pump is used to pump out the filtrate in the filtrate collection well so that the water level in the filtrate collection well is lower than the water level of the surrounding groundwater, thereby creating a head difference before and after the salinity removal module.

7. The system according to any one of claims 1-6, characterized in that, The filtrate treatment system processes the filtrate collected by the hydraulic control module to a pH value of 5.5-8.5 and a conductivity of less than 0.5 mS / cm before returning it to the freshwater tank of the salinity flushing module.

8. The system according to any one of claims 1-7, characterized in that, The monitoring module is embedded in the salt flushing module, the salt removal module, and the water circulation module; Preferably, the monitoring module includes: The first sensor group installed in the salt flushing module is used to monitor the water quality of the freshwater pool and the salt content in the soil. The second sensor group installed in the salt removal module is used to monitor the salt adsorption saturation of the adsorption material block. When the salt content reaches 80% of the adsorption threshold of the adsorption material, an alarm notification is issued. The third sensor group, located in the water circulation module, is used to monitor the water quality before and after filtrate treatment.

9. A method for improving saline-alkali land using the system described in any one of claims 1-8, characterized in that, Includes the following steps: Before the start of the planting season or during the crop growing season, the salt flushing module is activated to inject flushing water into the soil; Salt flows into the salt removal module with the water flow, where the salt is adsorbed and removed; The hydraulic control module collects the treated filtrate and maintains the head difference by pumping water out of the water, thereby driving the water flow in a directional manner. The collected filtrate enters the water circulation module, is treated, and then reused in the salt rinsing module; The monitoring module monitors the parameters of each node in the system in real time and controls the operation and shutdown of the system according to preset thresholds.

10. The method according to claim 9, characterized in that, When the monitoring module detects that the soil salinity content has reached a preset target, it controls the salt flushing module to stop working; and / or, when it detects that the salt adsorption saturation of the adsorbent material in the salt removal module has reached 80% of its adsorption threshold, it sends a signal to replace the adsorbent material.

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