Desalting system and method

Abstract

The embodiment of the invention provides a desalting system and method, and belongs to the field of saline-alkali soil transformation. The desalting system comprises a leaching device used for containing salinized soil; the spraying device is used for spraying the salinized soil so as to flush salt in the salinized soil; the leaching device is used for spraying salinized soil, the leaching device is also used for filtering the sprayed salinized soil to obtain a salt-containing leaching solution, and the electrodialysis device is used for carrying out electrodialysis treatment on the salt-containing leaching solution to separate out fresh water and strong brine. The salt in the salinized soil can be thoroughly decomposed.

Description

Technical Field

[0001] The invention relates to the technical field of saline-alkali land transformation, and in particular to a desalination system and method. Background Art

[0002] Soil salinization is caused by the influence of salt and alkali substances to varying degrees, resulting in soil compaction, poor water permeability, and difficulty in the infiltration of salt and alkali. There are more than 100 countries in the world with different types of saline soils, and my country's saline soils account for about one-tenth of the world's total saline soil area. my country's saline soil area is huge and diverse, and the salinization problem is prominent, which has caused varying degrees of impact on agricultural production and the ecological environment. Saline soils are distributed in both the north and south of my country, mainly in the north and coastal areas.

[0003] Soil salinization breaks the balance of the plant growth environment. Higher salt concentrations increase the osmotic pressure of the soil solution, weakening the ability of plant roots to absorb water and nutrients. Some salt ions can cause plant cell damage, poisoning plants and limiting their growth. The number of soil organisms will also decrease and their activity will weaken. Soil salinization will reduce land productivity, water quality, and soil biodiversity. The ability of soil affected by salt to buffer and filter pollutants will decrease. Salinized soil reduces the ability of crops to absorb water and the effectiveness of trace elements, and may degrade soil structure.

[0004] The core of saline-alkali land management and soil salinization prevention and control is to optimize the regulation of soil water and salt according to the dynamic changes of soil salinity and the characteristics of environmental factors, remove or reduce soil salt, prevent salt accumulation, inhibit the harm of salt and alkali to plants, and reduce the adverse effects on the ecological environment.

[0005] At present, the main methods for desalination of large areas of salinized land are water improvement (such as irrigation, drainage, silt release, rice planting or anti-seepage, etc.), agricultural and chemical improvement technical measures (leveling the land, improving tillage, applying foreign soil, fertilization, sowing, crop rotation or intercropping, etc.) or biological improvement measures (planting salt-tolerant plants and forage, green manure, afforestation, etc.), chemical improvement measures (application of improvement substances, such as gypsum, phosphogypsum, calcium sulfite, etc.).

[0006] Among them, irrigation and salt removal or underground pipe salt removal measures in water conservancy improvement measures require the laying of water conservancy facilities and long-term periodic irrigation and drainage for salt removal in saline-alkali land, and the investment in engineering measures is relatively large. However, the existing irrigation and salt removal or underground pipe salt removal methods will cause salt return problems over time, resulting in the inability to completely desalinate the saline-alkali land.

[0007] Alternatively, agricultural and chemical measures can be combined to plant salt-tolerant plants or crops to apply amendments to reduce the mobility of salt ions and reduce their physiological damage to planted plants. However, this method will increase the risk of secondary pollution of salinized land by the added amendments, and the effect of chemical amendments is not sustainable, the treatment cycle is long, and the amount of manual maintenance is large. Summary of the invention

[0008] The purpose of the embodiments of the present invention is to provide a desalination system and method, which can partially or completely solve the technical problem of repeated salt return caused by the inability to completely decompose saline soil in the prior art.

[0009] In order to achieve the above-mentioned purpose, an embodiment of the present invention provides a desalination system, which includes: a leaching device for holding saline soil; a spraying device for spraying the saline soil to flush the salt in the saline soil; and an electrodialysis device, wherein the leaching device is also used to filter the saline soil after spraying to obtain a salt-containing leaching liquid, and the electrodialysis device is used to perform electrodialysis treatment on the salt-containing leaching liquid to separate fresh water and concentrated brine.

[0010] Optionally, the leaching device includes: a dump box for holding saline soil; a first filtering module for filtering the saline soil in the saline leaching liquid; and a second filtering module for secondary filtering the saline soil in the saline leaching liquid filtered by the first filtering module.

[0011] Optionally, a first filter net is provided between the dump box and the first filter module to prevent saline soil in the dump box from entering the first filter module; a second filter net is provided between the first filter module and the second filter module to prevent saline soil in the salt-containing filtrate filtered by the first filter module from entering the second filter module.

[0012] Optionally, the first filter module is filled with medium-coarse sand, and the second filter module is filled with gravel.

[0013] Optionally, the dump box is a U-shaped structure with a top opening size larger than a bottom size.

[0014] Optionally, the desalination system further comprises: a circulation device for recycling the separated fresh water to spray the saline soil.

[0015] Optionally, the desalination system further comprises: a solar energy device, which is used to supply power to the spraying device, the leaching device and the electrodialysis device.

[0016] Optionally, the leaching device is connected to the electrodialysis device via a detachable tube.

[0017] On the other hand, the present invention also provides a desalination method, which comprises: spraying saline soil to wash away the salt in the saline soil; filtering the sprayed saline soil to obtain a salt-containing leaching solution; and performing electrodialysis treatment on the salt-containing leaching solution to separate fresh water and concentrated brine.

[0018] Optionally, the desalination method includes: recycling the separated fresh water to spray the saline soil.

[0019] Through the above technical solution, the desalination system includes a leaching device for holding saline soil; a spraying device for spraying the saline soil to wash away the salt in the saline soil; and an electrodialysis device, and the electrodialysis device is used to perform electrodialysis treatment on the salt-containing leaching liquid to separate fresh water and concentrated brine. The technical solution of the present invention uses fresh water to leach the saline soil, thereby washing out the salt in the saline soil, and separating the washed salt into fresh water and concentrated brine through the electrodialysis device, thereby achieving the purpose of fully decomposing the salt in the saline soil. At the same time, the separated fresh water can also be used for reuse, and the separated concentrated brine can further extract industrial salt, thereby achieving the purpose of energy saving and environmental protection.

[0020] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0022] Figure 1 is a schematic diagram of a desalination system provided by a first embodiment of the present invention;

[0023] Figure 2 is a schematic structural diagram of a leaching device provided by a first embodiment of the present invention;

[0024] Figure 3 It is a partial structural schematic diagram of a leaching device provided by the first embodiment of the present invention;

[0025] Figure 4 is a top view of a dump box provided by a first embodiment of the present invention;

[0026] Figure 5 is a structural diagram of a desalination system provided by a first embodiment of the present invention;

[0027] Figure 6 It is a schematic diagram of a desalination system provided in the second embodiment of the present invention.

[0028] Description of Reference Numerals

[0029] 1 dump box 2 first filter module

[0030] 3 Second filter module 4 First filter

[0031] 5 Second filter 6 Removable tube

[0032] 6 filtration membrane 10 leaching device

[0033] 11 Spraying device 12 Electrodialysis device

[0034] 13 circulation device 14 solar energy device DETAILED DESCRIPTION

[0035] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0036] Figure 1 Schematic diagram of a desalination system provided by the first embodiment of the present invention. The desalination system comprises: a leaching device for holding saline soil; a spraying device for spraying the saline soil to wash away the salt in the saline soil; and an electrodialysis device, wherein the leaching device is also used to filter the saline soil after spraying to obtain a saline leaching liquid, and the electrodialysis device is used to perform electrodialysis treatment on the saline leaching liquid to separate fresh water and concentrated brine.

[0037] Specifically, the embodiment of the present invention excavates the saline soil in the saline-alkali land within a depth of 1-50 cm and places it in the leaching device 10, and uses fresh water to flush the saline soil in the leaching device 10 through the spraying device 11, so as to flush the salt in the saline soil to obtain soil that meets the saline-alkali land transformation standards (specific measurement and detection standards can be measured and tested by existing technical means), and the treated soil is backfilled to the original soil extraction position. Then the desalination system is moved to the next piece of land, and the next batch of saline soil to be treated is added to the leaching device, and the saline soil is cyclically treated according to the treatment requirements of the next stage. To ensure the flushing effect, the spraying device 11 can be arranged directly above the leaching device 10. Exemplarily, the spraying device 11 can be a plurality of nozzles arranged in parallel for spraying fresh water.

[0038] The present invention uses an integrated desalination system to concentrate the desalination treatment of saline soil in a certain area of ​​saline-alkali land. The skid-mounted desalination system can be quickly installed and put into use. After the treatment is completed, it can be loaded and transported to the next treatment site. The technical advantage of treating and transforming saline-alkali land wherever it is needed is achieved. In addition, the integrated desalination system can be installed and treated in blocks according to the requirements of saline-alkali land treatment, and different treatment scale modules can be combined according to the layout requirements, which has high flexibility.

[0039] The leaching device 10 is also used to filter the saline soil after spraying to obtain a saline leaching solution. Then, the saline leaching solution is subjected to electrodialysis treatment by the electrodialysis device 12 to separate the saline leaching solution into fresh water and concentrated brine. On-site desalinated water collection can be carried out using a temporary support pool or a fixed pool built on site, and concentrated brine can be collected using ton barrels. The separated fresh water can be recycled, and the concentrated brine can be used to extract industrial salt.

[0040] The electrodialysis device 12 can use anion and cation exchange membrane components with mature technology and commercial purchase as the medium for separating anions and cations in the salt components, ensuring that the desalination effect is stable and feasible. When the salt-containing leaching solution enters the small chamber in the electrodialysis device, under the action of the DC electric field, the ions in the solution migrate in a directional manner, with cations migrating to the cathode and anions migrating to the anode. Since the ion exchange membrane has selective permeability, the ion concentration of some small chambers is reduced and becomes a fresh water chamber, and the small chambers adjacent to the fresh water chamber become concentrated water chambers due to the enrichment of a large number of ions. Fresh water and concentrated water are obtained from the fresh water chamber and the concentrated water chamber, respectively, and the ions in the leached salt water are separated and concentrated, and the water is purified.

[0041] The embodiment of the present invention uses fresh water to leach the saline soil, thereby washing out the salt in the saline soil, and uses a leaching device to filter the saline soil after spraying to obtain a saline leaching liquid. The saline leaching liquid is then separated into fresh water and concentrated brine by an electrodialysis device, thereby achieving the purpose of fully decomposing the salt in the saline soil.

[0042] Furthermore, the leaching device includes: a dump box for holding saline soil; a first filtering module for filtering the saline soil in the saline leaching liquid; and a second filtering module for secondary filtering the saline soil in the saline leaching liquid filtered by the first filtering module.

[0043] Furthermore, a first filter net is arranged between the dump box and the first filter module to prevent the saline soil in the dump box from entering the first filter module; a second filter net is arranged between the first filter module and the second filter module to prevent the saline soil in the salt-containing leaching liquid filtered by the first filter module from entering the second filter module.

[0044] Specifically, Figure 2 It is a schematic diagram of the structure of the leaching device provided by the first embodiment of the present invention. Exemplarily, the leaching device 10 includes a dump box 1 for containing saline soil. After the saline soil is treated, the soil contained in the dump box can be backfilled into the original land. The bottom of the dump box 1 includes two layers of filter modules in sequence (which can be set according to actual needs), and the first filter module 2 is arranged at the bottom of the dump box 1. After the saline soil in the dump box 1 is sprayed and flushed by the spray device 11, the flushed liquid is filtered by the first filter module 2. The second filter module 3 is arranged below the first filter module, and is used for secondary filtering of the saline soil in the salt-containing leaching liquid filtered by the first filter module 2.

[0045] Since the salty leachate produced in the leached saline soil is corrosive, there are corresponding requirements for the material of the dump box. The preferred material of the dump box is Q345B steel, which has the characteristics of high strength, wear resistance, corrosion resistance, high temperature resistance, and low temperature resistance. If the dump box volume is large, the amount of saline soil treated each time is 20m 3 The above, the material of the dump box is preferably Q550 steel. Compared with Q345B material, Q550 steel has better impact resistance and is suitable for loading and unloading of large amounts of saline soil. The material itself has the characteristics of high strength, high toughness, wear resistance, and corrosion resistance. The dump box can also use a temporary dump truck as construction equipment.

[0046] In order to prevent the saline soil in the dump box 1 from entering the electrodialysis device 12 together with the salt-containing leaching liquid, a first filter screen 4 is provided between the dump box 1 and the first filter module 2 in the embodiment of the present invention. Figure 3 The first filter module and the second filter module, the first filter screen and the second filter screen provided in the first embodiment of the present invention are partially schematically shown in FIG. 2 Filament geotextile and 304 stainless steel mesh. Among them, 400g / m 2 The filament geotextile and 304 stainless steel mesh are filter meshes for saline soil, which prevent saline soil from entering the second filter module. In order to further prevent the saline soil in the salt-containing leaching solution filtered by the first filter module 2 from entering the second filter module 3, a second filter mesh 5 is also provided at the bottom of the first filter module 2. Preferably, the second filter mesh 5 is a 304 stainless steel mesh, which is a filter mesh for filtering sand, and prevents medium and coarse sand from entering the subsequent filter pipe during the filtering of the salt-containing leaching solution. The first filter mesh 4 is connected to the first filter module 2 by fastening bolts, and the second filter mesh 5 is connected to the second filter module 2 by fastening bolts.

[0047] The purpose of setting up the two-layer filter module and the filter screen is to ensure the purity of the salt-containing leaching liquid in the liquid entering the electrodialysis device, to prevent saline soil particles from entering the electrodialysis device and clogging the electrodialysis device, thereby reducing its service life.

[0048] Furthermore, the first filter module is filled with medium-coarse sand, and the second filter module is filled with gravel.

[0049] For example, the medium-coarse sand, gravel or pebbles serve as a channel for the infiltration of the salt-containing leachate and can prevent saline soil particles from entering the salt solution electrodialysis device. Preferably, gravel or pebbles with a diameter of 20-40 mm can be selected. Preferably, the dump box, the first filter screen 4 and the second filter screen 5 can be fixed by bolts (refer to Figure 3 The filter layer can be disassembled for cleaning after construction loss or clogging, and can be reinstalled for reuse.

[0050] Furthermore, the dump box is a U-shaped structure with a top opening size larger than a bottom size.

[0051] Specifically, refer to Figure 2 Side view of the middle dump box, the dump box is a U-shaped structure with a top opening size larger than the bottom size, and the bottom protrudes outward. Preferably, the leaching device for saline soil includes a dump box 1 with a hydraulic device on one side, and the bottom of the dump box 1 is a slow funnel-shaped steel plate with two sides inclined toward the middle. The size of the dump box 1 is the size of a conventional dump truck dump box, with a design size of 2.3m×5.9m or 3.15m×7.05m, and can also be customized according to the width of the dump box of the vehicle used on site. The height of the dump box should not exceed 1.5m, which is convenient for the infiltration of the spray liquid and avoids vehicle overloading.

[0052] Figure 4 The top view of the dump box, wherein the first filter screen 4 at the bottom of the dump box is a slit steel plate with a slit size of 1-2 mm. The structure of the dump box and the slit steel plate is conducive to discharging the salt-containing leaching liquid in the saline soil, thereby improving the efficiency of salt treatment of the saline soil.

[0053] The dump box 1 is an integral steel plate structure. The first filter screen is fixed by bolts. The medium-coarse sand and gravel pebbles are fixed in the first filter screen and the geotextile. After construction loss or clogging of the filter layer, it can be disassembled for cleaning and reinstalled for reuse. Figure 6 The funnel-shaped leachate drainage and filtration pipeline below the middle leaching device is a structure supported below the bottom of the slit of the dump box and is fastened to the leaching device 10 by bolts.

[0054] Furthermore, the leaching device is connected to the electrodialysis device via a detachable tube.

[0055] The leaching device 10 is connected to the electrodialysis device 12 through a detachable tube 6, and the pipeline can be cleaned regularly to prevent blockage. Preferably, a filter membrane 7 can be arranged between one end of the detachable tube 6 and the leaching device, and a filter membrane (not shown in the figure) can also be arranged between the other end of the detachable tube and the electrodialysis device. Among them, 0.05-0.15mm fine sand can also be arranged in the detachable tube 6 to filter the salt-containing leaching liquid multiple times to ensure the purity of the salt-containing leaching liquid entering the electrodialysis device.

[0056] The above technical scheme is to load the excavated saline soil into the dump box of the desalination equipment, fill and level it, and use a spray device to spray the saline soil. The salt substances in the saline soil are easily soluble in water and are transferred from the soil to the spray water. The spray water washes out the salt in the saline soil during the infiltration process, and is filtered through the medium-coarse sand and fine sand of different particle sizes filled in the pipeline and then gathered at the water inlet of the electrodialysis device.

[0057] Furthermore, the desalination system further comprises: a solar device 14, and the solar device 14 is used to supply power to the spray device 11, the leaching device 10 and the electrodialysis device 12. Preferably, Figure 5 It is a structural diagram of a desalination system provided in the first embodiment of the present invention.

[0058] The solar device is connected to the inverter and the battery pack, and the battery pack is used as the power supply for the electrodialysis equipment. The desalination system of the present invention uses solar power generation equipment to power the electrodialysis device and other electrical equipment on site, solving the construction problem in saline-alkali areas with remote geographical locations and harsh on-site conditions. The use of green energy to supply electricity to the entire system meets the national requirements for energy conservation, emission reduction and development of green advanced technologies.

[0059] In short, the present invention aims to solve the problems of small salt removal, long removal cycle, large infrastructure construction workload and continuous maintenance effect in the current restoration and management of saline-alkali land. The salt content is greatly reduced and removed by short-term and thorough desalination operations. And the mature, low-cost and easy-to-maintain electrodialysis technology principle is used to desalinate salt water. Using solar clean energy as the system energy supply is an environmentally friendly and energy-saving solution with the characteristics of both open source and cost-saving. The present invention is suitable for desalination operations in large tracts of saline-alkali land, and is very beneficial for saline-alkali land areas with simple on-site construction conditions, difficult water and power supply, and lack of infrastructure.

[0060] Optionally, Figure 6 Schematic diagram of the structure of the desalination system provided by the second embodiment of the present invention. The desalination system further comprises: a circulation device for recycling the separated fresh water to spray the saline soil.

[0061] Compared with the first embodiment, this embodiment adds a circulation device 13 for recycling the separated fresh water to spray the saline soil to achieve resource reuse. The desalinated water after electrodialysis treatment is reused in the treatment system, further reducing the supply requirements of on-site water sources. The remaining structure and working principle can refer to the details of the desalination system in the first embodiment, which will not be repeated here.

[0062] The embodiment of the present invention utilizes temporary and short-term construction work on site to desalinate a large area of ​​saline soil. Through on-site modular desalination system treatment, the salt in the saline soil is collected into the electroosmosis device through multi-stage filtration by fresh water spraying, and the salt is completely removed.

[0063] Through the above technical solution, the desalination system includes a leaching device for holding saline soil; a spraying device for spraying the saline soil to wash away the salt in the saline soil; and an electrodialysis device, and the electrodialysis device is used to perform electrodialysis treatment on the salt-containing leaching liquid to separate fresh water and concentrated brine. The technical solution of the present invention uses fresh water to leach the saline soil, thereby washing out the salt in the saline soil, and separating the washed salt into fresh water and concentrated brine through the electrodialysis device, thereby achieving the purpose of fully decomposing the salt in the saline soil. At the same time, the separated fresh water can also be used for reuse, and the separated concentrated brine can further extract industrial salt, thereby achieving the purpose of energy saving and environmental protection.

[0064] On the other hand, the present invention also provides a desalination method, which comprises: spraying saline soil to wash away the salt in the saline soil; filtering the sprayed saline soil to obtain a salt-containing leaching solution; and performing electrodialysis treatment on the salt-containing leaching solution to separate fresh water and concentrated brine.

[0065] Furthermore, the desalination method includes: recycling the separated fresh water to spray the saline soil.

[0066] The desalination method is the same as the desalination process and effect in the desalination system. For details, please refer to the first embodiment and the second embodiment, which will not be described again.

[0067] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0068] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A desalination system, characterized in that: The desalination system comprises: Leaching device for holding saline soil; a spraying device, used for spraying the saline soil to flush the salt in the saline soil; and Electrodialysis unit, The leaching device is also used to filter the saline soil after spraying to obtain a salt-containing leaching liquid, and The electrodialysis device is used to perform electrodialysis treatment on the salt-containing leaching solution to separate fresh water and concentrated brine.

2. The desalination system according to claim 1, characterized in that: The leaching device comprises: A dump box for holding saline soil; A first filtering module, used for filtering saline soil in the saline leaching solution; and The second filtering module is used for secondary filtering of the saline soil in the salt-containing leaching liquid filtered by the first filtering module.

3. The desalination system according to claim 2, characterized in that: A first filter net is provided between the dump box and the first filter module, for preventing saline soil in the dump box from entering the first filter module; A second filter net is provided between the first filter module and the second filter module to prevent saline soil in the salt-containing leaching liquid filtered by the first filter module from entering the second filter module.

4. The desalination system according to any one of claims 2-3, characterized in that: The first filter module is filled with medium-coarse sand, and the second filter module is filled with gravel.

5. The desalination system according to claim 1, characterized in that: The dump box is a U-shaped structure with a top opening size larger than a bottom size.

6. The desalination system according to claim 1, characterized in that: The desalination system also includes: A circulation device is used for recycling the separated fresh water to spray the saline soil.

7. The desalination system according to claim 1, characterized in that: The desalination system also includes: The solar energy device is used to supply power to the spraying device, the leaching device and the electrodialysis device.

8. The desalination system according to claim 1, characterized in that: The leaching device is connected to the electrodialysis device via a detachable tube.

9. A desalination method, characterized in that: The desalination method comprises: Spraying saline soil to flush out the salt in the saline soil; filtering the saline soil after spraying to obtain a saline leachate; and The salt-containing leaching solution is subjected to electrodialysis treatment to separate fresh water and concentrated brine.

10. The desalination method according to claim 1, characterized in that: The desalination method comprises: recycling the separated fresh water to spray the saline soil.

Images