High-salinity wastewater zero-discharge recycling synergistic saline-alkali soil treatment device

Abstract

The utility model particularly relates to a high-salinity wastewater zero-discharge recycling synergistic saline-alkali soil treatment device which is characterized in that a high-salinity wastewater regulating reservoir is connected with the water inlet end of a wastewater pretreatment unit, and the water outlet end of the wastewater pretreatment unit is connected with the water inlet end of an RO (reverse osmosis) pre-concentration unit through a pipeline; the concentrated water end of the RO pre-concentration unit is connected with the water inlet end of the low-pressure nanofiltration salt separation unit through a pipeline, the concentrated water end of the low-pressure nanofiltration salt separation unit is connected with the inlet end of the sodium sulfate salt water blending tank, and the water outlet end of the sodium sulfate salt water blending tank is connected with the inlet end of the replacement reaction device through a pipeline; the discharge end of the double-decomposition reaction device is connected with the compound mixing device through a pipeline, the water production end of the low-pressure nanofiltration salt separation unit is connected with the inlet end of the ultra-multiple RO concentration unit, the concentrated water end of the ultra-multiple RO concentration unit is connected with the inlet end of the saturated sodium chloride brine blending tank, and the outlet end of the saturated sodium chloride brine blending tank is connected with the ionic membrane electrolytic cell. The device is reasonable in structure and high in resource utilization rate.

Description

Technical Field

[0001] The utility model belongs to the technical field of saline-alkali land treatment, and specifically relates to a high-salt wastewater zero-discharge resource-based coordinated saline-alkali land treatment device. Background Art

[0002] Currently, the most effective method for managing saline-alkali soils is soil leaching, which consumes significant amounts of freshwater. Brine generated by agricultural irrigation and leaching of salt from saline-alkali land, as well as agricultural non-point source pollution, accounts for approximately 30% of total irrigation water. Discharge into rivers and lakes poses a serious threat to the water environment and ecology of the basin, and leads to the continuous worsening of secondary soil salinization. The national government has strictly prohibited the discharge of brine, making leaching a non-point source of pollution in saline-alkali lands impossible.

[0003] The inventor of this application, Cao Cheng, applied to the Patent Office of China for a utility model patent entitled "A Zero Discharge Device for High-salt Wastewater" on January 16, 2023. The patent was authorized and announced on May 26, 2023, with the authorization announcement number CN219079306U. It abandons the nanofiltration salt separation and subsequent RO re-concentration, ED concentration, evaporation and freezing crystallization process sections in the existing high-salt wastewater zero discharge device, greatly reducing the investment and operating costs of environmental protection facilities. At the same time, it uses chemical technology to achieve high-salt wastewater pollutant emission reduction and resource utilization, and uses RO concentrated concentrated water or nanofiltration salt separation after water and concentrated water as one of the raw materials for chemical production to produce industrial-grade baking soda, ammonium chloride, ammonium sulfate or potassium sulfate, realizing the transformation of negative benefits into positive benefits, while taking into account ecological protection and economic benefits, and promoting environmental protection projects to truly achieve synergistic efficiency in pollution control, emission reduction and carbon reduction and long-term sustainable operation.

[0004] The above technical solutions still have the defects of small output products and low resource utilization.

[0005] Increasing the output products of high-salt wastewater zero-discharge treatment technology, improving the degree of resource utilization, and synergistically combining high-salt wastewater zero-discharge treatment and saline-alkali land management have become technical problems that technical personnel in this field urgently need to solve. Utility Model Content

[0006] The purpose of this utility model is to provide a high-salt wastewater zero-discharge resource-based coordinated saline-alkali land treatment device, which realizes the resource utilization of unconventional "new water sources" such as saline-alkali land washing brine and agricultural non-point source pollution water. At the same time, it produces products such as sodium hydroxide, chlorine, hydrogen, baking soda, ammonium sulfate or potassium sulfate, realizing the recycling of high-salt waste liquid and industrial waste salt, completely solving the dilemma of high-salt wastewater discharge from saline-alkali land washing brine desalination, and realizing high-level utilization of water resources by quality gradient, with significant ecological, economic and social benefits.

[0007] The utility model is realized through the following technical solutions:

[0008] That is, a high-salt wastewater zero-discharge resource-based coordinated saline-alkali land treatment device, which is characterized by comprising a high-salt wastewater regulating and storage pool, the outlet end of the high-salt wastewater regulating and storage pool is connected to the water inlet end of the wastewater pretreatment unit through a pipeline, the outlet end of the wastewater pretreatment unit is connected to the water inlet end of the RO pre-concentration unit through a pipeline, the concentrated water end of the RO pre-concentration unit is connected to the water inlet end of the low-pressure nanofiltration salt separation unit through a pipeline, the concentrated water end of the low-pressure nanofiltration salt separation unit is connected to the inlet end of the sodium sulfate brine mixing tank, the outlet end of the sodium sulfate brine mixing tank is connected to the inlet end of the double decomposition reaction device through a pipeline, the discharge end of the double decomposition reaction device is connected to the compound mixing device through a pipeline, and the low-pressure nanofiltration salt separation unit is connected to the inlet end of the sodium sulfate brine mixing tank. The water production end of the salt filtration unit is connected to the inlet end of the super RO concentration unit, the concentrated water end of the super RO concentration unit is connected to the inlet end of the saturated sodium chloride brine mixing tank, the outlet end of the saturated sodium chloride brine mixing tank is connected to the ion membrane electrolyzer, the RO pre-concentration unit, the super RO concentration unit and the water production end of the double decomposition reaction device, and the discharge end of the compound mixing device are respectively connected to the saline-alkali land treatment unit through pipelines, the brine washing water and polluted water generated by the saline-alkali land treatment unit are connected to the water inlet end of the brine washing water and agricultural non-point source pollution water collection unit through pipelines, and the water outlet end of the brine washing water and agricultural non-point source pollution water collection unit is connected to the water inlet end of the high-salt wastewater storage tank through management.

[0009] The high-salt wastewater regulating and storage tank, wastewater pretreatment unit, RO pre-concentration unit, low-pressure nanofiltration salt separation unit, sodium sulfate brine mixing tank, double decomposition reaction device, saline-alkali land treatment unit, and salt water washing and agricultural non-point source pollution water collection unit of the utility model form a closed circulation loop to achieve zero discharge of wastewater.

[0010] High-salt wastewater is pre-treated in the wastewater pretreatment unit to remove hardness, impurities and reduce COD, and then concentrated in the RO pre-concentration unit. The concentrated brine is separated by nanofiltration and divided into two production sections. Section 1: The nanofiltration water is sodium chloride concentrated brine as the production raw material, sodium chloride is added to prepare saturated brine, and sodium hydroxide, chlorine and hydrogen are produced through the ion membrane electrolysis process; Section 2: The nanofiltration concentrated water is sodium sulfate concentrated brine as the production raw material, ammonium bicarbonate is added, and baking soda and ammonium sulfate are produced through the reactor.

[0011] In the above scheme, brackish water, high-salt wastewater, saline-alkali land washing wastewater, and agricultural non-point source pollution are treated by this device. The resulting desalinated water is used for industrial and agricultural irrigation, as well as saline-alkali land treatment and leaching. The agricultural non-point source pollution water generated by agricultural irrigation and saline-alkali land leaching is recycled, achieving water resource recycling and salt and nitrogen recycling. The sodium hydroxide, chlorine, hydrogen, and baking soda produced by this device are supplied to the market. Ammonium sulfate is also used in combination with additives to manufacture compound nitrogen fertilizer for saline-alkali land and market supply.

[0012] The reactor and crystallizer of the double decomposition reaction device of the present invention are both mature commercial products in the prior art, and those skilled in the art are aware of their structures and usage methods.

[0013] The compound mixing device of the present invention can use a compound fertilizer granulation production device known in the prior art, such as, but not limited to, the invention patent technology of a novel compound fertilizer granulation production system, which was published by the Patent Office of China on December 24, 2014, with publication number CN104230438A.

[0014] The compound mixing device of the utility model uses ready-made single fertilizers, compound fertilizers or chemical raw materials (such as urea, ammonium phosphate, potassium chloride, potassium sulfate, calcium sulfate, ammonium sulfate, ammonium chloride, etc.) as raw materials, supplemented with additives, and mixes, processes and granulates to produce fertilizers.

[0015] The saline-alkali land treatment unit of the present invention refers to the treatment of saline-alkali land by using saline-alkali land treatment methods known in the prior art. For example, saline-alkali land is repaired by physical means such as soil addition, sand pressing, terraced fields, water pressure salt removal, film covering, straw covering, etc., and chemical measures such as adding organic acid, inorganic acid, desulfurization gypsum, aluminum sulfate, biochar, furfural residue, organic polymers, biological strains, organic fertilizers, and plant repair measures to achieve the goals of desalination, salt washing, salt removal, and salt control, thereby making saline-alkali land arable, and selecting salt-alkali tolerant crops such as cotton, rice, sugar beets, and forage grass to increase production and efficiency.

[0016] The utility model discloses a salt water washing and agricultural non-point source pollution water collection unit, which is a discharge collection pipeline system for collecting saline-alkali land salt washing wastewater and farmland pollution water.

[0017] Furthermore, the outlet end of the reactor of the double decomposition reactor of the present invention is connected to the inlet end of the saturated sodium chloride brine preparation tank through a pipeline.

[0018] In the above scheme, high-salt wastewater is pretreated by the wastewater pretreatment unit to remove hardness, impurities and reduce COD, and then concentrated by the RO pre-concentration unit. The concentrated brine is separated by nanofiltration and divided into two production sections. Section one: the nanofiltration water is sodium chloride concentrated brine as the production raw material, sodium chloride is added to prepare saturated brine, and sodium hydroxide, chlorine and hydrogen are produced through the ion membrane electrolysis process; Section two: the nanofiltration concentrated water is sodium sulfate concentrated brine as the production raw material, potassium chloride is added, and potassium sulfate is produced through the reactor. The saturated sodium chloride solution produced at the same time is used as the raw material for production section one.

[0019] In the above scheme, brackish water, high-salt wastewater, saline-alkali land washing wastewater, and agricultural non-point source pollution are treated by this device. The resulting desalinated water is used for industrial and agricultural irrigation, as well as saline-alkali land treatment and leaching. The agricultural non-point source pollution water generated by agricultural irrigation and saline-alkali land leaching is recycled, achieving water resource recycling and salt and nitrogen recycling. The produced sodium hydroxide, chlorine, hydrogen, and other products are supplied to the market. At the same time, potassium sulfate is compounded with additives to produce high-potassium compound fertilizer, which is applied to saline-alkali land and supplied to the market.

[0020] The utility model has a reasonable structure and high resource utilization, does not produce any secondary pollution such as industrial waste salt and hazardous waste mother liquor salt, realizes the resource utilization of unconventional "new water sources" such as saline-alkali land washing brine and agricultural non-point source pollution water, and simultaneously produces sodium hydroxide, chlorine, hydrogen, baking soda, ammonium sulfate or potassium sulfate and other products, realizes the recycling of high-salt waste liquid and industrial waste salt, completely solves the dilemma of high-salt wastewater discharge in the desalination of saline-alkali land washing brine, realizes high-level utilization of water resources by quality gradient, and has significant ecological environmental benefits, economic benefits and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic structural diagram of Example 1 of the present utility model;

[0022] Figure 2 This is a schematic structural diagram of Example 2 of the present utility model;

[0023] As shown in the figure: 1. High-salt wastewater storage tank; 2. Wastewater pretreatment unit; 3. RO pre-concentration unit; 4. Low-pressure nanofiltration salt separation unit; 5. Sodium sulfate brine mixing tank; 6. Double decomposition reaction device; 7. Super RO concentration unit; 8. Saturated sodium chloride brine mixing tank; 9. Ion membrane electrolyzer; 10. Compound mixing device; 11. Saline-alkali land treatment unit; 12. Wash brine and agricultural non-point source pollution water collection unit. DETAILED DESCRIPTION

[0024] The following is a detailed description of the embodiments of the technical solution of the present invention in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and are therefore only examples and are not intended to limit the scope of protection of the present invention. It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs. Example 1

[0025] like Figure 1As shown: the high-salt wastewater storage tank 1, the wastewater pretreatment unit 2, the RO pre-concentration unit 3, and the low-pressure nanofiltration salt separation unit 4-2 are connected in sequence with pipelines. The water production end of the low-pressure nanofiltration salt separation unit 4-2 is connected to the inlet end of the sodium sulfate brine mixing tank 5 through a pipeline, and the outlet end of the sodium sulfate brine mixing tank 5 is connected to the inlet end of the double decomposition reaction device 6 through a pipeline. The concentrated water end of the low-pressure nanofiltration salt separation unit 4-2 is connected to the inlet end of the super-RO concentration unit 7 through a pipeline. The concentrated water end of the super-RO concentration unit 7 is connected to the inlet end of the saturated sodium chloride brine mixing tank 8 through a pipeline, and the outlet end of the sodium chloride brine mixing tank 8 is connected to the inlet end of the double decomposition reaction device 6 through a pipeline. It is connected to the ion membrane electrolyzer 9, the crystallizer discharge port of the double decomposition reaction device 6 is connected to the feed port of the compounding and mixing device 10 through a pipeline, the discharge port of the compounding and mixing device 10 is connected to the saline-alkali land treatment unit 11 through a pipeline, the water produced by the RO pre-concentration unit 3 and the super-RO concentration unit 7, and the condensed water of the double decomposition reaction device 5 are respectively connected to the saline-alkali land treatment unit 11 through pipelines, and the saline-alkali land washing brine and agricultural non-point source pollution water generated during the treatment of the saline-alkali land treatment unit 11 are collected by the washing brine and agricultural non-point source pollution water collection unit 12, and sent back to the high-salt wastewater storage tank 1 through a pipeline to form a circulation loop.

[0026] When used in this embodiment, saline-alkali land salt washing wastewater, agricultural non-point source pollution water, brackish water and high-salt wastewater enter the wastewater pretreatment unit 2 through the high-salt wastewater storage tank 1 to remove hardness, impurities and reduce COD, and then enter the RO pre-concentration unit 3. The produced water is reused for industrial and saline-alkali land leaching; the concentrated water passes through the low-pressure nanofiltration salt separation unit 4-2, and the produced water is sodium chloride concentrate and sodium sulfate concentrate. The subsequent production process is divided into two sections. Section 1: The nanofiltration produced water is sodium chloride concentrated brine, which is further concentrated by the super-RO concentration unit 7. The produced water is used for industrial and saline-alkali land leaching; the concentrated water enters the saturated sodium chloride brine preparation tank 8 and sodium chloride is added for preparation to produce saturated sodium chloride brine as production raw material, which enters the ion membrane electrolyzer 9 to produce sodium hydroxide, chlorine and hydrogen through the ion membrane electrolysis process. Stage 2: The nanofiltration concentrate is used as a raw material for production, using sodium sulfate brine as the raw material. After being prepared in sodium sulfate brine preparation tank 5, ammonium bicarbonate is added to the mixture, and sodium bicarbonate (sodium bicarbonate) is precipitated and crystallized through double decomposition reaction unit 6. The filtrate is evaporated and salt is precipitated, and ammonium sulfate is precipitated after cooling. The evaporated condensate is used for industrial and saline-alkali land washing. The ammonium sulfate enters the compounding and mixing unit 10, where it is mixed with additives to form a compound nitrogen fertilizer, which is applied to saline-alkali land. The saline-alkali land salt washing wastewater and agricultural non-point source pollution water generated by saline-alkali land remediation and development are collected in the salt washing and agricultural non-point source pollution collection unit 12 and circulated back to the high-salinity wastewater storage tank 1, forming a closed-loop cycle. Example 2

[0027] like Figure 2As shown: the outlet end of the reactor of the metathesis reactor 6 is connected to the inlet end of the saturated sodium chloride brine preparation tank 8 through a pipeline, and the rest is the same as in Example 2.

[0028] When used in this embodiment, saline-alkali land salt washing wastewater, agricultural non-point source pollution water, brackish water and high-salt wastewater enter the wastewater pretreatment unit 2 through the high-salt wastewater storage tank 1 to remove hardness, impurities and reduce COD, and then enter the RO pre-concentration unit 3. The produced water is reused for industrial and saline-alkali land leaching; the concentrated water passes through the low-pressure nanofiltration salt separation unit 4-2, and the produced water is sodium chloride concentrate and sodium sulfate concentrate. The subsequent production process is divided into two sections. Section 1: The nanofiltration produced water is sodium chloride concentrated brine, which is further concentrated by the super-RO concentration unit 7. The produced water is used for industrial and saline-alkali land leaching; the concentrated water enters the saturated sodium chloride brine preparation tank 8 and sodium chloride is added for preparation to produce saturated sodium chloride brine as production raw material, which enters the ion membrane electrolyzer 9 to produce sodium hydroxide, chlorine and hydrogen through the ion membrane electrolysis process. Stage 2: The nanofiltration concentrate is used as a production raw material, which is then blended in the sodium sulfate brine blending tank 5. Potassium chloride is added and passed through a double decomposition reactor 6 to generate a saturated sodium chloride solution. This saturated sodium chloride solution enters the saturated sodium chloride brine blending tank 8 for blending, creating saturated sodium chloride brine as a production raw material. This saturated sodium chloride solution then enters the ion-exchange membrane electrolysis cell 9, where it undergoes an ion-exchange membrane electrolysis process to produce sodium hydroxide, chlorine, and hydrogen. The filtrate evaporates, precipitates salt, and cools to precipitate potassium sulfate. The evaporated condensate is recycled for industrial use and saline-alkali land leaching. The potassium sulfate enters a compounding and mixing unit 10, where it is combined with additives to form a high-potassium compound fertilizer for application to saline-alkali land. The saline-alkali land salt washing wastewater and agricultural non-point source pollution water generated by saline-alkali land remediation and development are collected in the brine washing and agricultural non-point source pollution collection unit 12 and then circulated back to the high-salinity wastewater storage tank 1, forming a closed-loop system.

[0029] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention.

Claims

1. A high-salt wastewater zero-discharge resource-based collaborative saline-alkali land treatment device, characterized in that The invention comprises a high-salt wastewater regulating and storage pool, wherein the outlet end of the high-salt wastewater regulating and storage pool is connected to the water inlet end of the wastewater pretreatment unit through a pipeline, the outlet end of the wastewater pretreatment unit is connected to the water inlet end of the RO pre-concentration unit through a pipeline, the concentrated water end of the RO pre-concentration unit is connected to the water inlet end of the low-pressure nanofiltration salt separation unit through a pipeline, the concentrated water end of the low-pressure nanofiltration salt separation unit is connected to the inlet end of the sodium sulfate brine mixing tank, the outlet end of the sodium sulfate brine mixing tank is connected to the inlet end of the double decomposition reaction device through a pipeline, the discharge end of the double decomposition reaction device is connected to the compound mixing device through a pipeline, the water production end of the low-pressure nanofiltration salt separation unit is connected to the super RO The inlet end of the concentration unit is connected, the concentrated water end of the super RO concentration unit is connected to the inlet end of the saturated sodium chloride brine mixing tank, the outlet end of the saturated sodium chloride brine mixing tank is connected to the ion membrane electrolyzer, the RO pre-concentration unit, the super RO concentration unit and the water production end of the double decomposition reaction device, and the discharge end of the compound mixing device are respectively connected to the saline-alkali land treatment unit through pipelines, the brine washing water and polluted water generated by the saline-alkali land treatment unit are connected to the water inlet end of the brine washing water and agricultural non-point source pollution water collection unit through pipelines, and the water outlet end of the brine washing water and agricultural non-point source pollution water collection unit is connected to the water inlet end of the high-salt wastewater storage tank through management.

2. The high-salt wastewater zero-discharge resource-based collaborative saline-alkali land treatment device according to claim 1 is characterized in that The outlet end of the reactor of the double decomposition reactor is connected to the inlet end of the saturated sodium chloride brine preparation tank through a pipeline.

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