Seawater desalination and comprehensive treatment device for saline-alkali soil

Abstract

The utility model belongs to the technical field of saline-alkali land treatment, and particularly relates to a seawater desalination and saline-alkali land comprehensive treatment device which is characterized by comprising a seawater desalination membrane unit, the concentrated water end of the seawater desalination membrane unit is connected with a forward osmosis membrane pool through a pipeline, and the forward osmosis membrane pool is further connected with a high-concentration liquid fertilizer input pipe; a forward osmosis membrane unit is arranged in the forward osmosis membrane tank and further connected with a saline-alkali soil treatment unit through a pipeline, the saline-alkali soil treatment unit is further connected with an agricultural electricity irrigation water deep treatment device through a pipeline, and the wastewater end of the saline-alkali soil treatment unit is connected with the water inlet end of a brackish water desalination membrane unit through a pipeline. The concentrated water end of the brackish water desalination membrane unit is connected with the water inlet end of the seawater desalination membrane unit through a pipeline. The device has the advantages of being reasonable in structure, safe, environmentally friendly and good in coastal saline-alkali land treatment effect.

Description

Technical Field

[0001] The utility model belongs to the technical field of saline-alkali land treatment, and in particular relates to a device for comprehensive treatment of saline-alkali land in coordination with seawater desalination. 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] Membrane desalination technology is currently the most mature and widely used desalination technology. Forward osmosis is a new membrane separation process. Compared to commonly used membrane separation technologies such as ultrafiltration, microfiltration, and reverse osmosis, it does not require external pressure as a driving force for separation (or can operate at lower external pressure). Instead, it relies on the solution's own osmotic pressure difference to drive the forward osmosis separation process. It offers significant advantages such as low energy consumption, high recovery rates, and relatively low membrane fouling, making it a new hotspot in water treatment research. Utility Model Content

[0004] The purpose of the utility model is to provide a seawater desalination and saline-alkali land comprehensive treatment device, which is based on membrane seawater desalination and forward osmosis technology to treat saline-alkali land washing brine and agricultural non-point source pollution water, and produce diluted low-concentration liquid fertilizer for saline-alkali land fertilization, thereby realizing pollution-free treatment of saline-alkali land on the seaside.

[0005] The utility model is realized through the following technical solutions:

[0006] That is, a seawater desalination and saline-alkali land comprehensive treatment device, which is characterized by including a seawater desalination membrane unit, the concentrated water end of the seawater desalination membrane unit is connected to the forward osmosis membrane pool through a pipeline, the forward osmosis membrane pool is also connected to the high-concentration liquid fertilizer input pipe, the forward osmosis membrane unit is arranged in the forward osmosis membrane pool, the forward osmosis membrane unit is also connected to the saline-alkali land treatment unit through a pipeline, the saline-alkali land treatment unit is also connected to the agricultural electricity irrigation water deep treatment device through a pipeline, the wastewater end of the saline-alkali land treatment unit is connected to the water inlet end of the brackish water desalination membrane unit through a pipeline, and the concentrated water end of the brackish water desalination membrane unit is connected to the water inlet end of the seawater desalination membrane unit through a pipeline.

[0007] Principle of this utility model:

[0008] Municipal wastewater treatment plants discharge wastewater that meets standards, or other freshwater sources, through the agricultural irrigation water deep treatment unit, are treated to meet agricultural irrigation water standards and then used for agricultural irrigation and saline-alkali land treatment and leaching. The resulting agricultural non-point source polluted water and saline-alkali land salt washing wastewater are desalinated by the brackish water desalination membrane unit, and the desalinated water is reused for industrial use, achieving water resource recycling. The brine produced by the brackish water desalination membrane unit is mixed with seawater and fed into the seawater desalination membrane system. The desalinated water is then reused for industrial use, continuing the water recycling process. The brine produced by the seawater desalination membrane unit enters the forward osmosis membrane tank, serving as the feed liquid for the forward osmosis membrane unit. High-concentration liquid fertilizer serves as the draw liquid for the forward osmosis membrane unit. Driven by the forward osmotic pressure differential, water molecules permeate the forward osmosis membrane into the draw liquid side. The concentrated feed liquid, i.e., high-concentration seawater, is discharged from the system into the sea discharge pipeline. The diluted draw liquid, i.e., low-concentration liquid fertilizer, is transported and applied to farmland or saline-alkali land.

[0009] The seawater desalination membrane unit of the present invention is a membrane seawater desalination device known in the prior art, such as, but not limited to, the invention patent technology of a low-pressure membrane seawater desalination device disclosed by the China Patent Office on October 23, 2020, with publication number CN111807473A.

[0010] The forward osmosis membrane unit of the present invention is a forward osmosis membrane device known in the prior art, such as, but not limited to, the forward osmosis membrane unit in the invention patent technology of the invention patent with publication number CN102974218A, entitled "A Forward Osmosis Membrane Reactor and Integrated Seawater Desalination System and Seawater Desalination Process" published by the Patent Office of China on March 20, 2013.

[0011] 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.

[0012] The farmland irrigation water deep treatment device of the present invention is a high-efficiency fiber filter or ultrafiltration micro-membrane filter with mature existing technology and available on the market. The tail water discharged by the municipal sewage treatment plant that meets the discharge standards is filtered through the high-efficiency fiber or ultrafiltration membrane to make its water quality meet the water quality requirements of farmland irrigation water.

[0013] The brackish water desalination membrane unit of the present invention is a brackish water desalination device known in the prior art, such as, but not limited to, the utility model patent technology of a brackish water desalination device for agricultural use, with publication number CN2905777Y, published by the Patent Office of China on May 30, 2007.

[0014] The utility model has the advantages of reasonable structure, safety, environmental protection and good effect of treating coastal saline-alkali land.

[0015] 1) Treating saline-alkali land washing brine and agricultural non-point source pollution water solves the problem that saline-alkali land washing brine and agricultural non-point source pollution water cannot be directly discharged, which is safe and environmentally friendly;

[0016] 2) The diluted, low-concentration liquid fertilizer produced is used for fertilizing saline-alkali land, which helps to manage saline-alkali land. Integrated water and fertilizer technology involves fertilizing and watering crops through an irrigation system. Crops absorb nutrients while absorbing water, making it one of the most water- and fertilizer-saving technologies in agricultural production. Irrigation water containing fertilizer is sprayed onto crops or dripped into the root zone through sprinklers (sprinklers, micro-sprinklers, and drippers, etc.). Broadly speaking, it involves dissolving the fertilizer and applying it, including drench application, pouring, spraying, and pipe application. Fertilization of saline-alkali land mainly involves increasing the application of organic fertilizers, applying liquid fertilizers or water-soluble fertilizers, and improving the utilization rate of chemical fertilizers, reducing the amount of chemical fertilizers used, and alleviating soil compaction, which is effective in improving saline-alkali land. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural diagram of the utility model;

[0018] As shown in the figure: 1. Agricultural irrigation water deep treatment unit; 2. Brackish water desalination membrane unit; 3. Seawater desalination membrane unit; 4. Forward osmosis membrane pool; 5. Forward osmosis water pump; 6. Forward osmosis membrane unit; 7. Saline-alkali land treatment unit. DETAILED DESCRIPTION

[0019] 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.

[0020] like Figure 1As shown: the saline-alkali land treatment unit 7 is connected to the agricultural power irrigation water deep treatment device 1 through a pipeline, the agricultural power irrigation water deep treatment device 1 is connected to the municipal sewage treatment plant's qualified tail water and other fresh water source input pipes, the wastewater end of the saline-alkali land treatment unit 7 is connected to the water inlet end of the brackish water desalination membrane unit 2 through a pipeline, the concentrated water end of the brackish water desalination membrane unit 2 is connected to the water inlet end of the seawater desalination membrane unit 3 through a pipeline, the water inlet end of the seawater desalination membrane unit 3 is also connected to the seawater intake pipeline, the concentrated water end of the seawater desalination membrane unit 3 is connected to the forward osmosis membrane pool 4 through a pipeline, one side of the forward osmosis membrane pool 4 is connected to the sea discharge pipeline, a forward osmosis membrane unit 6 is provided inside the forward osmosis membrane pool 4, one side of the forward osmosis membrane unit 6 is connected to the high-concentration liquid fertilizer input pipe, and the other side is connected to the saline-alkali land treatment unit 7 through a pipeline, and a forward osmosis water pump 5 is provided on the above pipeline.

[0021] When the utility model is used, the sewage discharged by the municipal sewage treatment plant or other fresh water sources that meets the standards is used for agricultural irrigation and saline-alkali land treatment and leaching after passing through the farmland irrigation water deep treatment unit 1 to meet the agricultural irrigation water standards. The agricultural non-point source pollution water and saline-alkali land salt washing wastewater generated are desalinated by the brackish water desalination membrane unit 2, and the desalinated water is reused for industrial water. The concentrated water generated by the brackish water desalination membrane unit 2 and the seawater are mixed and enter the seawater desalination membrane unit 3. The water produced by the seawater desalination membrane unit 3 is reused for industrial water. The concentrated water of the seawater desalination membrane unit 3 enters the forward osmosis membrane pool 4 as the raw material liquid of the forward osmosis membrane unit 6, and the high-concentration liquid fertilizer is used as the draw liquid of the forward osmosis membrane unit 6. Driven by the forward osmosis pressure difference, water molecules pass through the forward osmosis membrane and enter the draw liquid side. The raw material liquid is discharged into the sea discharge pipeline. The diluted draw liquid, i.e., the low-concentration liquid fertilizer, is transported by the forward osmosis water pump 5 for application to farmland or saline-alkali land.

[0022] 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 device for comprehensive management of seawater desalination and saline-alkali land, characterized in that It includes a seawater desalination membrane unit, the concentrated water end of the seawater desalination membrane unit is connected to the forward osmosis membrane pool through a pipeline, the forward osmosis membrane pool is also connected to the high-concentration liquid fertilizer input pipe, the forward osmosis membrane unit is arranged in the forward osmosis membrane pool, the forward osmosis membrane unit is also connected to the saline-alkali land treatment unit through a pipeline, the saline-alkali land treatment unit is also connected to the agricultural electricity irrigation water deep treatment device through a pipeline, the wastewater end of the saline-alkali land treatment unit is connected to the water inlet end of the brackish water desalination membrane unit through a pipeline, and the concentrated water end of the brackish water desalination membrane unit is connected to the water inlet end of the seawater desalination membrane unit through a pipeline.

Images