Brackish water concentration treatment method and device

Abstract

The invention provides a brackish water concentration treatment method and a brackish water concentration treatment system, and the brackish water concentration treatment method comprises the following steps: carrying out homogenization regulation on brackish water, and then carrying out precipitation by using an auxiliary agent to remove inorganic matters and suspended matters in the brackish water so as to obtain precipitated brackish water; carrying out primary treatment on the precipitated brackish water to remove hardness ions in the brackish water so as to obtain primary treatment wastewater; performing membrane treatment on the primarily treated brackish water to further improve the water quality of the brackish water; and carrying out step-by-step concentration treatment on the brackish water subjected to membrane treatment to generate clear water and carnallite for recycling. According to the method, the salt content in the brackish water can be reduced, efficient purification and resource utilization of the brackish water are realized, and environmental pollution and waste of fresh water resources are also reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of brackish water treatment, and in particular to a brackish water concentration treatment method and a system thereof. Background Art

[0002] The availability of freshwater resources is extremely limited worldwide. Although about three-quarters of the Earth's surface is covered by water, the freshwater resources that are directly available to humans only account for 0.325% of the world's total water resources. With the continuous growth of the global population and the increasing intensity of industrial activities, the shortage of freshwater resources has become more and more serious. Especially in my country, the per capita water resources are far below the world average, only one-fourth, and the geographical distribution of water resources is extremely uneven.

[0003] In this situation of water shortage, brackish water has gradually attracted people's attention as a potential substitute for freshwater resources. Brackish water refers to water resources with high mineralization, difficult to use directly or with limited scope of use. According to its salt content, brackish water can be subdivided into slightly salty water (1-3g / L), brackish water (3-5g / L), medium-salinity brackish water (5-10g / L) and high-salinity brackish water (above 10g / L). This type of water resource not only tastes bad, but long-term drinking may also have adverse effects on human health. Therefore, it is not suitable as a direct drinking water source for humans and animals.

[0004] However, compared with seawater, brackish water has a relatively low salt content, which means that the energy consumption required in the desalination process is also relatively low. Therefore, from a technical and economic point of view, brackish water treatment technology is expected to become an effective means to alleviate the shortage of freshwater resources. In my country, brackish water resources are widely distributed. According to statistics, the amount of exploitable brackish water resources is as high as 20 billion cubic meters per year, which provides broad space and potential for the development and utilization of brackish water resources.

[0005] In particular, Xinjiang, as an important region in northwest my country, has a vast geographical space and abundant water resources, but the water resources are affected by seasonal factors, and the temporal and spatial distribution is extremely unbalanced; some groundwater and surface water in southern Xinjiang have salinization problems, which further aggravates the local water resource tension; in view of the importance of water resources to the economic development of Xinjiang and the suitable climatic conditions in southern Xinjiang, it is necessary to develop and utilize the bitter and salty water resources in Xinjiang to alleviate the local water shortage and promote economic development.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The first purpose of the present invention is to provide a method for concentrating brackish water. The core of the method is to convert brackish water with high mineralization and difficult to directly use into fresh water resources that can be used for human production and life, thereby effectively alleviating the problem of fresh water resource shortage.

[0008] The second object of the present invention is to provide a brackish water concentration treatment system, which can implement the above-mentioned brackish water concentration treatment method and is simple to operate, safe and environmentally friendly.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted: A method for concentrating brackish water comprises the following steps: The brackish water is first homogenized and adjusted, and then an auxiliary agent is used for precipitation to remove inorganic matter and suspended matter in the brackish water to obtain precipitated brackish water; the precipitated brackish water is then preliminarily treated to remove hardness ions in the brackish water to obtain preliminarily treated wastewater; the preliminarily treated brackish water is then treated with a membrane to further improve the water quality of the brackish water; the brackish water after the membrane treatment is then concentrated step by step to produce clean water and recycled miscellaneous salts.

[0010] Preferably, in the preliminary treatment, the wastewater after homogenization adjustment is sequentially clarified and filtered to remove suspended matter and hardness ions in the brackish water.

[0011] Preferably, the auxiliary agent used in the precipitation treatment is one or more of polyaluminium chloride and polyacrylamide.

[0012] Preferably, the chemical agents used in the clarification treatment are one or more of sodium carbonate and calcium hydroxide.

[0013] Preferably, the membrane treatment uses one or more of an ultrafiltration membrane and a reverse osmosis membrane.

[0014] Preferably, the step-by-step concentration treatment after the membrane treatment is a secondary treatment, wherein the primary treatment is to desalinate the brackish water after the membrane treatment to produce fresh water, and the secondary treatment is to evaporate water from the brackish water after the membrane treatment to achieve concentration of the brackish water.

[0015] First, the present invention ensures the stability of the brackish water quality through homogenization regulation, providing a stable foundation for subsequent treatment. The use of chemical agents such as polyaluminium chloride and polyacrylamide to assist precipitation treatment can effectively remove inorganic matter and suspended matter in the brackish water, significantly reduce the turbidity and suspended matter content of the water, and reduce the burden for subsequent treatment. The clarification treatment is combined with the filtration treatment, and chemical agents such as sodium carbonate and calcium hydroxide are used to react with hardness ions to generate insoluble precipitates. Further removal through filtration effectively reduces the hardness of the water body, avoiding structural and clogging problems in the subsequent membrane treatment process.

[0016] The use of membrane separation technologies such as ultrafiltration membranes and reverse osmosis membranes can further remove tiny particles, bacteria, viruses and soluble organic matter in the water, significantly improving the water quality to meet the discharge standards. The step-by-step concentration treatment not only achieves the concentration of brackish water, but also produces clear water and river salts through separation. Clear water can be reused, while the salts can be recycled according to their composition, achieving effective utilization of resources and friendly environmental protection. In addition, precipitation treatment and clarification treatment effectively remove most of the suspended matter and hardness ions, creating good water inlet conditions for membrane treatment, extending the service life of the membrane, and improving the efficiency and stability of membrane treatment.

[0017] The present invention also provides a brackish water concentration treatment system, comprising: A regulating unit, a preliminary treatment unit, a membrane treatment unit and a step-by-step concentration unit are arranged in sequence along the direction in which the brackish water flows in; The regulating unit includes a sedimentation regulating tank for homogenizing the brackish water, stabilizing the water quality and water volume of the brackish water, and removing inorganic matter and suspended matter from the sedimentation regulating tank through a sludge scraper in the regulating unit; The preliminary treatment unit is to remove large inorganic particles, suspended matter, hardness ions and colloids in brackish water to ensure the smooth progress of subsequent post-treatment steps; The membrane treatment unit uses a membrane component that can effectively remove small molecular organic matter and salt in brackish water, improve the water quality of the brackish water after preliminary treatment, and reduce pollution; The step-by-step concentration unit is used to treat the brackish water and concentrated water to obtain clean water and miscellaneous salts for recycling.

[0018] Preferably, the preliminary treatment unit comprises a clarification tank and a filtration tank; The clarifier tank contains a sludge scraping and sludge discharge unit capable of discharging the sludge generated in the clarifier tank; The filter tank is V-shaped and can further filter the brackish water discharged from the clarification tank to remove fine suspended matter and colloids.

[0019] Preferably, the step-by-step concentration unit contains an EDI system, and the brackish water after membrane treatment is step-by-step concentrated using the EDI system to obtain concentrated water, and the concentrated water is evaporated through a natural evaporation pool connected to the step-by-step evaporation equipment to obtain impure salts.

[0020] The sedimentation regulating tank in the regulating unit of the present invention effectively realizes the homogenization treatment of brackish water, and lays a solid foundation for subsequent treatment steps by stabilizing the water quality and water volume; the use of the scraper efficiently removes inorganic matter and suspended matter and discharges them out of the tank, ensuring the cleanliness of the water entering the subsequent treatment unit.

[0021] The combination of clarifier and filter tank in the preliminary treatment unit further purifies the brackish water. The clarifier not only removes large inorganic particles and suspended solids, but also effectively removes sludge through the scraping and sludge discharge units, avoiding the impact of sludge accumulation on the system; the use of V-shaped filter tank further filters out fine suspended solids and colloids, significantly improving the water quality.

[0022] In the membrane treatment unit, the introduction of membrane components realizes the effective removal of small molecular organic matter and salt. This step not only improves the water quality, but also creates favorable conditions for the subsequent step-by-step concentration steps. The use of membrane technology, with its high precision and efficiency, ensures the stability and reliability of the treatment effect.

[0023] The EDI system in the step-by-step concentration unit removes ions and organic matter from the water through the electric field and the selective permeability of the ion exchange membrane. The brackish water treated by the step-by-step concentration membrane is converted into high-quality concentrated water; this step not only improves the water utilization efficiency, but also reduces the energy consumption during the treatment process. Subsequently, the concentrated water enters the natural evaporation pool for evaporation, and finally obtains the impurities. This treatment process not only realizes the concentrated treatment of brackish water, but also realizes the effective recovery and utilization of resources.

[0024] Compared with the prior art, the present invention has the following beneficial effects: By adjusting the precipitation and the auxiliary use of chemical agents, the present invention can efficiently remove inorganic matter and suspended matter in brackish water, providing a good water quality foundation for subsequent treatment steps. Further treatment in the clarification tank and the filtration tank effectively removes large-particle inorganic matter, suspended matter, hardness ions and colloids in the brackish water to ensure the clarity and stability of the effluent water quality; the combined effect of these two steps ensures that the subsequent membrane treatment unit can operate more efficiently, prolongs the service life of the membrane, and improves the effluent water quality. The membrane treatment unit uses ultrafiltration membrane and reverse osmosis membrane to effectively remove small molecular organic matter and salt in the brackish water, further improving the water quality. The use of the step-by-step concentration unit, especially the EDI system, not only realizes the step-by-step concentration of the brackish water after membrane treatment, but also evaporates the water in the concentrated water through the natural evaporation tank, realizing the recycling of salt and solid matter. The synergistic effect of these two units not only improves the treatment efficiency of brackish water, but also maximizes the utilization of resources.

[0025] The overall design of the processing system of the present invention is reasonable, and the various units are closely connected, which not only improves the processing efficiency but also ensures the stable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] By describing the embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other purposes, features and advantages of the present application will become more apparent. The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings, the same reference numerals generally represent the same components or steps. Figure 1 A schematic diagram of the overall process of implementing a method for concentrating and treating brackish water provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be appreciated by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work, all belong to the scope of protection of the present invention. If specific conditions are not indicated in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0028] The present invention provides a method for concentrated treatment of brackish water. Specifically, the brackish water is first regulated in water quality and quantity through a sedimentation regulating tank, and at the same time, an appropriate amount of flocculants and coagulants are added to precipitate large-particle inorganic substances and suspended solids in the brackish water. The large-particle impurities in the brackish water are effectively removed through the dual effects of natural precipitation and chemical coagulants, providing more stable water inlet conditions for subsequent treatment links. The brackish water in the sedimentation regulating tank flows into a clarification tank, and chemical agents are added thereto to remove hardness ions in the brackish water. The water quality is further purified through chemical reactions in the clarification tank, reducing the hardness of the brackish water and alleviating the burden on subsequent membrane treatment links. The clear liquid in the clarification tank flows into the filtration tank for filtration treatment to remove fine suspended solids and colloids in the clear liquid, further improving the water quality. The clear liquid after filtration enters the purification pool in the membrane treatment unit, and then enters the ultrafiltration stage through the lifting pump. The ultrafiltration stage further improves the water quality, reduces pollution and blockage, and extends the service life of the membrane. Then the water body enters the reverse osmosis stage for treatment through the lifting pump. The ultrafiltration and reverse osmosis stages use membrane separation technology to achieve efficient removal of soluble salts, organic matter, microorganisms, etc. in the water, and produce high-quality reverse osmosis water. After the osmosis stage, clear water and concentrated water are produced. The concentrated water enters the EDI system for step-by-step concentration treatment. First, the primary treatment is mainly to desalinate the concentrated water to produce primary concentrated water and primary fresh water. The primary concentrated water then undergoes secondary treatment, which mainly concentrates the primary concentrated water to produce secondary fresh water and secondary concentrated water. The secondary concentrated water is further transported to the natural evaporation pool for evaporation treatment. The EDI system achieves efficient removal of salt in the concentrated water and further desalination of water through the combination of electrodialysis and ion exchange. The natural evaporation pool treats the concentrated water that cannot be reused, avoiding environmental pollution.

[0029] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention will be further explained below in conjunction with specific implementation methods.

[0030] Example 1 The mineralization degree in Alaer area in southern Xinjiang is relatively high, with an average mineralization degree (TDS) of 4193.17 mg / L, and the cations in the water are mainly Ca 2+ Mg 2+ Mainly, the anion is Cl - and SO4 2- The brackish water concentration treatment method of the present invention is used in this area according to the following steps: (1) First, brackish water with a TDS of 4193.17 mg / L is flowed into a sedimentation and adjustment tank at a flow rate of 1000 m³ / h. The tank has a large capacity to accommodate and adjust the water volume. Large particles are settled to the bottom by gravity. At the same time, polyaluminum chloride and polyacrylamide are added as flocculants and coagulants to accelerate the coagulation and sedimentation of particles, thereby obtaining brackish water after adjustment and precipitation. (2) The brackish water after adjustment and sedimentation is pumped out of the sedimentation and adjustment tank through a lifting pump and transported to the clarification tank. Sodium carbonate and sodium hydroxide are added to the clarification tank to react with the calcium and magnesium ions in the brackish water to form precipitates. The precipitates are discharged out of the tank through a sludge scraper and a sludge discharge unit. (3) After the effluent from the clarifier enters the V-type filter, the fine impurities in the water are trapped on the surface of the filter material through the filtering effect of the filter material. The filtered brackish water is clear and has high transparency. (4) The brackish water filtered by the V-type filter enters the purification tank, where it becomes more uniform and stable through natural sedimentation and mixing, providing more stable water quality for subsequent treatment; (5) After the water in the purification pool is transported to the ultrafiltration stage through the lifting pump, the tiny impurities in the water are trapped on the membrane surface through the filtering effect of the ultrafiltration membrane, further improving the purity of the brackish water and outputting ultrafiltration water; (6) The ultrafiltration water enters the reverse osmosis treatment, and the salt and impurities in the ultrafiltration water are retained on one side of the membrane through the reverse osmosis membrane, thereby generating pure reverse osmosis water and reverse osmosis concentrated water. The reverse osmosis water can be directly reused in production, and the TDS of the reverse osmosis water is 83.89 mg / L; (7) The reverse osmosis concentrate enters the EDI system, which is divided into two stages of treatment. The first stage of treatment is to desalinate the reverse osmosis concentrate to produce first-level fresh water and first-level concentrate. The first-level concentrate is then treated in the second stage to produce second-level fresh water and second-level concentrate. (9) After the secondary concentrated water produced by the EDI system is introduced into the natural evaporation pond, the water is evaporated through natural evaporation, and the remaining salt and solid matter are regularly treated and disposed of.

[0031] Example 2 The treatment system of the present invention was used in a water treatment plant in a certain area. The treatment steps were consistent with those in Example 1. The effluent water quality after continuous operation for 10 days was as shown in Tables 1 and 2.

[0032] Table 1. Statistical units of chemical components of brackish water: mg / L

[0033] Table 2. Water quality data of brackish water desalination effluent

[0034] From the above data, it can be seen that the brackish water concentration treatment method and system of the present invention can show that the quality of the brackish water has been significantly improved after treatment, the chemical components in the brackish water have also been greatly reduced, and the quality of the effluent is stable and meets the water use standards; and from the effluent quality of the treatment system of the present invention for 10 consecutive days, the system can stably and continuously output high-quality water, reducing the TDS value of the water to more than 200, and the output of water is relatively stable, with the daily water output being above 16,500 m³ and not fluctuating much. This shows that the present invention can show excellent adaptability and processing capabilities in brackish water areas with high mineralization, high hardness, and large water quality fluctuations.

[0035] Finally, it should be noted that 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 method for concentrating brackish water, characterized in that: The steps include: The brackish water is first homogenized and adjusted, and then an auxiliary agent is used for precipitation to remove inorganic matter and suspended matter in the brackish water to obtain precipitated brackish water; the precipitated brackish water is then preliminarily treated to remove hardness ions in the brackish water to obtain preliminarily treated wastewater; the preliminarily treated brackish water is then treated with a membrane to further improve the water quality of the brackish water; the brackish water after the membrane treatment is then concentrated step by step to produce clean water and recycled miscellaneous salts.

2. The method for concentrating brackish water according to claim 1, characterized in that: In the preliminary treatment, the wastewater after homogenization adjustment is clarified and filtered in sequence to remove suspended matter and hardness ions in the brackish water.

3. The method for concentrating brackish water according to claim 1, characterized in that: The auxiliary agent used in the precipitation treatment is one or more of polyaluminium chloride and polyacrylamide.

4. The method for concentrating brackish water according to claim 2, characterized in that: The chemical agents used in the clarification treatment are one or more of sodium carbonate and calcium hydroxide.

5. The method for concentrating brackish water according to claim 1, characterized in that: The membrane treatment adopts one or more of ultrafiltration membrane and reverse osmosis membrane.

6. The method for concentrating brackish water according to claim 1, characterized in that: The step-by-step concentration treatment after the membrane treatment is a secondary treatment. The primary treatment is to desalinate the brackish water after the membrane treatment to produce fresh water, and the secondary treatment is to evaporate water from the brackish water after the membrane treatment to achieve concentration of the brackish water.

7. A brackish water concentration treatment system according to any one of claims 1 to 6, characterized in that: include: A regulating unit, a preliminary treatment unit, a membrane treatment unit and a step-by-step concentration unit are arranged in sequence along the direction in which the brackish water flows in; The regulating unit includes a sedimentation regulating tank for homogenizing the brackish water, stabilizing the water quality and water volume of the brackish water, and removing inorganic matter and suspended matter from the sedimentation regulating tank through a sludge scraper in the regulating unit; The preliminary treatment unit is to remove large inorganic particles, suspended matter, hardness ions and colloids in brackish water to ensure the smooth progress of subsequent post-treatment steps; The membrane treatment unit uses a membrane component that can effectively remove small molecular organic matter and salt in brackish water, improve the water quality of the brackish water after preliminary treatment, and reduce pollution; The step-by-step concentration unit is used to treat the brackish water and concentrated water to obtain clean water and miscellaneous salts for recycling.

8. The brackish water concentration treatment system according to claim 7, characterized in that: The preliminary treatment unit comprises a clarification tank and a filtration tank; The clarifier tank contains a sludge scraping and sludge discharge unit capable of discharging the sludge generated in the clarifier tank; The filter tank is V-shaped and can further filter the brackish water discharged from the clarification tank to remove fine suspended matter and colloids.

9. The brackish water concentration treatment system according to claim 7, characterized in that: The step-by-step concentration unit contains an EDI system, which is used to step-by-step concentrate brackish water after membrane treatment to obtain concentrated water, and the concentrated water is evaporated through a natural evaporation pool connected to the step-by-step evaporation equipment to obtain impure salts.

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