System and method for treating high-salinity wastewater through hardness removal-cyclic regeneration coupled membrane concentration

Abstract

The invention discloses a system for treating high-salinity wastewater through hardness removal-cyclic regeneration coupled membrane concentration, which comprises a pretreatment unit connected with a continuous flow resin hardness removal unit, the continuous flow resin hardness removal unit is connected with an ultrafiltration unit, and the ultrafiltration unit is respectively connected with a multi-stage concentration unit and a product water output pipe. The multi-stage concentration unit is connected with an evaporative crystallization treatment unit; the system further comprises a saline water internal circulation regeneration unit which is respectively connected with the continuous flow resin hardness removal unit and the evaporative crystallization treatment unit. The invention also discloses a method for treating high-salinity water by using the system for treating high-salinity wastewater through hardness removal-cyclic regeneration coupled membrane concentration. According to the system for treating the high-salinity wastewater through hardness removal-cyclic regeneration coupled membrane concentration, the problem that in the prior art, the medicament cost is high is solved, resource utilization of calcium sulfate is achieved, the'salt 'load caused by the medicament adding amount is reduced, and the follow-up evaporative crystallization load is reduced.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a system for treating high-salinity wastewater by hard-circulation regeneration coupled membrane concentration, and also includes a method for treating high-salinity wastewater using the above system. Background Technology

[0002] High-mineralization saline wastewater typically originates from industrial production processes such as coal mining, petrochemicals, printing and dyeing, and pulp and paper making. This water generally contains high hardness and salt content, with hardness primarily manifested as calcium and magnesium ions. Currently, the conventional treatment process for high-mineralization saline wastewater mainly combines chemical precipitation and ion exchange resin methods. A large amount of hardness-reducing agent is added to lower the wastewater hardness to 100-150 mg / L, followed by further removal using ion exchange resin to meet the hardness requirements of membrane concentration and evaporation crystallization systems.

[0003] However, existing conventional processing techniques still have many problems: 1. In actual dosing, it is difficult to control the dosage of hardness removal agent in real time according to the hardness of the incoming water. Usually, the dosage is controlled according to the higher hardness value, which can easily lead to over-dosing of hardness removal agent and significantly increase the cost of the agent.

[0004] 2. Excessive addition of chemicals will increase the salinity of wastewater, increase the treatment load of membrane concentration and evaporation crystallization, and further increase investment and operating costs.

[0005] 3. If conventional cation exchange resin softening processes are used to treat high-hardness wastewater, the regeneration cycle will be greatly shortened, requiring frequent regeneration or a significant increase in resin loading, resulting in high investment and the need for large amounts of regeneration agents such as acids, alkalis, or salts, leading to resource waste.

[0006] 4. A combination of chemical precipitation and ion exchange resin methods is used to treat highly saline wastewater. Ion exchangers generally use fixed beds, but the combined bed type has low treatment efficiency, the amount of acid and alkali consumed during resin regeneration is still large, and the operating cost is high.

[0007] 5. High-mineralized saline wastewater produces a large amount of softened sludge after chemical softening treatment. The main components of chemical sludge are calcium carbonate and magnesium hydroxide. The recovery rate of by-product inorganic salts is low. At present, there are no very effective means of resource utilization. Generally, landfill disposal is used, which occupies land resources.

[0008] 6. The hardening removal unit in conventional treatment processes is affected by the hardening removal efficiency. The membrane flux in the membrane concentration section is generally not high, and the recovery rate is generally around 70-75%. In order to achieve high recovery rate of permeate, the process flow is lengthy.

[0009] In summary, with increasingly stringent environmental protection policies, conventional deep treatment and emission compliance methods can no longer meet the needs of enterprises. Furthermore, high treatment costs further constrain their production operations and high-quality development. Therefore, there is an urgent need for a new, highly efficient process and system for hardening removal and brine internal circulation regeneration coupled with membrane concentration to treat high-mineralized water, in order to achieve zero wastewater discharge and resource utilization, reduce operating costs, and improve treatment efficiency. Summary of the Invention

[0010] The purpose of this invention is to provide a system for treating high-salt wastewater by removing hardness and promoting regeneration through a coupled membrane. This system solves the problem of high reagent costs in existing technologies, realizes the resource utilization of calcium sulfate, reduces the "salt" load caused by reagent addition, and lowers the load of subsequent evaporation and crystallization.

[0011] A second objective of this invention is to provide a method for treating high-salinity water using the above-described system for concentrating and treating high-salinity wastewater via a hardening-recycling regeneration coupling membrane.

[0012] The first technical solution adopted in this invention is: a system for treating high-salt wastewater by hardening removal-circulation regeneration coupled membrane concentration, including a pretreatment unit, a continuous flow resin hardening removal unit connected to the pretreatment unit, an ultrafiltration unit connected to the continuous flow resin hardening removal unit, a multi-stage concentration unit and a product water output pipe connected to the ultrafiltration unit, and an evaporation crystallization treatment unit connected to the multi-stage concentration unit. It also includes a brine internal circulation regeneration unit, which is connected to the continuous flow resin hardening unit and the evaporation crystallization treatment unit.

[0013] The invention is further characterized by: The continuous flow resin hardening unit includes one resin exchange tower, two resin regeneration towers, and two resin washing towers, arranged in the following order: resin exchange tower, first resin regeneration tower, second resin regeneration tower, first resin washing tower, and second resin washing tower, in sequence. The resin exchange tower is connected to the pretreatment unit and the resin exchange tower is connected to the ultrafiltration unit.

[0014] The multi-stage concentration unit includes a primary concentration unit connected to the ultrafiltration unit, a secondary concentration unit connected to the primary concentration unit, a hardening and silica removal filtration unit connected to the secondary concentration unit, a tertiary concentration unit connected to the hardening and silica removal filtration unit, and an evaporation and crystallization treatment unit connected to the tertiary concentration unit. The primary, secondary, and tertiary concentration units are all connected to the product water output pipe through pipelines. Alternatively, the multi-stage concentration unit includes a primary concentration unit connected to the ultrafiltration unit, a secondary concentration unit connected to the primary concentration unit, a hardening and desiliconizing filtration unit connected to the secondary concentration unit, and an evaporation and crystallization treatment unit connected to the hardening and desiliconizing filtration unit. Both the primary and secondary concentration units are connected to the product water output pipe via pipelines.

[0015] The primary concentration unit includes a reverse osmosis unit, a nanofiltration unit, or an electrodialysis unit; the secondary concentration unit includes a reverse osmosis unit or a nanofiltration unit; and the tertiary concentration unit includes a reverse osmosis unit or a nanofiltration unit.

[0016] The hardening and silica removal filtration unit includes any combination of treatment units such as high-density pool-sand filtration-ultrafiltration unit, high-density pool-ultrafiltration unit, or reaction pool-tubular microfiltration or membrane softening unit.

[0017] The evaporation crystallization processing unit includes an evaporation unit, which is connected to a three-stage concentration unit or a hardening and silicon removal filtration unit. The evaporation unit is connected to a crystallization unit, which is connected to a freezing crystallization unit. The freezing crystallization unit is connected to a sodium chloride evaporation crystallization unit. The freezing crystallization unit is also connected to a pipeline between the evaporation unit and the crystallization unit. The freezing crystallization unit is also connected to a brine internal circulation regeneration unit through a pipeline. The sodium chloride evaporation crystallization unit is connected to a miscellaneous salt evaporation crystallization unit. Alternatively, the evaporation crystallization processing unit includes an evaporation unit connected to a three-stage concentration unit or a hardening and desiliconizing filtration unit. The evaporation unit is connected to a crystallization unit, which is connected to a mixed salt evaporation crystallization unit. The crystallization unit is also connected to a brine internal circulation regeneration unit via a pipeline.

[0018] The brine internal circulation regeneration unit includes a calcium sulfate reactor connected to the continuous flow resin hardening unit. The calcium sulfate reactor is also connected to a softening and filtration unit, which is also connected to the continuous flow resin hardening unit via a pipeline. The pipeline output from the crystallization unit or the freeze crystallization unit connects the pipeline between the continuous flow resin hardening unit and the softening and filtration unit.

[0019] The calcium sulfate reactor includes reaction devices such as a high-density tank, a mechanically accelerated clarification tank, and a calcium sulfate induced crystallizer; The softening and filtration unit includes any of the following treatment units: high-density tank-sand filtration-ultrafiltration unit, high-density tank-ultrafiltration unit, or reaction tank-tubular microfiltration or membrane softening unit.

[0020] The second technical solution adopted in this invention is: a high-mineralization water treatment method, which uses the above-mentioned hardening-circulation regeneration coupled membrane concentration system for treating high-salt wastewater, as detailed below: S1. High-mineralized water is fed into the pretreatment unit and the continuous flow resin hardening unit for resin hardening removal, and then filtered through the ultrafiltration unit to obtain ultrafiltration permeate. S2. The ultrafiltration permeate is treated by a multi-stage concentration unit to obtain product water while increasing the TDS in the wastewater. The concentrated water is then treated by an evaporation and crystallization unit to obtain sodium sulfate, sodium chloride and miscellaneous salts, respectively. S3. High-concentration sodium sulfate regenerated solution is fed into the continuous flow resin hardening unit. The regenerated waste liquid generated by resin regeneration is treated by the calcium sulfate reactor and softening and filtration unit. The produced water is recycled as the regenerated solution for continuous flow resin hardening. At the same time, sodium sulfate produced by freeze crystallization is used as the replenishment solution for the regenerated solution.

[0021] The invention is further characterized by: In S2: When the TDS in the raw water is ≤4500mg / L, the following treatment modes are selected: primary concentration, secondary concentration, tertiary concentration, evaporation unit, crystallization unit, freezing unit, sodium chloride evaporation and crystallization unit, and miscellaneous salt evaporation and crystallization unit. When the TDS in the raw water is greater than 4500 mg / L, the following treatment modes are selected: primary concentration, secondary concentration, evaporation unit, crystallization unit, freezing unit, sodium chloride evaporation and crystallization unit, and miscellaneous salt evaporation and crystallization unit. The main salt produced is sodium sulfate. When the raw water is a sodium sulfate system with a sulfate to chloride ratio of 40 or greater, the following treatment mode can be selected: primary concentration, secondary concentration, tertiary concentration, evaporation unit, crystallization unit, and mixed salt evaporation and crystallization unit; or the following treatment mode can be selected: primary concentration, secondary concentration, evaporation unit, crystallization unit, and mixed salt evaporation and crystallization unit. When the raw water is a sodium sulfate and sodium chloride system with sulfate and chloride ions in equal proportions or in a ratio of less than 40, the following treatment mode can be selected: primary concentration, secondary concentration, tertiary concentration, evaporation unit, crystallization unit, freezing unit, sodium chloride evaporation and crystallization unit, and mixed salt evaporation and crystallization unit; or the following treatment mode can be selected: primary concentration, secondary concentration, evaporation unit, crystallization unit, freezing unit, sodium chloride evaporation and crystallization unit, and mixed salt evaporation and crystallization unit.

[0022] The beneficial effects of this invention are: (1) The system for treating high-salt wastewater by hardening removal-circulating regeneration coupled membrane concentration of the present invention adopts a continuous flow resin hardening removal unit process, which can reduce the total hardness of high-mineralization wastewater from 1000mg / L to below 20mg / L, significantly improving the hardening removal efficiency and solving the problem of insufficient efficiency of ion exchange bed combination in the prior art; at the same time, because the turbidity and hardness of the water produced by the continuous flow resin hardening removal unit are low, the flux of the subsequent membrane device can be further increased, thereby reducing the number of membrane elements and devices, reducing the footprint, and reducing energy consumption and investment. (2) The present invention provides a system for treating high-salt wastewater by hard-circulation regeneration coupled membrane concentration. The regenerated waste liquid generates calcium sulfate precipitate through a calcium sulfate reactor, realizing the resource utilization of calcium sulfate and significantly reducing the amount of softened sludge. In addition, the reduction in the amount of reagent added correspondingly reduces the "salt" load in the system, that is, reduces the evaporation and crystallization load. (3) The present invention provides a system for treating high-salt wastewater by hardening-circulation regeneration coupling membrane concentration. After calcium sulfate precipitate is produced from the regenerated waste liquid, the remaining hardness is further softened and filtered. The concentrated brine is used to regenerate the resin, i.e., brine circulation regeneration. There is no need to add acid and alkali reagents for resin regeneration in conventional processes, which effectively reduces reagent costs and operating costs. It also reduces the "salt" load caused by the amount of reagent added, and the subsequent evaporation and crystallization load is effectively reduced. Attached Figure Description

[0023] Figure 1 This is the first system of the present invention for treating high-salt wastewater by removing hard-circulating regeneration coupled membrane concentration. Figure 2 This is the second system of the present invention for treating high-salt wastewater by removing hardening-circulating regeneration coupled membrane concentration; Figure 3 This is the third system of the present invention for treating high-salt wastewater by removing hardening-circulating regeneration coupled membrane concentration; Figure 4 This is the fourth system of the present invention for treating high-salt wastewater by removing hardness and recycling coupled membrane concentration.

[0024] In the diagram, 1. Pretreatment unit, 2. Continuous flow resin hardening unit, 3. Ultrafiltration unit, 4. Primary concentration unit, 5. Secondary concentration unit, 6. Hardening and desiliconizing filtration unit, 7. Tertiary concentration unit, 8. Evaporation unit, 9. Crystallization unit, 10. Freeze crystallization unit, 11. Sodium chloride evaporation and crystallization unit, 12. Miscellaneous salt evaporation and crystallization unit, 13. Calcium sulfate reactor, 14. Softening and filtration unit. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0026] This invention relates to a system for treating high-salinity wastewater using a hard-cycle regeneration coupled membrane for concentration, such as... Figure 1 As shown, the system includes a pretreatment unit 1, which is connected to a continuous flow resin hardening removal unit 2. The continuous flow resin hardening removal unit 2 is connected to an ultrafiltration unit 3. The ultrafiltration device further removes suspended solids and lost resin from the water, ensuring the long-term stable operation of the subsequent concentration unit. The ultrafiltration unit 3 is connected to a multi-stage concentration unit and a product water output pipe. The multi-stage concentration unit is connected to an evaporation and crystallization treatment unit. The ultrafiltration product water undergoes multi-stage concentration treatment (example: primary concentration, secondary concentration, hardening and silica removal filtration unit, tertiary concentration) to obtain product water while increasing the TDS in the wastewater, reducing the scale of subsequent evaporation, and improving system efficiency. It also includes a brine internal circulation regeneration unit, which is connected to the continuous flow resin hardening unit 2 and the evaporation crystallization treatment unit.

[0027] Furthermore, the continuous flow resin hardening unit 2 includes one resin exchange tower, two resin regeneration towers, and two resin cleaning towers, arranged in the following order: resin exchange tower, first resin regeneration tower, second resin regeneration tower, first resin cleaning tower, and second resin cleaning tower, arranged sequentially. The resin exchange tower is connected to the pretreatment unit 1, and the resin exchange tower is connected to the ultrafiltration unit 3.

[0028] Furthermore, the multi-stage concentration unit includes a primary concentration unit 4 connected to the ultrafiltration unit 3, a secondary concentration unit 5 connected to the primary concentration unit 4, a hardening and silica removal filtration unit 6 connected to the secondary concentration unit 5, a tertiary concentration unit 7 connected to the hardening and silica removal filtration unit 6, and an evaporation and crystallization treatment unit connected to the tertiary concentration unit 7. The primary concentration unit 4, the secondary concentration unit 5, and the tertiary concentration unit 7 are all connected to the product water output pipe through pipelines. Or, such as Figure 2 As shown, the multi-stage concentration unit includes a primary concentration unit 4 connected to the ultrafiltration unit 3, a secondary concentration unit 5 connected to the primary concentration unit 4, a hardening and silicon removal filtration unit 6 connected to the secondary concentration unit 5, and an evaporation and crystallization treatment unit connected to the hardening and silicon removal filtration unit 6. Both the primary concentration unit 4 and the secondary concentration unit 5 are connected to the product water output pipe through pipelines.

[0029] Furthermore, the multi-stage concentration unit adopts a combination of different devices such as reverse osmosis, nanofiltration, and electrodialysis. In this invention, the first-stage concentration unit 4 is reverse osmosis, nanofiltration, or electrodialysis, the second-stage concentration unit 5 is reverse osmosis or nanofiltration, and the third-stage concentration is reverse osmosis or nanofiltration, etc.

[0030] Furthermore, the hardening and desiliconizing filtration unit 6 includes any combination of treatment units such as a high-density pool-sand filtration-ultrafiltration unit, a high-density pool-ultrafiltration unit, or a reaction pool-tubular microfiltration or membrane softening unit.

[0031] Furthermore, the evaporation crystallization treatment unit includes an evaporation unit 8, which is connected to a three-stage concentration unit 7 or a hardening and desiliconizing filtration unit 6. The evaporation unit 8 is connected to a crystallization unit 9, which is connected to a freezing crystallization unit 10. The freezing crystallization unit 10 is connected to a sodium chloride evaporation crystallization unit 11. The freezing crystallization unit 10 is also connected to the pipeline between the evaporation unit 8 and the crystallization unit 9 through a pipeline. The freezing crystallization unit 10 is also connected to a brine internal circulation regeneration unit through a pipeline. The sodium chloride evaporation crystallization unit 11 is connected to a mixed salt evaporation crystallization unit 12. Or, such as Figure 4 As shown, the evaporation crystallization treatment unit includes an evaporation unit 8, which is connected to a three-stage concentration unit 7 or a hardening and silicon removal filtration unit 6. The evaporation unit 8 is connected to a crystallization unit 9, which is connected to a mixed salt evaporation crystallization unit 12. The crystallization unit 9 is also connected to a brine internal circulation regeneration unit through a pipeline.

[0032] Furthermore, the brine internal circulation regeneration unit includes a calcium sulfate reactor 13 connected to the continuous flow resin hardening unit 2. The calcium sulfate reactor 13 is also connected to a softening and filtration unit 14. The softening and filtration unit 14 is also connected to the continuous flow resin hardening unit 2 via a pipe. The pipe output from the crystallization unit 9 or the freeze crystallization unit 10 connects the pipe between the continuous flow resin hardening unit 2 and the softening and filtration unit 14.

[0033] The regeneration wastewater generated by the continuous flow resin is a high-concentration sulfate solution with high calcium and magnesium hardness, and is a calcium sulfate saturated solution. The regeneration wastewater generated by the continuous flow resin regeneration is treated by the calcium sulfate reactor 13 to obtain calcium sulfate product, realizing the resource utilization of brine. The permeate from the calcium sulfate reactor 13 is treated by the softening and filtration unit 14 to soften all the remaining calcium hardness and untreated magnesium hardness. The permeate with high salt content and low hardness is recycled as the regeneration liquid of the continuous flow resin, realizing water saving and consumption reduction in water treatment. The sodium sulfate solution generated by evaporation and crystallization is periodically used to replenish the regeneration liquid to maintain its salt concentration.

[0034] The recycled waste liquid enters the calcium sulfate reactor 13 for treatment. The calcium sulfate reactor 13 includes reaction devices such as a high-density tank, a mechanically accelerated clarification tank, and a calcium sulfate induced crystallizer, which produce calcium sulfate precipitate. The calcium sulfate precipitate is concentrated and filtered before being used as gypsum, thus realizing the resource utilization of sludge. Some calcium ions leave the system as calcium sulfate, eliminating the need for double alkali softening treatment and further reducing the reagent costs and operating expenses of subsequent softening processes.

[0035] The water produced by the calcium sulfate reactor 13 is sent to the softening and filtration unit 14, where the remaining calcium ions and unremoved magnesium ions are significantly removed using a dual alkali method. The softening and filtration unit 14 adopts any of the following treatment units: high-density tank-sand filtration-ultrafiltration unit, high-density tank-ultrafiltration unit, reaction tank-tubular microfiltration unit, or membrane softening unit. The salt concentration of the permeate (total hardness less than 200-400 mg / L) is slightly reduced. The high-purity, high-concentration sodium sulfate solution produced by the freeze crystallization unit 10 or the crystallization unit 9 is added to the permeate of the softening and filtration unit 14 to maintain the salt concentration of the continuous flow resin regeneration solution, thereby realizing the internal regeneration and recycling of brine.

[0036] The main workflow is as follows: Pretreatment unit 1 effectively removes suspended solids from the raw water. The permeate from pretreatment unit 1 passes through continuous flow resin hardening unit 2 to remove calcium and magnesium ions. The permeate from continuous flow resin hardening passes through ultrafiltration unit 3 to further intercept small particulate suspended solids, colloids, etc., and then passes through primary concentration unit 4 and secondary concentration unit 5. The concentrated water passes through hardening and silica removal filtration unit 6, and its permeate passes through tertiary concentration unit 7. Finally, the fresh water is reused, while the concentrated brine is sent to evaporation unit 8 for further concentration. The evaporated concentrated water is evaporated and crystallized to produce sodium sulfate as a by-product. The crystallization mother liquor is further reduced by freezing crystallization treatment. The crystallization mother liquor is sent to sodium chloride evaporation and crystallization unit 11 to produce sodium chloride as a by-product. The sodium chloride evaporation and crystallization mother liquor is evaporated and crystallized by miscellaneous salt evaporation and crystallization unit 12 to produce a small amount of miscellaneous salts.

[0037] The continuous flow resin hardening unit 2 uses brine internal circulation regeneration. That is, sodium sulfate regeneration solution is prepared for the first time to regenerate saturated resin. The generated regeneration waste liquid is processed by calcium sulfate reactor 13 to generate calcium sulfate. The remaining hardness in the regeneration waste liquid is treated by softening and filtration unit 14. The hardness is controlled to a low level (less than 100-150 mg / L) and the resulting product water is used as the regeneration solution for continuous flow resin hardening. At the same time, sodium sulfate produced by freeze crystallization is used as the replenishment solution for the regeneration solution.

[0038] The high-salinity water treatment method of the present invention uses the above-mentioned hardening-regeneration coupled membrane concentration system for treating high-salinity wastewater, as detailed below: S1. High-mineralized water is input into pretreatment unit 1 and continuous flow resin hardening unit 2 for resin hardening removal, and then filtered through ultrafiltration unit 3 to obtain ultrafiltration permeate. Continuous flow resin hardening is used to efficiently and stably reduce the hardness of wastewater.

[0039] Specifically, the continuous flow resin hardening system adopts a multi-tower moving bed operation mode, including 3, 4, or 5 towers. Generally, tower 1 is a resin exchange tower, tower 2 is a resin regeneration tower, and tower 3 is a resin cleaning tower; after modification, tower 1 is a resin exchange tower, towers 2 and 3 are resin regeneration towers, and tower 4 or 5 is a resin cleaning tower; by using a multi-tower string arrangement, the resin moves within each tower, improving the efficiency of resin regeneration and utilization; The feed water of the first tower exchanges calcium and magnesium hardness (e.g., feed water hardness 1000 mg / L, product water hardness less than 10 mg / L). After running automatically for 40-60 minutes, the bottom resin is transferred to the subsequent regeneration tower and washing tower. This process is repeated continuously. The resin is periodically regenerated using a concentrated sodium sulfate solution (10-15% concentration) circulating within the system to ensure its exchange capacity.

[0040] S2. The ultrafiltration permeate is treated by a multi-stage concentration unit to obtain product water while increasing the TDS in the wastewater. The concentrated water is then treated by an evaporation and crystallization unit to obtain sodium sulfate, sodium chloride and miscellaneous salts, realizing the resource utilization of water and salt, generating a small amount of miscellaneous salts, and reducing the cost of solid waste disposal. First, the ultrafiltration unit 3 further removes suspended solids and colloids from the water, effectively ensuring the processing efficiency of the subsequent concentration unit. After the incoming water undergoes pretreatment unit 1 and continuous flow resin hardening unit 2 for hardening treatment, the suspended solids index of the incoming water is relatively low, allowing for a wider selection of ultrafiltration membrane flux. For example, if the membrane flux is increased to 50-60 LMH, the investment can be further reduced while effectively ensuring water quality.

[0041] Secondly, the ultrafiltration permeate undergoes multi-stage concentration treatment, such as... Figure 1 First-stage concentration - Second-stage concentration - Hard and silicon removal filtration unit - Third-stage concentration, or Figure 2 The system consists of a primary concentration stage, a secondary concentration stage, and a hardness and silica removal filtration unit. Specific usage methods may vary depending on the situation, as detailed below: When the TDS in the raw water is ≤4500 mg / L, select Figure 1 The process involves primary concentration, secondary concentration, tertiary concentration, evaporation unit, crystallization unit, freezing unit, sodium chloride evaporation and crystallization unit, and miscellaneous salt evaporation and crystallization unit. When the TDS in the raw water is >4500 mg / L, select Figure 2 The process involves primary concentration, secondary concentration, evaporation unit, crystallization unit, freezing unit, sodium chloride evaporation and crystallization unit, and miscellaneous salt evaporation and crystallization unit. The main salt produced is sodium sulfate.

[0042] After the incoming water is dehardened by the continuous flow resin, the multi-stage concentration treatment targets the low hardness, and the membrane concentration can select a higher concentration ratio, such as 4 times or 5 times the concentration ratio. After one or two stages of concentration, the calcium and magnesium hardness and unremoved silicon in the wastewater further increase. In order to ensure the stable operation of the subsequent concentration or evaporation crystallization system, a hardness and silicon removal filtration unit is used to further remove the above-mentioned scale-forming ions such as calcium, magnesium and silicon. The concentrated brine after multiple stages of concentration is sent to an evaporation and crystallization unit for further processing to obtain byproducts sodium sulfate, sodium chloride, and a small amount of other salts. The selection criteria for the evaporation and crystallization unit are as follows: When the raw water is a sodium sulfate system with a sufficiently high sulfate to chloride ratio (greater than or equal to 40), choose... Figure 3 The process can be carried out using a combination of primary concentration, secondary concentration, tertiary concentration, evaporation unit, crystallization unit, and mixed salt evaporation and crystallization unit; or alternatively, the following can be selected: Figure 4 The process involves primary concentration, secondary concentration, evaporation unit, crystallization unit, and miscellaneous salt evaporation and crystallization unit. When the raw water is a sodium sulfate / sodium chloride system with equal or small ratios of sulfate and chloride (less than 40%), choose... Figure 1 The process can be carried out using a combination of primary concentration, secondary concentration, tertiary concentration, evaporation unit, crystallization unit, freezing unit, sodium chloride evaporation and crystallization unit, and miscellaneous salt evaporation and crystallization unit; or alternatively, the following can be selected: Figure 2 The process involves primary concentration, secondary concentration, evaporation unit, crystallization unit, freezing unit, sodium chloride evaporation and crystallization unit, and miscellaneous salt evaporation and crystallization unit.

[0043] S3. High-purity, high-concentration sodium sulfate solution is used as the regenerator for the continuous flow resin. The regenerator required for the first operation of the system is prepared by dissolving sodium sulfate product salt produced by the surrounding water treatment project or purchased anhydrous sodium sulfate. The high-purity, high-concentration sodium sulfate regenerator is input into the continuous flow resin hardening unit 2. The regeneration waste liquid generated by the resin regeneration is treated by the calcium sulfate reactor 13 and the softening and filtration unit 14. The produced water is recycled as the regenerator for the continuous flow resin hardening. At the same time, sodium sulfate produced by freeze crystallization is used as the replenishment liquid for the regenerator.

[0044] Continuous flow resin exchange removes calcium and magnesium hardness from water. After saturation, the saturated resin is regenerated using a high-purity, high-concentration sodium sulfate solution (brine circulation regeneration), replacing the conventional acid-alkali regeneration method, thus achieving low-carbon and economical water treatment.

[0045] Figure 1 , Figure 2 The high-purity sodium sulfate thawed solution produced by freeze crystallization 10 is used as a supplement to the regeneration solution of the continuous flow resin. Figure 3 , Figure 4 The high-purity sodium sulfate solution produced by crystallization unit 9 is used as a supplement to the continuous flow resin regeneration solution, realizing the internal circulation of brine from waste liquid to treatment to regeneration solution, eliminating the consumption of acid and alkali reagents required for resin regeneration in conventional processes.

[0046] Example 1 This embodiment describes a system for treating high-salinity wastewater using a hard-cycle regeneration coupled membrane concentration method, such as... Figure 1 As shown, the system includes a pretreatment unit 1, which is connected to a continuous flow resin hardening removal unit 2. The continuous flow resin hardening removal unit 2 is connected to an ultrafiltration unit 3. The ultrafiltration device further removes suspended solids and lost resin from the water, ensuring the long-term stable operation of the subsequent concentration unit. The ultrafiltration unit 3 is connected to a multi-stage concentration unit and a product water output pipe. The multi-stage concentration unit is connected to an evaporation and crystallization treatment unit. The ultrafiltration product water undergoes multi-stage concentration treatment (example: primary concentration, secondary concentration, hardening and silica removal filtration unit, tertiary concentration) to obtain product water while increasing the TDS in the wastewater, reducing the scale of subsequent evaporation, and improving system efficiency. It also includes a brine internal circulation regeneration unit, which is connected to the continuous flow resin hardening unit 2 and the evaporation crystallization treatment unit.

[0047] Example 2 Based on Example 1, this embodiment further includes a continuous flow resin hardening unit 2 comprising one resin exchange tower, two resin regeneration towers, and two resin cleaning towers, arranged in the following order: resin exchange tower, first resin regeneration tower, second resin regeneration tower, first resin cleaning tower, and second resin cleaning tower, arranged sequentially. The resin exchange tower is connected to the pretreatment unit 1 and the resin exchange tower is connected to the ultrafiltration unit 3.

[0048] Furthermore, the multi-stage concentration unit includes a primary concentration unit 4 connected to the ultrafiltration unit 3, a secondary concentration unit 5 connected to the primary concentration unit 4, a hardening and silica removal filtration unit 6 connected to the secondary concentration unit 5, a tertiary concentration unit 7 connected to the hardening and silica removal filtration unit 6, and an evaporation and crystallization treatment unit connected to the tertiary concentration unit 7. The primary concentration unit 4, the secondary concentration unit 5, and the tertiary concentration unit 7 are all connected to the product water output pipe through pipelines. Or, such as Figure 2 As shown, the multi-stage concentration unit includes a primary concentration unit 4 connected to the ultrafiltration unit 3, a secondary concentration unit 5 connected to the primary concentration unit 4, a hardening and silicon removal filtration unit 6 connected to the secondary concentration unit 5, and an evaporation and crystallization treatment unit connected to the hardening and silicon removal filtration unit 6. Both the primary concentration unit 4 and the secondary concentration unit 5 are connected to the product water output pipe through pipelines.

[0049] Example 3 Based on Example 2, this embodiment further adopts a combination of different devices such as reverse osmosis, nanofiltration, and electrodialysis in the multi-stage concentration unit. In this invention, the first-stage concentration unit 4 is reverse osmosis, nanofiltration, or electrodialysis, the second-stage concentration unit 5 is reverse osmosis or nanofiltration, and the third-stage concentration is reverse osmosis or nanofiltration, etc.

[0050] Example 4 Based on Example 3, this embodiment further includes any combination of processing units such as a high-density pool-sand filter-ultrafiltration unit, a high-density pool-ultrafiltration unit, or a reaction pool-tubular microfiltration or membrane softening unit.

[0051] Example 5 Based on embodiment 1, this embodiment further includes an evaporation crystallization processing unit comprising an evaporation unit 8, which is connected to a three-stage concentration unit 7 or a hardening and silicon removal filtration unit 6. The evaporation unit 8 is connected to a crystallization unit 9, which is connected to a freezing crystallization unit 10. The freezing crystallization unit 10 is connected to a sodium chloride evaporation crystallization unit 11. The freezing crystallization unit 10 is also connected to a pipe between the evaporation unit 8 and the crystallization unit 9. The freezing crystallization unit 10 is also connected to a brine internal circulation regeneration unit via a pipe. The sodium chloride evaporation crystallization unit 11 is connected to a mixed salt evaporation crystallization unit 12. Or, such as Figure 4 As shown, the evaporation crystallization treatment unit includes an evaporation unit 8, which is connected to a three-stage concentration unit 7 or a hardening and silicon removal filtration unit 6. The evaporation unit 8 is connected to a crystallization unit 9, which is connected to a mixed salt evaporation crystallization unit 12. The crystallization unit 9 is also connected to a brine internal circulation regeneration unit through a pipeline.

[0052] Example 6 Based on Example 1, this embodiment further includes a calcium sulfate reactor 13 connected to the continuous flow resin hardening unit 2. The calcium sulfate reactor 13 is also connected to a softening and filtration unit 14. The softening and filtration unit 14 is also connected to the continuous flow resin hardening unit 2 via a pipe. The pipe output from the crystallization unit 9 or the freeze crystallization unit 10 connects the pipe between the continuous flow resin hardening unit 2 and the softening and filtration unit 14.

[0053] The regeneration wastewater generated by the continuous flow resin is a high-concentration sulfate solution with high calcium and magnesium hardness, and is a calcium sulfate saturated solution. The regeneration wastewater generated by the continuous flow resin regeneration is treated by the calcium sulfate reactor 13 to obtain calcium sulfate product, realizing the resource utilization of brine. The permeate from the calcium sulfate reactor 13 is treated by the softening and filtration unit 14 to soften all the remaining calcium hardness and untreated magnesium hardness. The permeate with high salt content and low hardness is recycled as the regeneration liquid of the continuous flow resin, realizing water saving and consumption reduction in water treatment. The sodium sulfate solution generated by evaporation and crystallization is periodically used to replenish the regeneration liquid to maintain its salt concentration.

[0054] The recycled waste liquid enters the calcium sulfate reactor 13 for treatment. The calcium sulfate reactor 13 includes reaction devices such as a high-density tank, a mechanically accelerated clarification tank, and a calcium sulfate induced crystallizer, which produce calcium sulfate precipitate. The calcium sulfate precipitate is concentrated and filtered before being used as gypsum, thus realizing the resource utilization of sludge. Some calcium ions leave the system as calcium sulfate, eliminating the need for double alkali softening treatment and further reducing the reagent costs and operating expenses of subsequent softening processes.

[0055] The water produced by the calcium sulfate reactor 13 is sent to the softening and filtration unit 14, where the remaining calcium ions and unremoved magnesium ions are significantly removed using a dual alkali method. The softening and filtration unit 14 can be any of the following treatment units: high-density tank-sand filtration-ultrafiltration unit, high-density tank-ultrafiltration unit, reaction tank-tubular microfiltration unit, or membrane softening unit.

[0056] Example 7 The high-mineralization water treatment method of this embodiment is as follows: S1. High-mineralized water is input into pretreatment unit 1 and continuous flow resin hardening unit 2 for resin hardening removal, and then filtered through ultrafiltration unit 3 to obtain ultrafiltration permeate. Continuous flow resin hardening is used to efficiently and stably reduce the hardness of wastewater.

[0057] S2. The ultrafiltration permeate is treated by a multi-stage concentration unit to obtain product water while increasing the TDS in the wastewater. The concentrated water is then treated by an evaporation and crystallization unit to obtain sodium sulfate, sodium chloride and miscellaneous salts, realizing the resource utilization of water and salt, generating a small amount of miscellaneous salts, and reducing the cost of solid waste disposal. First, the ultrafiltration unit 3 further removes suspended solids and colloids from the water, effectively ensuring the processing efficiency of the subsequent concentration unit. After the incoming water undergoes pretreatment unit 1 and continuous flow resin hardening unit 2 for hardening treatment, the suspended solids index of the incoming water is relatively low, allowing for a wider selection of ultrafiltration membrane flux. For example, if the membrane flux is increased to 50-60 LMH, the investment can be further reduced while effectively ensuring water quality.

[0058] Secondly, the ultrafiltration permeate undergoes multi-stage concentration treatment, such as... Figure 1 First-stage concentration - Second-stage concentration - Hard and silicon removal filtration unit - Third-stage concentration, or Figure 2 The system consists of a primary concentration stage, a secondary concentration stage, and a hardness and silica removal filter unit. Specific usage instructions should be adjusted according to the emergency situation, as follows: When the TDS in the raw water is ≤4500 mg / L, select Figure 1 The process involves primary concentration, secondary concentration, tertiary concentration, evaporation unit, crystallization unit, freezing unit, sodium chloride evaporation and crystallization unit, and miscellaneous salt evaporation and crystallization unit. When the TDS in the raw water is >4500 mg / L, select Figure 2 The process involves primary concentration, secondary concentration, evaporation unit, crystallization unit, freezing unit, sodium chloride evaporation and crystallization unit, and miscellaneous salt evaporation and crystallization unit. The main salt produced is sodium sulfate.

[0059] After the incoming water is dehardened by the continuous flow resin, the multi-stage concentration treatment targets the low hardness, and the membrane concentration can select a higher concentration ratio, such as 4 times or 5 times the concentration ratio. After one or two stages of concentration, the calcium and magnesium hardness and unremoved silicon in the wastewater further increase. In order to ensure the stable operation of the subsequent concentration or evaporation crystallization system, a hardness and silicon removal filtration unit is used to further remove the above-mentioned scale-forming ions such as calcium, magnesium and silicon. The concentrated brine after multiple stages of concentration is sent to an evaporation and crystallization unit for further processing to obtain byproducts sodium sulfate, sodium chloride, and a small amount of other salts. The selection criteria for the evaporation and crystallization unit are as follows: When the raw water is a sodium sulfate system with a sufficiently high sulfate to chloride ratio (greater than or equal to 40), choose... Figure 3 The process can be carried out using a combination of primary concentration, secondary concentration, tertiary concentration, evaporation unit, crystallization unit, and mixed salt evaporation and crystallization unit; or alternatively, the following can be selected: Figure 4 The process involves primary concentration, secondary concentration, evaporation unit, crystallization unit, and miscellaneous salt evaporation and crystallization unit. When the raw water is a sodium sulfate / sodium chloride system with equal or small ratios of sulfate and chloride (less than 40%), choose... Figure 1 The process can be carried out using a combination of primary concentration, secondary concentration, tertiary concentration, evaporation unit, crystallization unit, freezing unit, sodium chloride evaporation and crystallization unit, and miscellaneous salt evaporation and crystallization unit; or alternatively, the following can be selected: Figure 2 The process involves primary concentration, secondary concentration, evaporation unit, crystallization unit, freezing unit, sodium chloride evaporation and crystallization unit, and miscellaneous salt evaporation and crystallization unit.

[0060] S3. High-purity, high-concentration sodium sulfate solution is used as the regenerator for the continuous flow resin. The regenerator required for the first operation of the system is prepared by dissolving sodium sulfate product salt produced by the surrounding water treatment project or purchased anhydrous sodium sulfate. The high-purity, high-concentration sodium sulfate regenerator is input into the continuous flow resin hardening unit 2. The regeneration waste liquid generated by the resin regeneration is treated by the calcium sulfate reactor 13 and the softening and filtration unit 14. The produced water is recycled as the regenerator for the continuous flow resin hardening. At the same time, sodium sulfate produced by freeze crystallization is used as the replenishment liquid for the regenerator.

[0061] Continuous flow resin exchange removes calcium and magnesium hardness from water. After saturation, the saturated resin is regenerated using a high-purity, high-concentration sodium sulfate solution (brine circulation regeneration), replacing the conventional acid-alkali regeneration method, thus achieving low-carbon and economical water treatment.

Claims

1. A system for treating high-salinity wastewater by removing hard-phase-recycle-regeneration coupled membrane concentration, characterized in that, It includes a pretreatment unit (1), which is connected to a continuous flow resin hardening unit (2), which is connected to an ultrafiltration unit (3), which is connected to a multi-stage concentration unit and a product water output pipe, and the multi-stage concentration unit is connected to an evaporation crystallization treatment unit. It also includes a brine internal circulation regeneration unit, which is connected to the continuous flow resin hardening unit (2) and the evaporation crystallization treatment unit.

2. The system for treating high-salinity wastewater by removing hardening-circulating regeneration coupled membrane concentration according to claim 1, characterized in that, The continuous flow resin hardening unit (2) includes one resin exchange tower, two resin regeneration towers and two resin cleaning towers, arranged in the following order: resin exchange tower, first resin regeneration tower, second resin regeneration tower, first resin cleaning tower and second resin cleaning tower, arranged in sequence. The resin exchange tower is connected to the pretreatment unit (1) and the resin exchange tower is connected to the ultrafiltration unit (3).

3. The system for treating high-salinity wastewater by removing hardening-circulating regeneration coupled membrane concentration according to claim 2, characterized in that, The multi-stage concentration unit includes a primary concentration unit (4) connected to the ultrafiltration unit (3), a secondary concentration unit (5) connected to the primary concentration unit (4), a hardening and silicon removal filtration unit (6) connected to the secondary concentration unit (5), a tertiary concentration unit (7) connected to the hardening and silicon removal filtration unit (6), and an evaporation and crystallization treatment unit connected to the tertiary concentration unit (7). The primary concentration unit (4), the secondary concentration unit (5), and the tertiary concentration unit (7) are all connected to the product water output pipe through pipelines. Alternatively, the multi-stage concentration unit includes a primary concentration unit (4) connected to the ultrafiltration unit (3), the primary concentration unit (4) is connected to a secondary concentration unit (5), the secondary concentration unit (5) is connected to a hardening and desiliconizing filtration unit (6), the hardening and desiliconizing filtration unit (6) is connected to an evaporation and crystallization treatment unit, and the primary concentration unit (4) and the secondary concentration unit (5) are both connected to the product water output pipe through pipelines.

4. The system for treating high-salinity wastewater by removing hardening-circulating regeneration coupled membrane concentration according to claim 3, characterized in that, The primary concentration unit (4) includes a reverse osmosis device, a nanofiltration device, or an electrodialysis device; the secondary concentration unit (5) includes a reverse osmosis device or a nanofiltration device; and the tertiary concentration unit (7) includes a reverse osmosis device or a nanofiltration device.

5. The system for treating high-salinity wastewater by removing hardening-circulating regeneration coupled membrane concentration according to claim 4, characterized in that, The hardness and silicon removal filtration unit (6) includes any combination of processing units such as high-density pool-sand filtration-ultrafiltration unit, high-density pool-ultrafiltration unit, or reaction pool-tubular microfiltration or membrane softening unit.

6. The system for treating high-salinity wastewater by removing hardening-circulating regeneration coupled membrane concentration according to claim 1, characterized in that, The evaporation crystallization processing unit includes an evaporation unit (8), which is connected to a three-stage concentration unit (7) or a hardening and silicon removal filtration unit (6). The evaporation unit (8) is connected to a crystallization unit (9), which is connected to a freezing crystallization unit (10). The freezing crystallization unit (10) is connected to a sodium chloride evaporation crystallization unit (11). The freezing crystallization unit (10) is also connected to a pipeline between the evaporation unit (8) and the crystallization unit (9) through a pipeline. The freezing crystallization unit (10) is also connected to a brine internal circulation regeneration unit through a pipeline. The sodium chloride evaporation crystallization unit (11) is connected to a miscellaneous salt evaporation crystallization unit (12). Alternatively, the evaporation crystallization processing unit includes an evaporation unit (8), which is connected to a three-stage concentration unit (7) or a hardening and silicon removal filtration unit (6). The evaporation unit (8) is connected to a crystallization unit (9), which is connected to a mixed salt evaporation crystallization unit (12). The crystallization unit (9) is also connected to a brine internal circulation regeneration unit via a pipeline.

7. The system for treating high-salinity wastewater by removing hardening-circulating regeneration coupled membrane concentration according to claim 6, characterized in that, The brine internal circulation regeneration unit includes a calcium sulfate reactor (13) connected to the continuous flow resin hardening unit (2). The calcium sulfate reactor (13) is also connected to a softening and filtration unit (14). The softening and filtration unit (14) is also connected to the continuous flow resin hardening unit (2) through a pipe. The pipe output from the crystallization unit (9) or the freeze crystallization unit (10) connects the pipe between the continuous flow resin hardening unit (2) and the softening and filtration unit (14).

8. The system for treating high-salinity wastewater by removing hardening-circulating regeneration coupled membrane concentration according to claim 7, characterized in that, The calcium sulfate reactor (13) includes a high-density tank, a mechanically accelerated clarification tank, a calcium sulfate induced crystallizer, and other reaction devices; The softening and filtration unit (14) includes any of the following processing units: high-density pool-sand filtration-ultrafiltration unit, high-density pool-ultrafiltration unit, or reaction pool-tubular microfiltration or membrane softening unit.

9. A method for treating high-mineralization water, characterized in that, The system for treating high-salinity wastewater using the hard-recycle-regeneration coupled membrane concentration method as described in claim 1 is as follows: S1. High-mineralized water is input into the pretreatment unit (1) and the continuous flow resin hardening unit (2) for resin hardening, and then filtered through the ultrafiltration unit (3) to obtain ultrafiltration permeate. S2. The ultrafiltration permeate is treated by a multi-stage concentration unit to obtain product water while increasing the TDS in the wastewater. The concentrated water is then treated by an evaporation and crystallization unit to obtain sodium sulfate, sodium chloride and miscellaneous salts, respectively. S3. High-concentration sodium sulfate regenerated liquid is input into the continuous flow resin hardening unit (2). The regenerated waste liquid generated by resin regeneration is treated by the calcium sulfate reactor (13) and the softening and filtration unit (14). The produced water is recycled as the regenerated liquid for continuous flow resin hardening. At the same time, sodium sulfate produced by freeze crystallization is used as the replenishing liquid for the regenerated liquid.

10. The high-mineralization water treatment method according to claim 9, characterized in that, In S2: When the TDS in the raw water is ≤4500mg / L, the following treatment modes are selected: primary concentration, secondary concentration, tertiary concentration, evaporation unit, crystallization unit, freezing unit, sodium chloride evaporation and crystallization unit, and miscellaneous salt evaporation and crystallization unit. When the TDS in the raw water is greater than 4500 mg / L, the following treatment modes are selected: primary concentration, secondary concentration, evaporation unit, crystallization unit, freezing unit, sodium chloride evaporation and crystallization unit, and miscellaneous salt evaporation and crystallization unit. The main salt produced is sodium sulfate. When the raw water is a sodium sulfate system with a sulfate to chloride ratio of 40 or greater, the following treatment modes are selected: primary concentration, secondary concentration, tertiary concentration, evaporation unit, crystallization unit, and mixed salt evaporation and crystallization unit. Alternatively, a process can be adopted that combines primary concentration, secondary concentration, evaporation unit, crystallization unit, and mixed salt evaporation and crystallization unit. When the raw water is a sodium sulfate and sodium chloride system with sulfate and chloride ions in equal proportions or in a ratio of less than 40, the following treatment mode can be selected: primary concentration, secondary concentration, tertiary concentration, evaporation unit, crystallization unit, freezing unit, sodium chloride evaporation and crystallization unit, and mixed salt evaporation and crystallization unit; or the following treatment mode can be selected: primary concentration, secondary concentration, evaporation unit, crystallization unit, freezing unit, sodium chloride evaporation and crystallization unit, and mixed salt evaporation and crystallization unit.

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