High-salt industrial wastewater treatment device

Abstract

The utility model relates to the technical field of high-salinity wastewater treatment, in particular to a high-salinity industrial wastewater treatment device which comprises an adjusting tank, the water outlet end of the adjusting tank is connected with the water inlet end of a hardness removal tank through a pipeline A, and the water outlet end of the hardness removal tank is connected with the water inlet end of a reaction sedimentation tank through a pipeline B; the water outlet end of the reaction sedimentation tank is connected with the water inlet end of the multi-medium filter through a pipeline C, the multi-medium filter is connected with the water inlet end of the multi-stage tandem reverse osmosis desalting system through a pipeline D, and the concentrated water outlet end of the multi-stage tandem reverse osmosis desalting system is connected with the water inlet end of the triple-effect multi-stage evaporator through a pipeline E; the concentrated liquid outlet end of the triple-effect multistage evaporator is connected with the water inlet end of the crystallizer through a pipeline F; wherein the pipeline A, the pipeline B, the pipeline C, the pipeline D, the pipeline E and the pipeline F are all provided with water pumps. According to the utility model, the service life of the membrane is prolonged, the energy consumption is reduced, and meanwhile, the recycling of salt can be realized.

Description

Technical Field

[0001] This utility model relates to the field of high-salinity wastewater treatment technology, specifically to a high-salinity industrial wastewater treatment device. Background Technology

[0002] High-salinity industrial wastewater refers to industrial wastewater with a salt content (calculated as sodium chloride) exceeding 1%, mainly originating from various industrial sectors such as chemical production processes, pharmaceuticals, electroplating and metal processing, petroleum refining, and food processing. This type of wastewater not only contains high concentrations of inorganic salts (such as NaCl and Na₂SO₄), but often also heavy metal ions, organic pollutants, and other toxic and harmful substances. Traditional methods for treating high-salinity wastewater mainly include dilution and discharge, deep well injection, and natural evaporation in evaporation ponds. However, these methods either fail to meet increasingly stringent environmental regulations or suffer from low treatment efficiency, large land area requirements, and high energy consumption.

[0003] In recent years, the combined application of membrane separation technology with evaporation crystallization technology has provided a new technical approach for the treatment of high-salinity wastewater. Membrane technologies, such as reverse osmosis, have advantages such as high efficiency, energy saving, and simple operation, and can effectively achieve wastewater concentration and volume reduction.

[0004] Reverse osmosis technology utilizes the principle of a semi-permeable membrane. Under pressure, water molecules are forced through the membrane, while salts and other impurities are retained, thus concentrating wastewater. Reverse osmosis membranes have a high rejection rate and can effectively remove salts and most organic matter from wastewater.

[0005] Evaporation crystallization technology can further treat concentrated high-salt wastewater, achieving salt recovery and water reuse. The evaporation crystallization process involves heating the wastewater to evaporate it, causing the salt to reach a supersaturated state, resulting in crystallization. The recovered salt can be reused as industrial raw materials, while the condensate produced during evaporation can be recycled, achieving water resource recycling.

[0006] However, existing membrane-evaporation coupling technology has the following technical problems:

[0007] Suspended solids, colloidal substances, and sparingly soluble salts in high-salinity wastewater easily cause membrane fouling. Suspended solids and colloidal substances form a filter cake layer on the membrane surface, hindering the passage of water molecules and leading to a decrease in membrane flux. Sparingly soluble salts, such as calcium carbonate and calcium sulfate, crystallize and precipitate on the membrane surface, forming a scale layer, further reducing membrane flux. Membrane fouling not only affects the stable operation of the system but also increases the frequency and cost of cleaning. Frequent cleaning shortens the membrane's lifespan and increases operating costs.

[0008] Traditional evaporation systems still suffer from high energy consumption when treating high-salinity wastewater. The evaporation process requires a significant amount of heat energy to heat and evaporate the wastewater, especially when the influent salt concentration is low. A large amount of water needs to be evaporated to reach the required salt concentration for crystallization, making the energy consumption even more pronounced. This high energy consumption not only increases treatment costs but also fails to meet energy conservation and emission reduction requirements.

[0009] Existing separation technologies are insufficient to effectively separate these salts, and the recovered salt often contains various impurities with low purity, failing to meet the requirements of industrial production and thus limiting the resource utilization of salts. Utility Model Content

[0010] In view of the technical problems of membrane fouling, high energy consumption and difficulty in salt recovery in the treatment of high-salt industrial wastewater, the present invention provides a high-salt industrial wastewater treatment device that extends the service life of the membrane, reduces energy consumption, and enables the resource-based reuse of salt.

[0011] The technical solution adopted in this utility model is as follows:

[0012] A high-salinity industrial wastewater treatment device includes an equalization tank. The outlet of the equalization tank is connected to the inlet of a hardening tank via pipe A. The outlet of the hardening tank is connected to the inlet of a reaction sedimentation tank via pipe B. The outlet of the reaction sedimentation tank is connected to the inlet of a multi-media filter via pipe C. The multi-media filter is connected to the inlet of a multi-stage series reverse osmosis desalination system via pipe D. The concentrate outlet of the multi-stage series reverse osmosis desalination system is connected to the inlet of a triple-effect multi-stage evaporator via pipe E. The concentrate outlet of the triple-effect multi-stage evaporator is connected to the inlet of a crystallizer via pipe F. Each of pipes A, B, C, D, E, and F is equipped with a water pump.

[0013] It should be further noted that the multi-media filter is filled with a layer of quartz sand and a layer of activated carbon from top to bottom.

[0014] It should be further noted that the particle size of the quartz sand in the quartz sand layer is 2~4mm, and the particle size of the activated carbon in the activated carbon layer is 1~2mm.

[0015] It should be further noted that the multi-stage series reverse osmosis desalination system includes a first-stage reverse osmosis unit and a second-stage reverse osmosis unit connected in series.

[0016] It should be further noted that this utility model also includes an intermediate water tank. The inlet of the intermediate water tank is connected to the product water outlet of the first-stage reverse osmosis device via pipe G. The inlet of the intermediate water tank is also connected to the product water outlet of the second-stage reverse osmosis device via pipe H.

[0017] It should be further noted that the condensate outlet of the triple-effect multi-stage evaporator is connected to the inlet of the intermediate water tank via pipe I.

[0018] It should be further noted that this utility model also includes a reclaimed water reverse osmosis desalination system, the inlet of which is connected to the outlet of the intermediate water tank via pipe J.

[0019] It should be further noted that this utility model also includes a centrifuge, the feed pipe of which is connected to the discharge end of the crystallizer via pipe K.

[0020] The functions of each component of this utility model are as follows:

[0021] Equalization Tank: As the starting unit of the entire treatment system, the equalization tank plays a role in regulating the quality and quantity of wastewater. High-salinity industrial wastewater first enters the equalization tank to homogenize the flow rate and quality, providing stable influent conditions for subsequent treatment units. The outlet of the equalization tank is connected to the inlet of the hardening removal tank via pipe A. A water pump is installed on pipe A to transport the wastewater from the equalization tank to the hardening removal tank.

[0022] The hardness removal tank's main function is to add sodium hydroxide and sodium carbonate to remove hardness substances such as calcium and magnesium ions from wastewater. These hardness substances can cause scaling and other problems during subsequent treatment, affecting the normal operation of the equipment and its treatment effect. The outlet of the hardness removal tank is connected to the inlet of the reaction sedimentation tank via pipe B. The water pump on pipe B transports the treated wastewater to the reaction sedimentation tank.

[0023] Reaction sedimentation tank: In the reaction sedimentation tank, wastewater reacts with chemical agents (flocculators), causing impurities in the wastewater to form precipitates through rapid mixing and flocculation. Through sedimentation, these precipitates are separated from the wastewater, removing colloidal substances and some heavy metal ions, controlling the effluent turbidity below 5 NTU, further purifying the wastewater. The effluent outlet of the reaction sedimentation tank is connected to the inlet of the multi-media filter via pipe C, and a pump on pipe C is responsible for transporting the wastewater.

[0024] Multi-media filter: Internally filled with two layers of filter media, from top to bottom: a quartz sand layer and an activated carbon layer. Quartz sand has excellent filtration properties, removing suspended solids and some colloidal substances from wastewater; activated carbon has a large specific surface area, capable of adsorbing organic matter and odors from wastewater. The multi-media filter further removes impurities from wastewater through physical filtration, improving water quality and ensuring that the filtered effluent SDI15 < 3, meeting the feed water requirements of subsequent reverse osmosis membrane elements. Its outlet is connected to the inlet of a multi-stage series reverse osmosis desalination system via pipe D, and a pump on pipe D delivers wastewater to this system.

[0025] A multi-stage series reverse osmosis desalination system consists of a primary reverse osmosis unit and a secondary reverse osmosis unit connected in series. Reverse osmosis is a highly efficient membrane separation technology that can effectively remove salt from wastewater. Connecting the two reverse osmosis units in series further improves the desalination effect. Furthermore, both the primary and secondary reverse osmosis units are equipped with online chemical cleaning devices that automatically trigger the cleaning program based on changes in transmembrane pressure difference (TMP), employing an alternating acid-alkali cleaning process to restore membrane flux and extend membrane lifespan. The concentrated water outlet of this multi-stage series reverse osmosis desalination system is connected to the inlet of a triple-effect multi-stage evaporator via pipe E. A pump on pipe E transports the concentrated high-salt wastewater to the evaporator. The product water outlets of the primary and secondary reverse osmosis units are connected to the inlet of an intermediate water tank via pipes G and H, respectively, transporting the treated freshwater to the intermediate water tank.

[0026] Triple-effect multi-stage evaporator: This type of evaporator consists of three evaporators, each called a first effect, and is a falling film evaporator. It utilizes the thermal energy of steam to evaporate and concentrate high-salt wastewater. The triple-effect multi-stage evaporator employs the principle of multi-effect evaporation, fully utilizing the thermal energy of steam and improving energy efficiency. Furthermore, the first-effect evaporator treats high-concentration wastewater (8-12% TDS) from a multi-stage series reverse osmosis desalination system. It uses a forced circulation evaporator (FC) design, operating at a temperature of 110-120℃, and maintains stable evaporation of high-solids-content materials through an external heating chamber and a circulating pump. The second-effect evaporator receives secondary steam from the first effect as a heat source and uses a falling film evaporator (FF) design, operating at a temperature of 90-100℃, treating intermediate-concentration wastewater (15%-20% TDS) with high evaporation efficiency and low energy consumption. The third-effect evaporator utilizes the secondary steam from the second-effect evaporator, also employing a falling film evaporator design. Operating at 70-80℃, it treats near-saturated high-salt wastewater (22%-25% TDS), with the final concentrate entering the crystallization system. Simultaneously, the triple-effect multi-stage evaporator uses thermal steam recompression, increasing the pressure and temperature of the secondary steam from the third effect before reusing it as a supplementary heat source to the first effect, significantly improving system thermal efficiency and reducing steam consumption by over 30%. The concentrate outlet of the triple-effect multi-stage evaporator is connected to the crystallizer inlet via pipe F, with a pump on pipe F transporting the concentrated high-salt solution to the crystallizer. Simultaneously, the condensate outlet of the triple-effect multi-stage evaporator is connected to the intermediate water tank inlet via pipe I, recovering the condensate generated during evaporation back to the intermediate water tank for water reuse.

[0027] Crystallizer: In the crystallizer, the concentrated high-salt solution is further cooled and crystallized, causing the salt to precipitate from the solution and form crystals. The discharge end of the crystallizer is connected to the feed pipe of the centrifuge via pipe K, conveying the mixture containing crystals to the centrifuge. Furthermore, the crystallizer adopts a DTB-type crystallizer (baffle crystallizer), which promotes the orderly crystallization of salts by precisely controlling the cooling rate and stirring intensity, obtaining a crystal product with uniform particle size.

[0028] Centrifuge: Used to separate crystals from mother liquor. The centrifugal force generated by high-speed rotation rapidly separates the crystals and mother liquor, resulting in high-purity salt crystals and enabling salt recovery. Furthermore, a horizontal screw discharge centrifuge is used to achieve highly efficient separation of crystals and mother liquor, with a separation factor >2000g and crystal moisture content <5%.

[0029] Intermediate water tank: This tank serves to store and regulate water quality. It receives permeate from the primary and secondary reverse osmosis units, as well as condensate from the triple-effect multi-stage evaporator, mixing and storing this freshwater. The outlet of the intermediate water tank is connected to the inlet of the reclaimed water reverse osmosis desalination system via pipe J, providing a water source for reclaimed water treatment.

[0030] Reclaimed water reverse osmosis desalination system: further desalinates the water in the intermediate water tank to meet reuse standards, so that it can be used in some stages of industrial production and realize the recycling of water resources.

[0031] The beneficial effects of this utility model are as follows:

[0032] (1) This utility model can perform hardening, sedimentation and filtration pretreatment on high-salt industrial wastewater to remove suspended solids, colloidal substances, hardness and some organic matter in the wastewater, provide suitable feed water quality for subsequent reverse osmosis membrane concentration, prevent reverse osmosis membrane fouling, and reduce the cleaning frequency and cleaning cost of reverse osmosis membrane.

[0033] (2) This utility model adopts a multi-stage series reverse osmosis desalination system. With the multi-stage series combination design of reverse osmosis (RO) elements, the wastewater is concentrated in stages, which can reduce the evaporation treatment volume by 60%~70% and improve the overall treatment capacity of the system by more than 40%.

[0034] (3) This utility model uses a three-effect multi-stage evaporator to evaporate and concentrate the concentrated water after reverse osmosis membrane treatment. Based on the working principle of multi-stage evaporation of the existing three-effect multi-stage evaporator, the secondary steam generated in the previous effect is used as the heating source of the next effect, thereby realizing the multiple utilization of heat energy and significantly reducing energy consumption.

[0035] (4) This utility model improves the salt recovery rate through the synergistic effect of pretreatment + membrane separation concentration + triple-effect multi-stage evaporation. At the same time, the salt obtained after crystallization treatment has high purity, realizing the resource utilization of salt. Attached Figure Description

[0036] To more clearly illustrate the technical solution of this utility model, the drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the structure of this utility model.

[0038] In the diagram, 1-Equalization tank, 2-Hardness removal tank, 3-Reaction sedimentation tank, 4-Multi-media filter, 5-First-stage reverse osmosis unit, 6-Second-stage reverse osmosis unit, 7-Triple-effect multi-stage evaporator, 8-Crystallizer, 9-Intermediate water tank, 10-Reclaimed water reverse osmosis desalination system. Detailed Implementation

[0039] To make the objectives, features, and advantages of this utility model more apparent and understandable, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this patent, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this patent.

[0040] Example 1

[0041] Combination Figure 1 This utility model provides a high-salt industrial wastewater treatment device, including an equalization tank 1. The outlet of the equalization tank 1 is connected to the inlet of a hardening tank 2 via pipe A. The outlet of the hardening tank 2 is connected to the inlet of a reaction sedimentation tank 3 via pipe B. The outlet of the reaction sedimentation tank 3 is connected to the inlet of a multi-media filter 4 via pipe C. The multi-media filter 4 is connected to the inlet of a multi-stage series reverse osmosis desalination system via pipe D. The concentrated water outlet of the multi-stage series reverse osmosis desalination system is connected to the inlet of a triple-effect multi-stage evaporator 7 via pipe E. The concentrated liquid outlet of the triple-effect multi-stage evaporator 7 is connected to the inlet of a crystallizer 8 via pipe F. Water pumps are installed on pipes A, B, C, D, E, and F.

[0042] The equalization tank 1, hardening tank 2, and reaction sedimentation tank 3 of this utility model are all conventional sewage treatment devices in the prior art, which can be obtained by self-construction or purchase.

[0043] This utility model's multi-media filter 4 is filled with two layers of filter material: a quartz sand layer (2-4 mm) and an activated carbon layer (1-2 mm) from top to bottom. Quartz sand has excellent filtration performance, removing suspended solids and some colloidal substances from wastewater; activated carbon has a large specific surface area, enabling it to adsorb organic matter and odors from wastewater. The multi-media filter further removes impurities from wastewater through physical filtration, improving wastewater quality. The particle size design (quartz sand 2-4 mm, activated carbon 1-2 mm) optimizes water flow distribution, prevents clogging, and improves filtration efficiency.

[0044] This utility model relates to a multi-stage series reverse osmosis desalination system, comprising a primary reverse osmosis unit 5 and a secondary reverse osmosis unit 6 connected in series. Both the primary and secondary reverse osmosis units 5 and 6 utilize fouling-resistant brackish water reverse osmosis membrane elements, operating at a pressure of 4.5~5.5 MPa. The system is equipped with a variable frequency high-pressure pump to increase the concentrate recirculation ratio, increase the raw water flow rate at the membrane surface, and improve the concentration ratio, effectively mitigating membrane scaling. Simultaneously, both units are equipped with an online chemical cleaning device that automatically triggers the cleaning program based on changes in transmembrane pressure differential (TMP), employing an alternating acid-base cleaning process to restore membrane flux and extend membrane life to 3~5 years.

[0045] The crystallizer 8 of this invention adopts a DTB-type crystallizer (guide tube baffle crystallizer), which promotes the orderly crystallization of salts by precisely controlling the cooling rate and stirring intensity, thereby obtaining a crystal product with uniform particle size. This invention also includes a centrifuge, the feed pipe of which is connected to the discharge end of the crystallizer 8 through pipe K.

[0046] The method of using this utility model is as follows:

[0047] (1) Open the inlet valve of high-salt industrial wastewater to enter the equalization tank 1, turn on the water pump to pump the wastewater in the equalization tank 1 into the hardening tank 2, gradually add calcium hydroxide and sodium carbonate to the hardening tank 2, control the pH value at about 8.5, and perform hardening treatment in the hardening tank 2.

[0048] (2) Pump water from the hardening tank 2 into the reaction sedimentation tank 3, gradually add coagulant (PAC 50~100mg / L, PAM 0.5~1mg / L), observe the formation of flocs, and control the turbidity of the effluent from the reaction sedimentation tank 3 to <5 NTU;

[0049] (3) The effluent from the reaction sedimentation tank 3 is pumped into a multi-stage series reverse osmosis desalination system, where it undergoes reverse osmosis treatment in the primary reverse osmosis unit 5 and the secondary reverse osmosis unit 6, respectively, including:

[0050] First stage reverse osmosis unit 5: First, perform low-pressure flushing (0.2~0.3MPa) for 10~15 minutes to remove air from the membrane elements. Gradually adjust the reflux valve and high-pressure reflux pump frequency to control the inlet water pressure to 4.5~5.5MPa. The initial recovery rate is controlled at 40%~50%. After the operation is stable, gradually increase it to 60%~65%. Monitor the conductivity of the product water and keep it stable within the range of <500μS / cm.

[0051] Secondary reverse osmosis unit 6: First, perform low-pressure flushing (0.2~0.3MPa) for 10~15 minutes to remove air from the membrane elements. Gradually adjust the reflux valve and high-pressure reflux pump frequency to control the inlet water pressure to 4.5~5.5MPa, with the initial recovery rate controlled at 40%~50%. After stable operation, gradually increase it to 60%~65%, and monitor the permeate conductivity, stabilizing it within the range of <500μS / cm.

[0052] (4) The concentrated water produced by reverse osmosis enters the triple-effect multi-stage evaporator 7, including: starting the third effect → second effect → first effect evaporator in sequence to ensure that the secondary steam of the previous effect can be stably supplied to the next effect; controlling the heating steam pressure of the first effect at 0.3~0.4MPa and the temperature at 110~120℃; adjusting the flow rate of the circulation pumps of each effect to maintain the liquid level of the evaporator at 50%~70%;

[0053] (5) The density of the concentrated liquid after evaporation reaches 1.25~1.30 g / cm³. 3 Pump the solution into crystallizer 8 and control the cooling rate to 5~10℃ / h and the stirring intensity to 30~50rpm to obtain uniform crystals (industrial waste salt).

[0054] In some specific embodiments, this invention also includes an intermediate water tank 9. The inlet of the intermediate water tank 9 is connected to the product water outlet of the first-stage reverse osmosis unit 5 via pipe G. The inlet of the intermediate water tank 9 is also connected to the product water outlet of the second-stage reverse osmosis unit 6 via pipe H. The condensate outlet of the triple-effect multi-stage evaporator 7 is connected to the inlet of the intermediate water tank 9 via pipe I. This invention also includes a reclaimed water reverse osmosis desalination system 10. The inlet of the reclaimed water reverse osmosis desalination system 10 is connected to the outlet of the intermediate water tank 9 via pipe J. The product water of the reclaimed water reverse osmosis desalination system 10 is used as reclaimed water. The intermediate water tank 9 serves to store and regulate water quality. It receives the product water from the first-stage reverse osmosis unit 5 and the second-stage reverse osmosis unit 6, as well as the condensate from the triple-effect multi-stage evaporator 7, mixing and storing this fresh water. The outlet of the intermediate water tank 9 is connected to the inlet of the reclaimed water reverse osmosis desalination system 10 via pipe J, providing a water source for reclaimed water treatment. The reverse osmosis desalination system 10 further desalinates the water in the intermediate water tank 9 to meet the reuse standards, so that it can be used in some stages of industrial production and realize the recycling of water resources.

[0055] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-salinity industrial wastewater treatment device, comprising an equalization tank, characterized in that, The outlet of the equalization tank is connected to the inlet of the hardening tank via pipe A. The outlet of the hardening tank is connected to the inlet of the reaction sedimentation tank via pipe B. The outlet of the reaction sedimentation tank is connected to the inlet of the multi-media filter via pipe C. The multi-media filter is connected to the inlet of the multi-stage series reverse osmosis desalination system via pipe D. The concentrate outlet of the multi-stage series reverse osmosis desalination system is connected to the inlet of the triple-effect multi-stage evaporator via pipe E. The concentrate outlet of the triple-effect multi-stage evaporator is connected to the inlet of the crystallizer via pipe F. Water pumps are installed on pipes A, B, C, D, E, and F.

2. The high-salinity industrial wastewater treatment device as described in claim 1, characterized in that, The multi-media filter is filled with a layer of quartz sand and a layer of activated carbon from top to bottom.

3. The high-salinity industrial wastewater treatment device as described in claim 2, characterized in that, The quartz sand in the quartz sand layer has a particle size of 2-4 mm, and the activated carbon in the activated carbon layer has a particle size of 1-2 mm.

4. The high-salinity industrial wastewater treatment device as described in claim 1, characterized in that, A multi-stage series reverse osmosis desalination system includes a first-stage reverse osmosis unit and a second-stage reverse osmosis unit connected in series.

5. The high-salinity industrial wastewater treatment device as described in claim 4, characterized in that, It also includes an intermediate water tank, the inlet of which is connected to the product water outlet of the first-stage reverse osmosis unit via pipe G, and the inlet of the intermediate water tank is also connected to the product water outlet of the second-stage reverse osmosis unit via pipe H.

6. The high-salinity industrial wastewater treatment device as described in claim 5, characterized in that, The condensate outlet of the triple-effect multistage evaporator is connected to the inlet of the intermediate water tank via pipe I.

7. The high-salinity industrial wastewater treatment device as described in claim 5, characterized in that, It also includes a reclaimed water reverse osmosis desalination system, the inlet of which is connected to the outlet of the intermediate water tank via pipe J.

8. The high-salinity industrial wastewater treatment device as described in claim 1, characterized in that, It also includes a centrifuge, whose feed pipe is connected to the outlet of the crystallizer via pipe K.

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