Precipitation desalting recycling process for high-salinity wastewater

Abstract

The invention discloses a high-salinity wastewater precipitation desalting recycling process, and relates to the related field of high-salinity wastewater treatment. The wastewater treatment scheme disclosed by the invention has the advantages that the removal efficiency of sulfate radicals and chloride ions is remarkably improved by combining a multi-stage treatment process with the application of a high-efficiency agent and a flocculating agent, and the final effluent quality reaches the recycling standard. According to the scheme, the dosage of chemicals in each treatment stage is optimized, advanced technologies such as membrane separation, electrodialysis and electrochemical treatment are introduced, it is ensured that pollutants in the wastewater are thoroughly removed, generated by-products such as ettringite and Friedel's salt can be reutilized, the resource utilization rate is further increased, meanwhile, the hydraulic retention time is reasonably distributed, and the treatment cost is reduced. The sufficiency of each reaction process is ensured, and the whole scheme is efficient, environment-friendly, economical and feasible.

Description

Technical Field

[0001] The invention relates to the field of high-salt wastewater treatment, and in particular to a high-salt wastewater precipitation desalination and recycling process. Background Art

[0002] High-salt wastewater refers to industrial or domestic wastewater containing a high concentration of dissolved salts, usually mainly inorganic salts such as chlorides, sulfates, and carbonates. Its salt concentration is usually more than 1% (10,000 mg / L). This type of wastewater is widely sourced from the chemical, petroleum, food processing, pharmaceutical and other industries. It is difficult to treat high-salt wastewater because high salt concentrations can affect the biological treatment effect, corrode equipment, and increase treatment costs. Effective treatment technologies include evaporation crystallization, membrane separation, ion exchange and other methods.

[0003] In the actual treatment process of high-salt wastewater, the following problems exist: During the process of adding the agent, a fixed position is used for addition, resulting in a weak dilution effect and affecting the overall treatment efficiency. Summary of the invention

[0004] Therefore, in order to solve the above-mentioned shortcomings, the present invention provides a high-salinity wastewater precipitation desalination and recycling process.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme: a high-salinity wastewater precipitation desalination recycling process, the steps are as follows: S1 Preliminary desulfurization treatment: A preliminary desulfurization tank is used to add magnesium-based adsorbents and chitosan-based flocculants to the pretreated wastewater, and the auxiliary adding device is used to add them so that sulfate reacts with magnesium ions to form magnesium sulfate precipitation to remove sulfate. The magnesium-based adsorbent is added in an amount of 3 times the molar concentration of sulfate in water, and the chitosan-based flocculant is added in an amount of 30 mg / L. The residence time is 1 hour, and the sulfate concentration is reduced from 3027 mg / L to about 900 mg / L, and some chloride ions are removed; S2 deep desalination treatment: using a deep desalination tank, adding calcium aluminum oxide and iron aluminum oxide, and adding through an auxiliary adding device to continue to remove sulfate and chloride ions. During the reaction, stable calcium aluminum-based composite salts and sulfate precipitation are generated. The calcium aluminum composite oxide is added in an amount of 3 times the molar concentration of sulfate and chloride ions in the water, and the iron aluminum oxide is added in an amount of 1 times the molar concentration of sulfate and chloride ions in the water. The residence time is 2 hours, and the sulfate concentration is reduced from 900 mg / L to <10 mg / L, and the chloride concentration is reduced from 3170 mg / L to 1000 mg / L; S3 sedimentation tank treatment: The treated wastewater from the deep desalination tank contains suspended matter and incompletely settled sediments. Chitosan-based modified flocculants are added and added through auxiliary adding devices. The calcium-aluminum-based composite salts, magnesium sulfate, and calcium aluminate precipitates in the water are deposited at the bottom of the tank. The hydraulic retention time is 2 hours, and then the solid-liquid separation is carried out into supernatant and sediment. S4 membrane separation treatment: nanofiltration membrane system is used, and the supernatant enters the nanofiltration membrane system to remove most of the chloride ions and residual sulfate ions. The sulfate ions in the effluent are less than 10 mg / L, and the chloride ions are less than 200 mg / L. S5 Electrodialysis Concentration: The electrodialysis system is used to further concentrate the brine after membrane separation to recover chloride and sulfate, and the ion concentration in the wastewater is further reduced by electrodialysis; S6 electrochemical treatment: The electrochemical oxidation system is used to electrochemically treat the residual organic matter after membrane separation. A strong oxidant is generated under the action of the electric field to decompose the residual organic matter and the refractory chloride ions. S7 reuse treatment: Recycled water that has undergone multi-stage combined treatment (chemical precipitation, membrane separation, electrodialysis, and electrochemical treatment) can be directly used in the desulfurization tower and circulated within the plant.

[0006] Preferably, the auxiliary adding device includes two groups of relatively arranged supports for support, a connecting shaft arranged at the upper inner ends of the two groups of supports, a transmission box arranged at the front end of the rear end support, a first motor arranged at the front end of the transmission box, a positioning mechanism arranged on the outer side of the support, and a spreading mechanism arranged on the inner side of the two groups of positioning mechanisms.

[0007] Preferably, a driving pulley connected to the output shaft of the first motor is provided at the lower end of the transmission box, the outer side of the driving pulley is connected to a driven pulley via a synchronous belt, and the middle part of the driven pulley is connected to the connecting shaft.

[0008] Preferably, the positioning mechanism includes a rotating rod connected to the outside of the connecting shaft, a pushing rod hinged to the other end of the rotating rod, a sliding member hinged to the other end of the pushing rod, a supporting guide member movably embedded in the sliding member, and a guide column arranged in the middle of the sliding member and passing through the supporting guide member on the outside, and the bottom of the supporting guide member is fixed to the support.

[0009] Preferably, a guide groove is provided at the inner upper end of the support guide member, and the sliding member is movably embedded in the guide groove.

[0010] Preferably, a V-shaped strip groove is opened in the middle of the sliding member, a guide column is movably embedded in the strip groove, an inverted C-shaped guide groove is opened in the upper end of the supporting guide member, and the guide column penetrates the strip groove and is movably embedded in the guide groove.

[0011] Preferably, the back side of the guide column is locked with a limiting disk, and the outer diameter of the limiting disk is greater than the width of the guide groove.

[0012] Preferably, the sprinkling mechanism includes a side piece connected to the inner side of the guide column, a pressure plate arranged on the inner side of the side piece, a fixed box arranged on the top of the pressure plate, a second motor installed at the rear end of the top of the fixed box, a rotating tube passing through the middle of the pressure plate and connected to the fixed box, and a toggle plate arranged at the lower end of the outer side of the rotating tube, the lower end of the rotating tube is provided with a spray hole corresponding to the gap position between each group of toggle plates, and the top of the rotating tube is open.

[0013] Preferably, a driving wheel connected to the output shaft of the second motor is provided at the rear end of the fixed box, the outer side of the driving wheel rotates synchronously with the driven wheel through a connecting belt, and the middle part of the driven wheel is connected to the upper end of the rotating tube.

[0014] Preferably, the rotating tube is placed in the fixed box and has discs at the upper and lower ends.

[0015] Beneficial effects of the present invention: The wastewater treatment scheme of the present invention has the advantages that the removal efficiency of sulfate and chloride ions is significantly improved through the use of a multi-stage treatment process combined with high-efficiency chemicals and flocculants, and the final effluent water quality reaches the reuse standard. The scheme optimizes the dosage of chemicals in each treatment stage, and introduces advanced technologies such as membrane separation, electrodialysis and electrochemical treatment to ensure the complete removal of pollutants in the wastewater. The generated by-products such as calcium sulfonate and Friedel salt can be reused, further improving resource utilization. At the same time, the hydraulic retention time is reasonably allocated to ensure the adequacy of each reaction process. The overall scheme is efficient, environmentally friendly and economically feasible.

[0016] The present invention is achieved by adopting an auxiliary adding device when adding the medicine. The auxiliary adding device is equipped with a positioning mechanism and a spreading mechanism. The spreading mechanism can add the medicine into the wastewater, and cooperate with a motor-driven pulley group to perform simultaneous dilution while adding, so as to perform uniform and stable dilution. The spreading mechanism is position-adjusted by the positioning mechanism, and can realize left and right reciprocating movement, and move up and down during the left and right movement, and cooperate with a pressure plate to efficiently dilute the medicine in the wastewater, so as to improve the efficiency of addition and dilution. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the auxiliary adding device of the present invention; Figure 2 It is a schematic diagram of the transmission box structure of the present invention; Figure 3 It is a schematic diagram of the structure of the positioning mechanism of the present invention; Figure 4 It is a schematic diagram of the guide groove structure of the present invention; Figure 5 It is a schematic diagram of the structure of the sprinkling mechanism of the present invention; Figure 6It is a structural schematic diagram of the fixed box of the present invention.

[0018] Among them: support-1, connecting shaft-2, transmission box-3, first motor-4, adjustment mechanism-5, spreading mechanism-6, driving pulley-3a, synchronous belt-3b, driven pulley-3c, rotating rod-51, pushing rod-52, sliding member-53, supporting guide member-54, guide column-55, guide groove-54a, side member-61, pressure plate-62, fixed box-63, second motor-64, rotating tube-65, toggle plate-66, driving wheel-63a, connecting belt-63b, driven wheel-63c. DETAILED DESCRIPTION

[0019] In order to further explain the technical solution of the present invention, it is described in detail below through specific embodiments.

[0020] The invention provides a high-salt wastewater precipitation desalination recycling process, S1 preliminary desulfurization treatment: adopting a preliminary desulfurization tank, adding a magnesium-based adsorbent and a chitosan-based flocculant to the pretreated wastewater, and adding them through an auxiliary adding device, so that sulfate radicals react with magnesium ions to generate magnesium sulfate precipitates, and sulfate radicals are removed. The magnesium-based adsorbent has an addition amount of 3 times the molar concentration of sulfate radicals in water, and the chitosan-based flocculant has an addition amount of 30 mg / L. The residence time is 1 hour, and the sulfate radical concentration is reduced from 3027 mg / L to about 900 mg / L, and part of the chloride ions are removed; S2 deep desalination treatment: adopting a deep desalination tank, adding calcium aluminum oxide and iron aluminum oxide, and adding them through an auxiliary adding device, and continuing to remove sulfate radicals and chloride ions. During the reaction, stable calcium aluminum-based composite salts and sulfate precipitates are generated. The calcium aluminum composite oxide has an addition amount of 3 times the molar concentration of sulfate radicals and chloride ions in water, and the iron aluminum oxide has an addition amount of 1 times the molar concentration of sulfate radicals and chloride ions in water. The residence time is 2 hours, and the sulfate radical concentration is reduced from 900 mg / L is reduced to <10 mg / L, and the chloride ion concentration is reduced from 3170 mg / L to 1000 mg / L; S3 sedimentation tank treatment: the treated wastewater from the deep desalination tank contains suspended matter and incompletely settled sediments, chitosan-based modified flocculants are added, and the calcium-aluminum-based composite salts, magnesium sulfate, and calcium aluminate precipitates in the water are deposited at the bottom of the pool. The hydraulic retention time is 2 hours, and then the solid-liquid separation is into supernatant and sediment; S4 membrane separation treatment: a nanofiltration membrane system is used, and the supernatant enters the nanofiltration membrane system to remove most of the chloride ions and residual sulfate, and the effluent sulfate is <10 mg / L, and the chloride ion is <200 mg / L; S5 electrodialysis concentration: the electrodialysis system is used to further concentrate the brine after membrane separation to recover chloride and sulfate, and the ion concentration in the wastewater is further reduced by electrodialysis; S6 electrochemical treatment: the electrochemical oxidation system is used to electrochemically treat the residual organic matter after membrane separation, and a strong oxidant is generated under the action of the electric field to decompose the residual organic matter and the difficult-to-degrade chloride ions; S7 reuse treatment: the reused water after multi-stage combined treatment (chemical precipitation, membrane separation, electrodialysis, electrochemical treatment) can be directly used in the desulfurization tower and in-plant circulation; S8 solid treatment and resource utilization: a dehydrator is used to dehydrate the solid precipitate (ettringite, Friedel salt, etc.) in the sedimentation tank. The dehydrated solid can be utilized as a resource. Solid treatment: the dehydrated solid is mainly composed of ettringite and Friedel salt, which can be further processed into adsorbents or ion exchangers for water treatment or other industrial applications.

[0021] The changes in wastewater treatment process parameters are shown in the following table:

[0022] See also Figure 1-Figure 2The auxiliary adding device includes a support 1 for supporting, and the support 1 is provided with two groups. The two groups of supports 1 are arranged opposite to each other. The upper ends of the inner sides of the supports 1 are connected by a connecting shaft 2. A transmission box 3 is provided at the upper end of the front end surface of the rear end support 1, and a first motor 4 is provided at the lower end of the front end surface of the transmission box 3. A positioning mechanism 5 is provided on the outer side of the support 1. A spreading mechanism 6 is provided at the right end of the inner side of the two groups of positioning mechanisms 5. The spreading mechanism 6 adjusts the position along with the positioning mechanism 5. The spreading mechanism 6 delivers the agent into the wastewater and spreads it to improve the dilution efficiency; A driving pulley 3a connected to the output shaft of the first motor 4 is provided at the lower end of the transmission box 3. The outer side of the driving pulley 3a is connected to the driven pulley 3c through a synchronous belt 3b. The middle part of the driven pulley 3c is connected to the connecting shaft 2, and the connecting shaft 2 rotates following the driven pulley 3c.

[0023] See also Figure 3-Figure 4 The positioning mechanism 5 includes a rotating rod 51 arranged on the outside of the support 1 and connected to the connecting shaft 2, the other end of the rotating rod 51 is hinged to the pushing rod 52, the other end of the pushing rod 52 is hinged to the sliding member 53, the outer side of the sliding member 53 is connected to the supporting guide member 54, the bottom of the supporting guide member 54 is fixed to the right end of the support 1, a guide groove is provided at the inner upper end of the supporting guide member 54, and the sliding member 53 is movably embedded in the guide groove, a V-shaped strip groove is provided in the middle of the sliding member 53, and a guide column 55 is movably embedded in the strip groove, an inverted C-shaped guide groove 54a is provided at the inner upper end of the supporting guide member 54, the guide column 55 penetrates the strip groove and then movably embeds into the guide groove 54a, and the back of the guide column 55 is locked with a limiting disk, and the outer diameter of the limiting disk is greater than the width of the guide groove 54a.

[0024] See also Figure 5-Figure 6 The sprinkling mechanism 6 includes a side piece 61 connected to the inner side of the guide column 55, and the inner sides of the two groups of side pieces 61 are connected to a pressing plate 62. The two ends of the pressing plate 62 are in an arc shape. A fixed box 63 is provided at the top rear end of the pressing plate 62. A second motor 64 is provided at the top rear end of the fixed box 63. A rotating tube 65 is provided at the front end of the fixed box 63. The bottom of the rotating tube 65 passes through the pressing plate 62. A flexible toggle plate 66 is fixed to the lower end of the outer side of the rotating tube 65. The outer edge of the toggle plate 66 is in a pointed shape. A spray hole is provided at the lower end of the rotating tube 65 corresponding to the gap between each group of toggle plates 66. The top of the rotating tube 65 is open and can be connected to an external quantitative pump. A driving wheel 63a connected to the output shaft of the second motor 64 is provided at the rear end of the fixed box 63. The outer side of the driving wheel 63a rotates synchronously with the driven wheel 63c through a connecting belt 63b. The middle part of the driven wheel 63c is connected to the upper end of the rotating tube 65, and the rotating tube 65 is placed in the fixed box 63 and has discs fixed at the upper and lower ends. The discs are used for limiting, which is convenient for lifting and lowering, but does not affect the rotation.

[0025] The specific implementation process of the auxiliary adding device is as follows: First, install the auxiliary adding device to the top of the equipment where the reagent and flocculant need to be added, and then connect the external metering pump to the top of the rotating tube 65 for feeding; Then, the feeding starts, and the medicine enters the rotating tube 65 and can be discharged from the spray hole. Then, the second motor 64 is started to work, and the second motor 64 drives the driving wheel 63a to rotate. The outer side of the driving wheel 63a drives the driven wheel 63c to rotate through the connecting belt 63b. During the rotation of the driven wheel 63c, the rotating tube 65 and the outer toggle plate 66 can be driven to rotate and spread in the wastewater, so as to facilitate the rapid dilution of the medicine. When the equipment is used to efficiently dilute and mix the reagents in the wastewater in the left and right range, the first motor 4 is started to work, and the first motor 4 drives the active pulley 3a to rotate, and drives the driven pulley 3c to rotate through the synchronous belt 3b. During the rotation of the driven pulley 3c, the middle connecting shaft 2 follows the rotation, and drives the rotating rods 51 at both ends to rotate, and the rotating rods 51 can act on the pushing rod 52, and the pushing rod 52 can drive the sliding member 53 to move left and right in the supporting guide member 54. During the movement, the guide column 55 in the middle of the sliding member 53 drives the side member 61 to make the pressure plate 62 follow the movement, and cooperate with the guidance of the guide groove 54a and the strip groove to make the side member 61 move up and down during the left and right reciprocating motion. The pressure plate 62 presses down and lifts the wastewater, and can also toggle the wastewater, cooperate with the toggle plate 66 and the left and right position movement, so as to realize the efficient dilution of the reagent.

[0026] The above description is only a preferred example of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-salinity wastewater precipitation desalination and recycling process, characterized by: Here are the steps: S1 Preliminary desulfurization treatment: A preliminary desulfurization tank is used to add magnesium-based adsorbents and chitosan-based flocculants to the pretreated wastewater, and the auxiliary adding device is used to add them so that sulfate reacts with magnesium ions to form magnesium sulfate precipitation to remove sulfate. The magnesium-based adsorbent is added in an amount of 3 times the molar concentration of sulfate in water, and the chitosan-based flocculant is added in an amount of 30 mg / L. The residence time is 1 hour, and the sulfate concentration is reduced from 3027 mg / L to about 900 mg / L, and some chloride ions are removed; S2 deep desalination treatment: using a deep desalination tank, adding calcium aluminum oxide and iron aluminum oxide, and adding through an auxiliary adding device to continue to remove sulfate and chloride ions. During the reaction, stable calcium aluminum-based composite salts and sulfate precipitation are generated. The calcium aluminum composite oxide is added in an amount of 3 times the molar concentration of sulfate and chloride ions in the water, and the iron aluminum oxide is added in an amount of 1 times the molar concentration of sulfate and chloride ions in the water. The residence time is 2 hours, and the sulfate concentration is reduced from 900 mg / L to <10 mg / L, and the chloride concentration is reduced from 3170 mg / L to 1000 mg / L; S3 sedimentation tank treatment: The treated wastewater from the deep desalination tank contains suspended matter and incompletely settled sediments. Chitosan-based modified flocculants are added and added through auxiliary adding devices. The calcium-aluminum-based composite salts, magnesium sulfate, and calcium aluminate precipitates in the water are deposited at the bottom of the tank. The hydraulic retention time is 2 hours, and then the solid-liquid separation is carried out into supernatant and sediment. S4 membrane separation treatment: nanofiltration membrane system is used, and the supernatant enters the nanofiltration membrane system to remove most of the chloride ions and residual sulfate ions. The sulfate ions in the effluent are less than 10 mg / L, and the chloride ions are less than 200 mg / L. S5 Electrodialysis Concentration: The electrodialysis system is used to further concentrate the brine after membrane separation to recover chloride and sulfate, and the ion concentration in the wastewater is further reduced by electrodialysis; S6 electrochemical treatment: The electrochemical oxidation system is used to electrochemically treat the residual organic matter after membrane separation. A strong oxidant is generated under the action of the electric field to decompose the residual organic matter and the refractory chloride ions. S7 reuse treatment: Recycled water that has undergone multi-stage combined treatment (chemical precipitation, membrane separation, electrodialysis, and electrochemical treatment) can be directly used in the desulfurization tower and circulated within the plant.

2. According to claim 1, a high-salinity wastewater precipitation desalination recycling process is characterized by: The auxiliary adding device includes two groups of supports arranged opposite to each other for support, a connecting shaft arranged at the upper ends of the inner sides of the two groups of supports, a transmission box arranged at the front end of the rear end support, a first motor arranged at the front end of the transmission box, a positioning mechanism arranged at the outer side of the support, and a spreading mechanism arranged inside the two groups of positioning mechanisms.

3. According to claim 2, a high-salinity wastewater precipitation desalination and recycling process is characterized in that: A driving pulley connected to the output shaft of the first motor is arranged at the lower end of the transmission box, the outer side of the driving pulley is connected to the driven pulley through a synchronous belt, and the middle part of the driven pulley is connected to the connecting shaft.

4. According to claim 3, a high-salinity wastewater precipitation desalination and recycling process is characterized by: The positioning mechanism includes a rotating rod connected to the outside of the connecting shaft, a pushing rod hinged to the other end of the rotating rod, a sliding member hinged to the other end of the pushing rod, a supporting guide member movably embedded in the sliding member, and a guide column arranged in the middle of the sliding member and passing through the supporting guide member on the outside, and the bottom of the supporting guide member is fixed to the support.

5. According to claim 4, a high-salinity wastewater precipitation desalination and recycling process is characterized by: A guide groove is provided at the inner upper end of the support guide member, and the sliding member is movably embedded in the guide groove.

6. A high-salinity wastewater precipitation desalination and recycling process according to claim 5, characterized in that: A V-shaped strip groove is provided in the middle of the sliding part, a guide column is movably embedded in the strip groove, an inverted C-shaped guide groove is provided at the upper end of the supporting guide part, and the guide column penetrates the strip groove and then movably embedded in the guide groove.

7. A high-salinity wastewater precipitation desalination and recycling process according to claim 6, characterized in that: The back side of the guide column is locked with a limiting disk, and the outer diameter of the limiting disk is greater than the width of the guide groove.

8. A high-salinity wastewater precipitation desalination and recycling process according to claim 4, characterized in that: The sprinkling mechanism includes a side piece connected to the inner side of the guide column, a pressure plate arranged on the inner side of the side piece, a fixed box arranged on the top of the pressure plate, a second motor installed at the rear end of the top of the fixed box, a rotating tube passing through the middle of the pressure plate and connected to the fixed box, and a toggle plate arranged at the lower end of the outer side of the rotating tube, a spray hole is opened at the lower end of the rotating tube corresponding to the gap position between each group of toggle plates, and the top of the rotating tube is open.

9. A high-salinity wastewater precipitation desalination and recycling process according to claim 8, characterized in that: A driving wheel connected to the output shaft of the second motor is arranged at the rear end of the fixed box, and the outer side of the driving wheel rotates synchronously with the driven wheel through a connecting belt, and the middle part of the driven wheel is connected to the upper end of the rotating tube.

10. A high-salinity wastewater precipitation desalination and recycling process according to claim 9, characterized in that: The rotating tube is placed in the fixed box and is provided with discs at the upper and lower ends.

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