A system for extracting hydrobromic acid from bromine-containing wastewater and a treatment method thereof

Abstract

The application discloses a system for extracting hydrobromic acid from bromine-containing wastewater and a treatment method thereof, and belongs to the field of industrial wastewater treatment. The system comprises a pretreatment system, a bromide ion extraction device, a transformation agent extraction system and a hydrobromic acid extraction system. The bromide ion extraction device adopts ion exchange resin and can selectively extract bromine in water. The transformation agent extraction system comprises an organic matter removal device, a divalent cation removal device and a concentration device. The hydrobromic acid extraction system comprises a bromine separation device and a distillation device. The system extracts an anion salt with a large content and competitive with bromide ions in water as a transformation agent B, transforms the resin, selectively adsorbs the bromide ions in water by the resin, enriches the bromide ions in water, desorbs the saturated bromide ions in the adsorption to a desorption liquid by regeneration A, and then separates and purifies the regeneration agent A and the bromide ions, or acidifies and purifies to obtain a pure hydrobromic acid solution.

Description

Technical Field

[0001] This invention relates to a wastewater treatment system and method, specifically to a system and method for extracting hydrobromic acid from bromine-containing wastewater, belonging to the field of industrial wastewater treatment, and applicable to the treatment of industrial bromine-containing wastewater and the extraction of bromine from seawater and brine. Background Technology

[0002] Hydrobromic acid, as an important chemical raw material, is widely used in fine chemicals, petrochemicals, pharmaceuticals, agriculture, and other fields. However, these companies that use hydrobromic acid as a production raw material all face the problem of excessive bromide ion concentration affecting wastewater discharge. At the same time, the price of hydrobromic acid has been rising continuously, leading to increasingly higher production costs.

[0003] In recent years, my country has placed increasing emphasis on environmental protection and imposed stringent requirements on wastewater discharge standards, leading many enterprises to face significant challenges in wastewater treatment. The presence of bromide ions in water can affect the effectiveness of biological treatment, and the presence of bromide ions in wastewater can also affect COD detection, resulting in higher than normal COD values ​​in the effluent. Bromine is an important chemical raw material; extracting it from water could not only reduce production costs but also alleviate the pressure on wastewater treatment.

[0004] For example, in the PTA (purified terephthalic acid) production industry, p-xylene is generally used as a raw material, and cobalt and manganese are used as catalysts. Air oxidation is carried out in an acetic acid medium to produce crude terephthalic acid (CTA). The crude terephthalic acid is then hydrogenated to remove impurities, followed by crystallization, separation, and drying to obtain the purified terephthalic acid product, i.e., the finished PTA. Because hydrobromic acid is also added during the production process, the resulting bromine-containing wastewater is mainly divided into: gas-phase bromine-containing wastewater—wastewater generated from the absorption of tail gas by alkaline solution; and liquid-phase bromine-containing wastewater—waste liquid containing a large amount of organic matter and residues after the reaction.

[0005] The gas phase wastewater mainly consists of sodium formate, sodium acetate, sodium bromide, sodium carbonate, and sodium bicarbonate, and contains a small amount of oxidant. The liquid phase wastewater mainly consists of sodium acetate, aromatic organic compounds, sodium bromide, and sodium bicarbonate.

[0006] How to remove bromide ions from water has always been a difficult problem to be solved.

[0007] If bromide ions in water are extracted and made into hydrobromic acid for reuse in production, not only can production costs be greatly reduced, but the quality of wastewater can also be improved. Summary of the Invention

[0008] To address the problems existing in the prior art, the present invention provides a system and method for extracting hydrobromic acid from bromine-containing wastewater.

[0009] The present invention adopts the following technical solution:

[0010] This invention is applicable to the treatment of bromine-containing wastewater with a limited number of anions other than bromide (only one or two competing anions exist, or the content of excess competing anions is less than 100 mg / L). When the wastewater system is complex and contains a large number of anions, it is necessary to pre-remove some anions based on the selectivity of the resin, retaining one or two anions, and selecting the retained anions as exchange groups. If other substances affecting the treatment are present in the water, they also need to be removed through pretreatment.

[0011] The core of this invention lies in using a resin with a high content of competitive anions (excluding bromide ions) in water as exchange groups, enabling the resin to selectively adsorb bromide ions from the water. Simultaneously, the same anionic salt acting as the exchange group in the water is extracted and used as a transforming agent B to transform the resin, allowing it to selectively adsorb bromide ions while saving on regenerant costs.

[0012] Furthermore, by selecting regenerant A, which is easily separated from bromide ions, to remove the bromide ions adsorbed on the desorption resin, and then separating regenerant A from the bromide ions in the desorption solution, bromide ions are ultimately extracted from the wastewater. The extracted bromide ions can be used to produce bromine, sodium bromide, or hydrobromic acid. In this invention, the preferred method is to produce hydrobromic acid.

[0013] This invention provides a system for extracting hydrobromic acid from bromine-containing wastewater, wherein the bromine-containing wastewater is sequentially connected to a pretreatment system, a bromide ion extraction device, and a hydrobromic acid extraction device.

[0014] The pretreatment system includes a filter;

[0015] The bromide ion extraction device includes anion exchange resin; the anion exchange resin exchange groups are anions that are abundant in wastewater and compete with bromide ions, and are used to selectively adsorb bromide ions in the water.

[0016] The hydrobromic acid extraction system includes a bromine separation device and a purification device.

[0017] Furthermore, the bromide ion extraction device is also connected to a transformation agent extraction system; the transformation agent extraction system includes an organic matter removal device, a divalent cation removal device, and a concentration device.

[0018] Furthermore, the filter is used to remove suspended solids from the water to protect the stable operation of subsequent systems. The filter includes, but is not limited to, sand filters, precision filters, bag filters, ultrafiltration, or microfiltration devices or systems that can achieve the same filtration purpose.

[0019] Furthermore, if the water contains other substances that may have an impact, such as a large variety of anions or high concentrations of organic matter, these need to be removed in advance. The filter is equipped with a nanofiltration device, an AO reaction tank, and a chemical dosing device; specifically, this includes separating larger organic molecules and divalent or higher ions through nanofiltration, removing organic matter from the water through biochemical treatment, removing anions such as phosphates and sulfates from the water through the addition of chemical agents, or other related technical means before the water enters the filter for further treatment.

[0020] Furthermore, the anion exchange resin includes strong base type, weak base type, macroporous type or gel type resin.

[0021] Furthermore, the selected resins include strong base anion exchange resins such as 201, macroporous strong base anion exchange resins such as D201, and weak base resins such as D301.

[0022] Furthermore, the regenerator extraction system extracts an anionic salt (such as sodium bicarbonate) from water that has a high content and competes with bromide ions for use as a regenerator. When sodium bicarbonate is the main component of the water, the regenerator extracted by the regenerator extraction system is sodium bicarbonate.

[0023] Furthermore, in the aforementioned transformation agent extraction system, the extracted regenerant can be in liquid form, with a concentration required for regeneration of the bromide ion extraction device. Alternatively, a solid transformation agent B can be extracted. When the extracted transformation agent B is solid, a crystallization device and a solid-liquid separation device are sequentially connected after the concentration device. The crystallization device includes, but is not limited to, an evaporative crystallization device or a freeze crystallization device. The solid-liquid separation device includes, but is not limited to, a centrifuge or a filter press.

[0024] Furthermore, the organic matter removal device in the transformation agent extraction system includes, but is not limited to, nanofiltration, microfiltration, electro-oxidation, biochemical devices, activated carbon, and other devices or systems capable of removing organic matter from water. Nanofiltration is preferred. Removing organic matter ensures that the desorption solution is free of organic matter, guarantees the purity of the extracted hydrobromic acid, and allows for classified discharge based on the presence of organic matter in the wastewater.

[0025] Furthermore, the organic matter removal device includes, but is not limited to, nanofiltration, microfiltration, electro-oxidation, biochemical, or activated carbon devices. The organic matter removal device is used to remove organic matter mixed in the transforming agent B, and it can be placed before or after the concentration device. After the concentration device produces transforming agent B, it passes through the organic matter removal device to remove organic matter from the water before reuse, or it passes through a crystallization device or centrifuge to extract solid transforming agent B before reuse.

[0026] Furthermore, the divalent cation removal device includes, but is not limited to, nanofiltration devices or cation exchange resins, which are devices or systems capable of removing divalent and higher ions from water. Nanofiltration devices or ion exchange resins are preferred. If a nanofiltration device is used to separate organic matter in the organic matter removal device, the divalent cation removal device can remove it. The preceding nanofiltration device can simultaneously remove organic matter and divalent and higher ions from the water. If the organic matter removal device is placed after the concentrated water in the concentration device, ion exchange is preferably used to remove divalent and higher cations.

[0027] Furthermore, the concentration device includes, but is not limited to, devices or systems that can concentrate water, such as electrodialysis devices, reverse osmosis devices, or evaporation devices, with electrodialysis devices being the preferred choice.

[0028] Furthermore, the hydrobromic acid extraction system is used to treat the desorption liquid A discharged during the desorption process of the bromide ion extraction device.

[0029] Furthermore, the bromine separation device functions to separate regenerator A and bromide ions in desorption solution A. The bromine separation device includes a combination of a concentration device and a distillation device, a membrane separation device, a combination of a neutralization device and a separation device, or other devices or systems capable of separating regenerator A and bromide ions. The separation device includes a nanofiltration device or an ion exchange resin.

[0030] Furthermore, the purification apparatus includes a distillation apparatus or a combination of a distillation apparatus and a purification apparatus, or a combination of an evaporation apparatus and a purification apparatus, or other apparatus or systems capable of purifying hydrobromic acid.

[0031] Furthermore, the purification device is used to improve product purity and can remove small amounts of bromine contained in hydrobromic acid. If the product purity requirement is low, the purification device may not be required.

[0032] Furthermore, the bromine separation device preferably employs a combination of a concentration unit and a distillation unit. After the desorbed liquid A is concentrated in the concentration unit, it enters the distillation unit, where hydrobromic acid is distilled out from the water based on the differences in the boiling points of the components in the solution. The distilled water produced can be used for regenerator preparation or discharged directly. The concentrated sulfuric acid at the bottom of the distillation can be reused as regenerator A. The concentration unit includes, but is not limited to, evaporators, membrane distillation devices, electrostatic adsorption, and other equipment or systems that can achieve the purpose of concentrating the desorbed liquid A, with the aim of reducing the distillation volume. If a concentration unit is not used, direct distillation is also feasible.

[0033] Furthermore, the bromine separation device can also employ a membrane separation device, which can be a pressure-driven membrane such as an acid-resistant nanofiltration membrane or a reverse osmosis membrane. For example, an acid-resistant membrane can be used to separate sulfuric acid and hydrobromic acid. The separated hydrobromic acid can then be purified by distillation to obtain industrial-grade concentrated hydrobromic acid that meets usage requirements. The separated sulfuric acid can be reused within the system as regenerator A.

[0034] Furthermore, the bromine separation device can also employ a combination of a neutralization device and a separation device. The separation device separates sulfate and bromide ions from the water. When a nanofiltration device is used for bromine separation, the regenerated solution A must first pass through a neutralization device to adjust the pH to the allowable range (pH>4) of the nanofiltration device. The alkali used for neutralization is preferably a transforming agent B extracted from a transforming agent extraction system (when transforming agent B is an alkaline compound). The separated bromide ions will exist in the form of sodium bromide. The sodium bromide solution needs to be acidified to convert sodium ions into hydrogen ions to obtain a hydrobromic acid solution, which can then be distilled to obtain an industrial-grade concentrated hydrobromic acid solution. Alternatively, the sodium bromide solution can be directly concentrated without acidification to obtain a high-concentration sodium bromide solution, or further evaporated and crystallized to obtain solid sodium bromide.

[0035] Furthermore, when the bromine separation device is a combination of a neutralization device and a separation device, the separation device is connected to a concentration device and / or an acidification device, and then connected to a purification device; the concentration device includes equipment or systems such as an electrodialysis device, a reverse osmosis device, an evaporator, a membrane distillation device, and an electrostatic adsorption device that can achieve the purpose of concentrating sodium bromide solution, with the aim of reducing the throughput.

[0036] Furthermore, the acidification device includes, but is not limited to, devices or systems that can convert sodium bromide into hydrobromic acid, such as hydrogen-form cation exchange resins or bipolar membranes. Hydrogen-form ion exchange resins are preferred.

[0037] Furthermore, the bromine separation device includes an oxidation device, an absorption device, and a distillation device connected in sequence. The oxidation device oxidizes bromide ions to bromine by adding an oxidant, and then separates the bromine by stripping or distillation. The absorption device absorbs the bromine by adding a reducing agent, and after purification by a purification device, bromine or hydrobromic acid is obtained. The acid solution obtained after separating the bromide ions is then used as regenerator A. The oxidant includes oxidizing substances such as chlorine, hydrogen peroxide, hypochlorous acid, sodium hypochlorite, concentrated sulfuric acid, chlorine dioxide, sodium hypochlorite, and ozone. The reducing agent includes reducing substances such as sulfur dioxide, formic acid, sodium formate, sodium thiosulfate, sulfurous acid, and sodium sulfite.

[0038] Furthermore, the obtained bromine can be used to produce hydrobromic acid and other related products.

[0039] Furthermore, the purification device includes, but is not limited to, devices or systems capable of adsorbing bromine, such as ion exchange resins, activated carbon, and extraction devices.

[0040] Furthermore, the neutralizing agent selected by the neutralization device includes sodium hydroxide, sodium carbonate, or sodium bicarbonate.

[0041] Furthermore, since formic acid reacts with bromine to produce hydrobromic acid and carbon dioxide when formic acid is used as a reducing agent, and the carbon dioxide is released into the air, the reaction is irreversible, and the only product in water is hydrobromic acid. Therefore, when formic acid or a reducing agent with a similar reaction to bromine is used, an aqueous solution of hydrobromic acid can be directly prepared without subsequent purification equipment.

[0042] This invention also provides a method for extracting hydrobromic acid from bromine-containing wastewater, comprising the following steps:

[0043] 1) Bromine-containing wastewater undergoes a pretreatment system to remove suspended solids;

[0044] 2) The bromide ion extraction device enters the anion exchange resin, where bromide ions in the water are selectively adsorbed onto the resin. The debrominated water from the bromide ion extraction device enters the transformation agent extraction system. In the transformation agent extraction system, after organic matter removal, divalent cation removal, and concentration, or after organic matter removal, divalent cation removal, concentration, crystallization, and solid-liquid separation, transformation agent B is obtained.

[0045] 3) When the bromide ion extraction device is saturated with adsorption, regenerator A is added to the bromide ion extraction device to desorb bromide ions, forming a desorption solution containing regenerator A and hydrobromic acid. The desorption solution is separated from the regenerator A and hydrobromic acid by a bromine separation device. The separated hydrobromic acid is then purified by a purification device. Regenerator A is recycled.

[0046] Alternatively, the desorption solution containing regenerator A and bromide ions described in step 3 can be oxidized and purified to obtain bromine or hydrobromic acid; the oxidation method includes oxidation with an oxidant or oxidation with an oxidant followed by bromine stripping and absorption with a reducing agent.

[0047] 4) After desorption in step 3), the transforming agent B obtained in step 2) is added to the bromide ion extraction device to convert the anion exchange resin exchange groups into anion exchange groups in the waste liquid to be treated that compete with bromide ions, and then used for the recycling treatment of bromine-containing wastewater.

[0048] Furthermore, the transforming agent B is preferably a salt with a high content in water and that competes with bromide ions. When the wastewater is gaseous bromine-containing wastewater generated during PTA production (oxidation tail gas alkaline solution absorption wastewater), and the alkalinity in the water mainly exists in the form of sodium bicarbonate, then the transforming agent B is sodium bicarbonate. The transforming agent B includes sodium carbonate, sodium bicarbonate, sodium hydroxide, sodium chloride, or sodium sulfate.

[0049] Furthermore, the regenerator A includes compounds such as sulfuric acid, hydrochloric acid, nitric acid, sodium benzoate, sodium phenolate, or sodium citrate, which can desorb bromide ions from the resin and can be separated from bromide ions (such as organic matter, inorganic matter, acid, and alkali).

[0050] Furthermore, the regenerator A is preferably sulfuric acid or hydrochloric acid.

[0051] Furthermore, when sulfuric acid is selected as the regenerator A, the desorption solution mainly consists of sulfuric acid and hydrobromic acid coexisting.

[0052] Furthermore, the desorption solution A enters the bromine separation unit to separate sulfuric acid and hydrobromic acid. The resulting hydrobromic acid solution enters the distillation unit and is distilled to obtain a hydrobromic acid solution.

[0053] Furthermore, when formic acid or a reducing agent in a similar form to the reaction of formic acid with bromine is used, an aqueous solution of hydrobromic acid is directly prepared, eliminating the need for purification equipment.

[0054] Furthermore, during the regeneration of the anion exchange resin, regenerant A is first used to desorb bromide ions, and then conversion agent B is used to convert it to a working state. When the resin is saturated with bromide ions, regenerant A is first used to displace the bromide ions from the resin. The resulting desorption solution A enters the hydrobromic acid extraction system, and then conversion agent B is used to convert the resin exchange groups into competing anion groups in the waste liquid to be treated, ensuring that the resin primarily adsorbs bromide ions during operation and improving its working exchange capacity. Regenerant A is preferably sulfuric acid, but hydrochloric acid, nitric acid, sodium benzoate, sodium citrate, etc., which can displace bromide ions from the resin and subsequently separate organic matter, inorganic matter, acids, and alkalis. Conversion agent B is preferably a salt with a high content in the water that competes with bromide ions. When the water is mainly composed of sodium bicarbonate, sodium bicarbonate is used as conversion agent B.

[0055] Furthermore, during the regeneration of the anion exchange resin, regenerator A and conversion agent B are selected. When the resin is saturated with adsorbed bromide ions, regenerator A is first used to desorb the bromide ions from the resin. The resulting desorbed liquid A enters the hydrobromic acid extraction system. Then, conversion agent B is used to convert the resin exchange groups into competing anion groups in the waste liquid to be treated, ensuring that the resin mainly adsorbs bromide ions during operation and improving the working exchange capacity.

[0056] Furthermore, a method for extracting hydrobromic acid from bromine-containing wastewater, under any of the following circumstances:

[0057] a. When using only regenerator A to regenerate the resin, the bromide ion utilization rate on the resin in the working state is greater than 40%, that is, until the resin is saturated. The exchange capacity used to adsorb bromide ions on the resin accounts for more than 40% of the resin's total exchange capacity. When the resin adsorbs bromide ions in water, there is a balance between the ratio of competing ions and bromide ions in the water. When using only regenerator A and directly operating the system with a bromide ion utilization rate greater than 40%, the effect is the same as that produced after transformation with converter B. Therefore, converter B and the supporting equipment for generating converter B are not required.

[0058] b. When using a multi-stage ion exchange system to treat bromine-containing wastewater, since the first-stage effluent has already removed most of the bromide ions, the ions entering the second stage are mainly competitive ions. At this point, the second-stage influent is equivalent to a low-concentration conversion agent B. When the first stage is saturated, the second stage is essentially complete, and its bromide ion exchange capacity is far from its maximum. In this case, the second stage can be reused as the first stage, with the ion exchanger regenerated using regenerant A as the second stage. This process can be repeated, with each regeneration using only regenerant A to regenerate the first-stage resin.

[0059] c. If the concentration of anions generated by regenerant A in the system wastewater exceeds the discharge requirements when the system meets the above two conditions, conversion agent B must be used. Conversion liquid B will transfer the anions generated by regenerant A on the resin to the conversion waste liquid, which can be discharged separately or treated in other ways.

[0060] The processing method includes the following steps:

[0061] 1) Bromine-containing wastewater undergoes a pretreatment system to remove suspended solids;

[0062] 2) When the bromide ion extraction device is saturated with adsorption, regenerator A is added to the bromide ion extraction device to desorb the bromide ions, forming a desorption solution containing regenerator A and bromide ions. The desorption solution is then separated from the bromide ions by a bromide separation device. The separated bromide ions are then purified by a purification device. Regenerator A is recycled.

[0063] The regenerator A is a compound capable of desorbing bromide ions from the resin and separating them from the bromide ions, including sulfuric acid, hydrochloric acid, nitric acid, sodium benzoate, sodium phenolate, or sodium citrate; the desorption solution containing regenerator A and bromide ions in step 2) is oxidized and purified to obtain bromine or hydrobromic acid; the oxidation method includes oxidation with an oxidant or oxidation with an oxidant followed by bromine stripping and absorption with a reducing agent.

[0064] Beneficial effects: The system described in this invention can separate bromine from water and produce usable hydrobromic acid, bromine, and sodium bromide. The bromide ion extraction rate is over 80%. The conversion agent B used in the system is naturally present in the wastewater, reducing operating costs and minimizing the introduction of other ions.

[0065] This system is also applicable to the separation of two or more ions of the same polarity, such as mixed solutions of sodium sulfate and sodium bromide, sodium carbonate and sodium bromide, sodium nitrate and sodium bromide, and sodium chloride and sodium bromide. This method is also applicable to bromine extraction from seawater and brine. The operating principle is the same, and those skilled in the art can derive the usage method based on this patent. Attached Figure Description

[0066] Figure 1This is a system diagram of the extraction of hydrobromic acid from bromine-containing wastewater as described in Embodiment 1 of the present invention;

[0067] Figure 2 This is a system diagram of the extraction of hydrobromic acid from bromine-containing wastewater as described in Embodiment 2 of the present invention;

[0068] Figure 3 This is a system diagram of the extraction of hydrobromic acid from bromine-containing wastewater as described in Embodiment 3 of the present invention;

[0069] Figure 4 This is a system diagram of the extraction of hydrobromic acid from bromine-containing wastewater as described in Embodiment 4 of the present invention.

[0070] In the diagram, 1. Inlet water; 2. Pretreatment system; 3. Bromine ion extraction device; 4. Transforming agent extraction system; 5. Hydrobromic acid extraction system; 6. Filter; 7. Nanofiltration device I; 8. Electrodialysis device I; 9. Crystallization device; 10. Centrifuge; 11. Membrane distillation device; 12. Distillation device; 13. Purification device; 14. Neutralization device; 15. Nanofiltration device II; 16. Electrodialysis device II; 17. Acidification device; 18. Regenerant A; 19. Transforming agent B; 20. Hydrobromic acid; 21. Distilled water; 22. Drainage; 23. Oxidation device; 24. Absorption device. Detailed Implementation

[0071] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the present invention, but do not limit the invention in any way.

[0072] Example 1

[0073] Figure 1 The present invention is a system flowchart. A system for extracting hydrobromic acid from bromine-containing wastewater includes an influent 1, a pretreatment system 2, a bromide ion extraction device 3, a transforming agent extraction system 4, and a hydrobromic acid extraction system 5.

[0074] Inlet 1 is connected to the inlet of pretreatment system 2. The outlet of pretreatment system 2 is connected to the inlet of bromide ion extraction device 3. The debromination outlet of bromide ion extraction device 3 is connected to the inlet of conversion agent extraction system 4. Water is discharged from the outlet of conversion agent extraction system 4, and conversion agent B is extracted from the conversion agent extraction system. The desorption liquid outlet of bromide ion extraction device 3 is connected to the inlet of hydrobromic acid extraction system 5. The hydrobromic acid extraction device 5 has three outlets: distilled water, hydrobromic acid, and regenerator A or an anionic salt of regenerator A.

[0075] The specific implementation method is as follows: Influent 1 first enters pretreatment system 2 to remove suspended solids or substances that may affect subsequent treatment systems (including anions selected before bromide ions, or high levels of metal ions such as copper, iron, and chromium, which can poison the resin and reduce its activity), ensuring stable operation of the subsequent system. The effluent from pretreatment system 2 enters bromide ion extraction device 3. When bromide ion extraction device 3 uses a macroporous strong-base anion exchange resin, it adsorbs bromide ions from the water. After adsorption saturation, regenerator A is used for desorption, removing the adsorbed bromide ions. When sulfuric acid is used as regenerator A, the desorbed solution A consists of sulfuric acid and hydrobromic acid. Desorbed solution A passes through a hydrobromic acid extraction system to separate the sulfuric acid and hydrobromic acid, ultimately yielding hydrobromic acid which can be reused in production, and sulfuric acid which is reused as regenerator A. The effluent from bromide ion extraction device 3 enters conversion agent extraction system 4, where conversion agent B is extracted from the water for resin conversion. The wastewater from the transformation agent extraction system 4 is discharged into the wastewater treatment plant. When the wastewater is mainly composed of sodium bicarbonate, the transformation agent B extracted by the transformation agent extraction system is sodium bicarbonate.

[0076] After the bromide ion extraction device 3 desorbs the bromide ions adsorbed on it using regenerator A, the device is in the sulfuric acid form. It is then converted to the bicarbonate form using sodium bicarbonate (a conversion agent B extracted from wastewater). Thus, when the bromide ion extraction device 3 enters its working state, it selectively adsorbs bromide ions and no longer adsorbs bicarbonate ions from the water.

[0077] Example 2

[0078] according to Figure 2 This document details one embodiment of the present invention. This embodiment uses bromine-containing gaseous wastewater generated during PTA production as an example; the treatment principle is the same for other types of bromine-containing wastewater. Those skilled in the art can use this principle to extract bromide ions and produce hydrobromic acid, bromine, and sodium bromide, simply by considering the selection of regenerator A and transformant B and performing relevant pretreatment on the wastewater.

[0079] Taking the bromine-containing gaseous wastewater (PTA oxidation tail gas alkaline absorption wastewater) generated during PTA production as an example, its main components are: sodium bicarbonate 15 g / L, sodium carbonate 3.5 g / L, sodium bromide 1.5 g / L, sodium formate 0.6 g / L, and sodium acetate 0.3 g / L. Sodium bicarbonate has the highest proportion in the raw water, reaching 71.8%. Therefore, the bromide ion extraction unit 3 uses a bicarbonate-type macroporous strong-base anion exchange resin. The conversion agent B is sodium bicarbonate, and the regenerator A is sulfuric acid.

[0080] Pretreatment system 2 uses filter 6;

[0081] The bromide ion extraction device 3 uses a bicarbonate-type macroporous strong base anion exchange resin (such as D201).

[0082] The transformation agent extraction system 4 includes a nanofiltration device I 7, an electrodialysis device I 8, a crystallization device 9, and a centrifuge 10;

[0083] The hydrobromic acid extraction system 5 includes a membrane distillation device 11, a distillation device 12, and a purification device 13.

[0084] The implementation method is as follows: Water inlet 1 is connected to the inlet of filter 6, where suspended solids are removed. The outlet of filter 6 is connected to the inlet of bromide ion extraction device 3, where bromide ions are selectively adsorbed onto the bicarbonate-type macroporous strong-base anion exchange resin. The debromination outlet of bromide ion extraction device 3 is connected to the inlet of nanofiltration device I 7, where organic matter such as formic acid and acetic acid, as well as divalent and higher-valent ions such as calcium, magnesium, copper, and iron, are removed. The outlet of nanofiltration device I 7 is connected to the inlet of electrodialysis device I 8, where the water is concentrated, and the electrodialysis permeate is discharged into a wastewater treatment plant. The concentrated water outlet of electrodialysis device I 8 is connected to crystallization device 9, where solid sodium bicarbonate is extracted through low-temperature (60°C) crystallization. The extracted solid sodium bicarbonate enters centrifuge 10 to remove excess water. The obtained solid sodium bicarbonate is used as a transforming agent B.

[0085] After the bromide ion extraction unit 3 becomes saturated, it is first desorbed using regenerator A (sulfuric acid). Desorption solution A is a mixture of sulfuric acid and hydrobromic acid. Desorption solution A is then concentrated in membrane distillation unit 11. The concentrated solution from membrane distillation unit 11 is then distilled in distillation unit 12 to obtain hydrobromic acid, distilled water, and concentrated sulfuric acid. The distilled water produced during the concentration process in membrane distillation unit 11 and distillation in distillation unit 12 is either used to prepare regenerator or discharged directly. The concentrated sulfuric acid obtained from distillation in distillation unit 12 is used to prepare regenerator A. The obtained hydrobromic acid is then purified in purification unit 13, where a small amount of bromine produced during distillation is adsorbed and can be used as a product or reused in production. Purification unit 13 uses a bromine-type strong-base anion exchange resin (such as D201).

[0086] When the bromide ion extraction device 3 is regenerated by regenerator A and then transformed by transforming agent B to convert the resin into the bicarbonate type, the resulting desorption liquid B contains sulfate but no organic matter and can be discharged directly, or treated in the aerobic section of the sewage treatment plant before being discharged.

[0087] Example 3

[0088] according to Figure 3Another embodiment of the present invention will be described in detail below. Taking the influent, which is bromine-containing gaseous wastewater generated during PTA production, as an example, its main components are: sodium bicarbonate 15 g / L, sodium carbonate 3.5 g / L, sodium bromide 1.5 g / L, sodium formate 0.6 g / L, and sodium acetate 0.3 g / L. Sodium bicarbonate accounts for the highest proportion in the raw water, reaching 71.8%. The bromide ion extraction device 3 uses a bicarbonate-type macroporous strong basic anion exchange resin. The conversion agent B is sodium bicarbonate, and the regenerator A is sulfuric acid.

[0089] Pretreatment system 2 uses filter 6;

[0090] The bromide ion extraction device 3 uses a bicarbonate-type macroporous strong base anion exchange resin.

[0091] The transformation agent extraction system 4 includes a nanofiltration device I 7, an electrodialysis device I 8, a crystallization device 9, and a centrifuge 10;

[0092] The hydrobromic acid extraction system 5 includes a neutralization device 14, a nanofiltration device II 15, an electrodialysis device II 16, an acidification device 17, a distillation device 12, and a purification device 13;

[0093] The acidification device uses a strong acid cation exchange resin (such as 001×7).

[0094] The implementation method is as follows: Water inlet 1 is connected to the inlet of filter 6, where suspended solids are removed. The outlet of filter 6 is connected to the inlet of bromide ion extraction device 3, where bromide ions are selectively adsorbed onto the bicarbonate-type macroporous strong-base anion exchange resin. The debromination outlet of bromide ion extraction device 3 is connected to the inlet of nanofiltration device I 7, where organic matter such as formic acid and acetic acid, as well as divalent and higher-valent ions such as calcium, magnesium, copper, and iron, are removed. The outlet of nanofiltration device I 7 is connected to the inlet of electrodialysis device I 8, where the water is concentrated, and the electrodialysis permeate is discharged into a wastewater treatment plant. The concentrated water outlet of electrodialysis device I 8 is connected to crystallization device 9, where solid sodium bicarbonate is extracted through low-temperature (60°C) crystallization. The extracted solid sodium bicarbonate enters centrifuge 10 to remove excess water. The obtained solid sodium bicarbonate is used as a transforming agent B.

[0095] After the bromide ion extraction unit 3 becomes saturated, it is first desorbed using regenerator A (sulfuric acid). The desorbate A is a mixture of sulfuric acid and hydrobromic acid. Desorbate A enters the neutralization unit 14, where sodium bicarbonate extracted from the regenerator recovery system 4 is added for neutralization. The neutralized solution is a mixture of sodium sulfate and sodium bromide. The permeate from the neutralization enters the nanofiltration unit II 15, which separates the sodium sulfate and bromide in the water. The resulting sodium bromide solution enters the electrodialysis unit II 16 for concentration, yielding a higher concentration sodium bromide solution. The sodium sulfate solution separated by the nanofiltration unit II 15 can be directly discharged or treated in the aerobic section of a wastewater treatment plant. The permeate from the electrodialysis unit II 16 is reused in the system. When the sulfate concentration is high (greater than 80 g / L) and reaches the upper limit of nanofiltration operation, the permeate is diluted for use in the nanofiltration feed water. Excess permeate from the electrodialysis unit II 16 is discharged into the wastewater treatment plant. The concentrated water from the electrodialysis unit II 16 enters the acidification unit 17, where sodium ions in the water are converted into hydrogen ions. The hydrobromic acid solution produced by acidification unit 17 enters distillation unit 12 for distillation. Based on the boiling point of hydrobromic acid, a hydrobromic acid solution meeting production requirements is distilled (the effluent above 128℃ is 48% hydrobromic acid). The obtained hydrobromic acid enters purification unit 13, where the small amount of bromine produced during distillation is adsorbed and can be used as a product or reused in production. Purification unit 13 uses a bromine-type strong basic anion exchange resin. The small amount of residual liquid from distillation is returned to the front end of the system (inlet water 1) or recycled to desorption liquid A.

[0096] Example 4

[0097] according to Figure 4 This document details one embodiment of the present invention. This embodiment uses bromine-containing gaseous wastewater generated during PTA production as an example; the treatment principle is the same for other types of bromine-containing wastewater. Those skilled in the art can use this principle to extract bromide ions and produce hydrobromic acid, bromine, and sodium bromide, simply by considering the selection of regenerator A and transformant B and performing relevant pretreatment on the wastewater.

[0098] Taking the bromine-containing gaseous wastewater (PTA oxidation tail gas alkaline absorption wastewater) generated during PTA production as an example, its main components are: sodium bicarbonate 15 g / L, sodium carbonate 3.5 g / L, sodium bromide 1.5 g / L, sodium formate 0.6 g / L, and sodium acetate 0.3 g / L. Sodium bicarbonate has the highest proportion in the raw water, reaching 71.8%. Therefore, the bromide ion extraction unit 3 uses a bicarbonate-type macroporous strong-base anion exchange resin. The conversion agent B is sodium bicarbonate, the regenerator A is hydrochloric acid, the oxidant is sodium hypochlorite, and the reducing agent is formic acid.

[0099] Pretreatment system 2 uses filter 6;

[0100] The bromide ion extraction device 3 uses a bicarbonate-type macroporous strong base anion exchange resin (such as D201).

[0101] The transformation agent extraction system 4 includes a nanofiltration device I7 and an electrodialysis device I8;

[0102] The hydrobromic acid extraction system 5 includes an oxidation device 23, an absorption device 24, a distillation device 12, and a purification device 13.

[0103] The specific implementation method is as follows: Water inlet 1 is connected to the inlet of filter 6, where suspended solids are removed. The outlet of filter 6 is connected to the inlet of bromide ion extraction device 3, where bromide ions are selectively adsorbed onto the bicarbonate-type macroporous strong-base anion exchange resin. The outlet of bromide ion extraction device 3 is connected to the inlet of nanofiltration device I 7, where organic matter such as formic acid and acetic acid, as well as divalent and higher-valent ions such as calcium, magnesium, copper, and iron, are removed. The outlet of nanofiltration device I 7 is connected to the inlet of electrodialysis device I 8, where the water is concentrated, and the electrodialysis permeate is discharged into the wastewater treatment plant. The sodium bicarbonate solution obtained from the outlet of electrodialysis device I 8 is used as a transforming agent B.

[0104] After the bromide ion extraction device 3 becomes saturated, it is first desorbed using regenerator A (hydrochloric acid). The desorption solution A is a mixture of hydrochloric acid and hydrobromic acid. Desorption solution A enters oxidation device 23, where sodium hypochlorite is added as an oxidant to oxidize bromide ions in the water to bromine. The bromine is then stripped off by air and enters the reduction device, i.e., absorption device 24. The residue after bromine is stripped from oxidation device 23 can be directly reused as regenerator A. If oxidant residue remains in the residue, a reducing agent can be added for reduction before reuse as regenerator A. Formic acid is added to the reduction device as a reducing agent to absorb bromine, generating hydrobromic acid and carbon dioxide. The carbon dioxide is discharged from absorption device 24. The resulting hydrobromic acid solution is distilled in distillation device 12 to obtain hydrobromic acid, distilled water, and formic acid. The distilled water is sent to inlet 1 for use in preparing regenerator or directly discharged. The formic acid obtained from distillation in device 12 is returned to absorption device 24 as a reducing agent. The obtained hydrobromic acid enters purification unit 13, where a small amount of bromine produced during distillation is adsorbed and can be used as a product or reused in production. Purification unit 13 uses a bromine-type strong basic anion exchange resin (such as D201). The "residual liquid" refers to the liquid remaining after the bromine is stripped from the oxidation unit.

[0105] After being regenerated by regenerator A, bromide ion extraction device 3 uses conversion agent B to convert the resin to the bicarbonate form. The resulting desorption liquid B is then treated in the aerobic section of the wastewater treatment plant before being discharged.

[0106] For anyone skilled in the art, many possible variations and modifications can be made to the technical solutions of this invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the technical solutions of this invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this invention without departing from the content of the technical solutions of this invention should still fall within the protection scope of the technical solutions of this invention.

Claims

1. A treatment method for extracting hydrobromic acid from bromine-containing wastewater, characterized by, The bromine-containing wastewater is connected with a pretreatment system (2), a bromide ion extraction device (3), and a hydrobromic acid extraction system (5) in sequence; the pretreatment system (2) comprises a filter; the bromide ion extraction device (3) comprises an anion exchange resin; the anion exchange resin exchange group is an anion with a large content in the wastewater and competitive with bromide ions, and is used for selectively adsorbing bromide ions in water; the hydrobromic acid extraction system comprises a bromine separation device and a purification device; The bromide ion extraction device (3) is also connected with a transformation agent extraction system (4); the transformation agent extraction system (4) comprises an organic matter removal device, a divalent cation removal device, and a concentration device; A treatment method for extracting hydrobromic acid from bromine-containing wastewater, wherein the competitive anion species in the wastewater, except for bromide ions, is one or two, or the content of the other competitive anions is less than 100 mg / L, and the wastewater is gas-phase bromine-containing wastewater generated in a PTA production process, and the method comprises the following steps: 1) The bromine-containing wastewater is subjected to a pretreatment system (2) to remove suspended solids in the water; 2) The wastewater enters a bromide ion extraction device (3), and under the action of an anion exchange resin, bromide ions in the water are selectively adsorbed onto the resin; the bromide ion extraction device (3) is connected with a transformation agent extraction system (4); in the transformation agent extraction system (4), after organic matter removal, divalent cation removal, concentration, or after organic matter removal, divalent cation removal, concentration, crystallization, and solid-liquid separation, a transformation agent B is obtained; 3) When the bromide ion extraction device (3) is saturated, a regenerant A is added to the bromide ion extraction device (3) to desorb the bromide ions, forming a desorption liquid containing the regenerant A and the bromide ions; the desorption liquid is separated into the regenerant A and the bromide ions by a bromine separation device; the separated bromide ions enter a purification device for purification; and the regenerant A is recycled; 4) After the desorption in step 3) is completed, the transformation agent B obtained in step 2) is added to the bromide ion extraction device (3) to convert the anion exchange resin exchange group into an anion exchange group that is competitive with bromide ions in the wastewater to be treated, and is used for cyclic treatment of the bromine-containing wastewater; The transformation agent B is an anion salt with a large content in water and competitive with bromide ions, and includes sodium carbonate, sodium bicarbonate, or sodium hydroxide; and the regenerant A is a compound that can desorb bromide ions from the resin and can be separated from the bromide ions, and includes sulfuric acid, hydrochloric acid, nitric acid, sodium benzoate, or sodium citrate.

2. The process for extracting hydrobromic acid from a bromine-containing wastewater according to claim 1, characterized by, The filter comprises a precision filter or a bag filter; and the anion exchange resin comprises a strong base type, a weak base type, a macroporous type, or a gel type resin.

3. The process for extracting hydrobromic acid from a bromine-containing wastewater according to claim 1, characterized by, The organic matter removal device comprises a nanofiltration device, a microfiltration device, an electro-oxidation device, a biochemical device, or an activated carbon device; the divalent cation removal device comprises a nanofiltration device or an ion exchange resin; and the concentration device comprises an electro-dialysis device, a reverse osmosis device, or an evaporation device.

4. The process for extracting hydrobromic acid from a bromine containing waste water as claimed in claim 1 wherein, The concentration device is sequentially connected with a crystallization device and a solid-liquid separation device; the crystallization device comprises a freeze crystallization device or an evaporation crystallization device; and the solid-liquid separation device comprises a centrifuge or a filter press.

5. The process as claimed in claim 1, wherein the process for extracting hydrobromic acid from the bromine containing waste water is characterized by, The bromine separation device comprises a combination of concentration device and distillation device, a membrane separation device, or a combination of neutralization device and separation device; the separation device comprises a nanofiltration device or an ion exchange resin; the purification device comprises a combination of evaporation device and purification device or a distillation device.

6. The process for extracting hydrobromic acid from a bromine-containing wastewater according to claim 5, characterized by, When the bromine separation device is a combination of neutralization device and separation device, a concentration device and / or an acidification device are connected after the separation device, and then connected with the purification device; the concentration device comprises an electrodialysis device, a reverse osmosis device, an evaporator, a membrane distillation device or an electrostatic adsorption device; the acidification device comprises a hydrogen type cation exchange resin or a bipolar membrane; the purification device comprises an ion exchange resin, activated carbon or an extraction device; the neutralization agent selected for the neutralization device is an alkaline compound, including sodium hydroxide, sodium carbonate or sodium bicarbonate.

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