System for extracting hydrobromic acid from bromine-containing wastewater and treatment method thereof

Abstract

The invention 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. Comprising a pretreatment system, a bromide ion extraction device, a regenerant extraction system and a hydrobromic acid extraction system. The bromine ion extraction device adopts ion exchange resin, and bromine in water can be selectively extracted. The regenerant 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. According to the system, anion salt which is high in content and competitive with bromide ions is extracted from water to serve as a transformation agent B, resin is transformed, so that the resin selectively adsorbs the bromide ions in the water, the bromide ions in the water are enriched, the saturated bromide ions are desorbed into desorption liquid through regeneration A, and the water quality is improved. And separating and purifying the regenerant A and bromide ions, or acidifying and purifying to obtain a pure hydrobromic acid solution.

Description

Technical Field

[0001] The present invention relates to a sewage treatment system and a treatment method, and particularly to a system for extracting hydrobromic acid from bromine-containing wastewater and its treatment method, belonging to the field of industrial wastewater treatment, and applicable to the treatment of industrial bromine-containing wastewater, bromine extraction from seawater and brine. Background Art

[0002] As an important chemical raw material, hydrobromic acid is widely used in the fields of fine chemicals, petrochemicals, pharmaceuticals, agriculture, etc. However, enterprises using hydrobromic acid as a production raw material all have problems of affecting drainage due to excessive bromide ions, and at the same time, the price of hydrobromic acid has been rising, resulting in higher and higher production costs.

[0003] The presence of bromide ions in water will affect the effect of biochemical treatment, and at the same time, if the drainage contains bromide ions, it will also affect the detection of COD, resulting in the effluent COD value being higher than the normal value. As an important chemical raw material, if bromine is extracted from water, it can not only reduce production costs, but also reduce the pressure of wastewater treatment.

[0004] For example, in the PTA (purified terephthalic acid) production industry, generally p-xylene is used as a raw material, cobalt and manganese are used as catalysts, and air oxidation is carried out in an acetic acid medium to produce crude terephthalic acid (CTA). Then, the crude terephthalic acid is subjected to hydrogenation refining to remove impurities, and then through crystallization, separation, drying, to obtain purified terephthalic acid products, that is, PTA finished products. Because hydrobromic acid is also added to participate in the reaction during the production process, the bromine-containing wastewater generated is mainly divided into: gaseous bromine-containing wastewater - wastewater generated by absorbing tail gas with alkali solution; liquid-phase bromine-containing wastewater - waste liquid containing a large amount of organic matter and residues after the reaction.

[0005] The gaseous wastewater mainly contains sodium formate, sodium acetate, sodium bromide, sodium carbonate, sodium bicarbonate and contains a small amount of oxidants. The liquid-phase wastewater mainly contains sodium acetate, aromatic organic matter, sodium bromide, sodium bicarbonate.

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

[0007] If the bromide ions in water are extracted to make hydrobromic acid and recycled to production, it can not only greatly reduce production costs but also improve the drainage water quality. Summary of the Invention

[0008] In order to solve the problems existing in the prior art, the present invention provides a system for extracting hydrobromic acid from bromine-containing wastewater and its treatment method.

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

[0010] The present invention is applicable to the treatment of bromine-containing wastewater with few other anionic species except bromide ions (the other competing anionic species in the water except bromide ions are one or two, or the content of the excess other competing anions is less than 100 mg / L). When the wastewater treatment system is complex and there are many anionic species, some anions need to be removed in advance according to the selectivity of the resin, and one or two anions are retained, and the retained anions are selected as the exchange groups. If there are other substances affecting the treatment in the water, pretreatment is also required to remove them.

[0011] The core of the present invention lies in using a resin with a relatively large content of competing anions except bromide ions in the water as the exchange group, so that the resin can selectively adsorb bromide ions in the water. At the same time, the homonymous anion salt in the water as the exchange group is extracted as the transformation agent B to transform the resin, so that the resin can selectively adsorb bromide ions, and at the same time, the use cost of the regenerant is saved.

[0012] Furthermore, by selecting a regenerant A that is easy to separate from bromide ions to desorb the bromide ions adsorbed on the resin, and then separating the regenerant A from the bromide ions in the desorption solution. Finally, the extraction of bromide ions from the wastewater is realized. The extracted bromide ions can be used to produce bromine, sodium bromide or hydrobromic acid. In the present invention, it is preferably to produce hydrobromic acid.

[0013] The present invention provides a system for extracting hydrobromic acid from bromine-containing wastewater, and 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 an anion exchange resin; the exchange group of the anion exchange resin is an anion with a large content in the treated wastewater and competitive with bromide ions, and is 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 regenerant extraction system; the regenerant 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 in the water to protect the stable operation of the subsequent system. The filter includes, but is not limited to, sand filters, precision filters, bag filters, ultrafiltration or microfiltration and other devices or systems that can achieve the same filtration purpose.

[0019] Further, if there are other substances affecting the water, such as a large variety of anions or high-concentration organic substances, etc., they need to be removed in advance. A nanofiltration device, an AO reaction tank, and a chemical reagent dosing device are provided in front of the filter; specifically, it includes separating large-molecule organic substances, divalent and higher-valent ions through the nanofiltration device, or removing organic substances in the water through biochemical treatment, or removing anionic salts such as phosphates and sulfates in the water by adding chemical reagents, or other relevant technical means for treatment before entering the filter for treatment.

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

[0021] Further, 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] Further, the regenerant extraction system extracts an anionic salt (such as sodium bicarbonate) with a large content in the water and competitive with bromide ions as the regenerant for use. When sodium bicarbonate is the main component in the water, the regenerant extracted by the regenerant extraction system is sodium bicarbonate.

[0023] Further, the regenerant extracted by the regenerant extraction system can be in liquid form, with a concentration required for the regeneration of the bromide ion extraction device. It can also extract the solid conversion agent B. When the extracted conversion 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 evaporation crystallization device or a freeze crystallization device, etc. The solid-liquid separation device includes but is not limited to a centrifuge or a filter press, etc.

[0024] Further, the organic substance removal device in the regenerant extraction system includes but is not limited to a nanofiltration device, a microfiltration device, an electrooxidation device, a biochemical device, activated carbon, and other devices or systems that can remove organic substances in the water. Preferably, a nanofiltration device is used. Removing organic substances is to ensure that the desorption liquid does not contain organic substances, ensure the purity of the extracted hydrobromic acid, and at the same time, it can also classify and discharge according to whether there are organic substances in the drainage.

[0025] Further, the organic substance removal device includes but is not limited to a nanofiltration device, a microfiltration device, an electrooxidation device, a biochemical device or an activated carbon device. The organic substance removal device is used to remove the organic substances mixed in the conversion agent B, and it can be placed before the concentration device or after the concentration of the concentration device. After the concentration device produces the conversion agent B, it is reused after removing the organic substances in the water through the organic substance removal device, or after passing through the crystallization device and the centrifuge to extract the solid conversion agent B and then reused.

[0026] Further, the divalent cation removal device includes, but is not limited to, a nanofiltration device or a cation exchange resin, etc., which can remove divalent and higher ions in water. Preferably, a nanofiltration device or an ion exchange resin is used. If a nanofiltration device is selected for the organic matter removal device to separate organic matter, the divalent cation removal device can remove it. Through the previous nanofiltration device, organic matter and divalent and higher ions in water can be removed simultaneously. If the organic matter removal device is placed after the concentrated water of the concentration device, it is preferably to use ion exchange to remove divalent and higher cations.

[0027] Further, the concentration device includes, but is not limited to, an electrodialysis device, a reverse osmosis device or an evaporation device, etc., which can concentrate water. Preferably, an electrodialysis device is used.

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

[0029] Further, the function of the bromine separation device is to separate the regenerant A and bromide ions in the desorption liquid 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 that can separate the regenerant A and bromide ions. The separation device includes a nanofiltration device or an ion exchange resin.

[0030] Further, the purification device includes a distillation device or a combination of a distillation device and a purification device or a combination of an evaporation device and a purification device, or other devices or systems that can purify hydrobromic acid.

[0031] Further, the purification device is used to improve the product purity and can remove a small amount of bromine contained in hydrobromic acid. If the requirement for product purity is relatively low, the purification device may not be provided.

[0032] Further, the bromine separation device preferably adopts a combination of a concentration device and a distillation device. After the desorption liquid A is concentrated by the concentration device, it then enters the distillation device, and hydrobromic acid in water is distilled out according to the difference in boiling points of each component of the solution. The distilled water produced by distillation can be used for the preparation of the regenerant or directly discharged. The concentrated sulfuric acid at the bottom of the distillation can be reused as the regenerant A. The concentration device includes, but is not limited to, an evaporator, a membrane distillation device, electrostatic adsorption, etc., which can achieve the purpose of concentrating the desorption liquid A. Its purpose is to reduce the amount of distillation. If the concentration device is not used, direct distillation is also feasible.

[0033] Further, the bromine separation device can also adopt a membrane separation device. The membrane separation device can be a pressure-driven membrane such as acid-resistant nanofiltration and reverse osmosis. For example, an acid-resistant membrane separates sulfuric acid and hydrobromic acid, and the separated hydrobromic acid is further purified by distillation to obtain industrial concentrated hydrobromic acid that meets the use requirements. The separated sulfuric acid is used as the regenerant A and recycled in the system.

[0034] Further, the bromine separation device can also adopt a combination of a neutralization device and a separation device. Among them, the separation device is used to separate sulfate radicals and bromide ions in water. When a nanofiltration device is selected as the bromine separation device, the regeneration liquid A needs to be adjusted to the allowable range of the nanofiltration device (pH > 4) by the neutralization device first. The alkali used for neutralization is preferably the transformation agent B extracted from the regeneration agent extraction system (when the transformation 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, and then industrial-grade concentrated hydrobromic acid solution can be obtained through distillation. The sodium bromide solution can also be directly concentrated without acidification to obtain a high-concentration sodium bromide solution, or evaporated and crystallized to obtain sodium bromide solid.

[0035] Further, when the bromine separation device is a combination of a neutralization device and a separation device, a concentration device and / or an acidification device are connected after the separation device, and then connected to the purification device; the concentration device includes an electrodialysis device, a reverse osmosis device, an evaporator, a membrane distillation device, an electrostatic adsorption device, etc., which are devices or systems that can achieve the purpose of concentrating the sodium bromide solution, and its purpose is to reduce the treatment volume.

[0036] Further, the acidification device includes, but is not limited to, a hydrogen-type cation exchange resin or a bipolar membrane, etc., which are devices or systems that can convert sodium bromide into hydrobromic acid. Preferably, a hydrogen-type ion exchange resin is used.

[0037] Further, the bromine separation device includes an oxidation device, an absorption device, and a distillation device connected in sequence. The oxidation device oxidizes bromide ions into bromine by adding an oxidant, and then separates them by stripping or distillation; the absorption device absorbs bromine by adding a reductant, and after being purified by the purification device, bromine or hydrobromic acid is obtained, and then the acid solution obtained after separating bromide ions is used as the regeneration agent A; the oxidants include chlorine, hydrogen peroxide, hypochlorous acid, sodium hypochlorite, concentrated sulfuric acid, etc.; the reductants include sulfur dioxide, formic acid, sodium formate, sodium thiosulfate, sulfurous acid.

[0038] Further, the obtained bromine can be used to produce related products such as hydrobromic acid.

[0039] Further, the purification device includes, but is not limited to, ion exchange resins, activated carbon, extraction devices, etc., which are devices or systems that can adsorb bromine.

[0040] Further, the neutralizing agents selected for the neutralization device include sodium hydroxide, sodium carbonate, or sodium bicarbonate.

[0041] The present invention also provides a treatment method for extracting hydrobromic acid from bromine-containing wastewater, including the following steps:

[0042] 1) The bromine-containing wastewater is pretreated by a pretreatment system to remove suspended solids in the water;

[0043] 2) It enters the bromide ion extraction device, and under the action of anion exchange resin, the bromide ions in the water are selectively adsorbed onto the resin. The de-brominated effluent of the bromide ion extraction device enters the regenerant extraction system. In the regenerant extraction system, after organic matter removal, divalent cation removal, concentration, or after organic matter removal, divalent cation removal, concentration, crystallization, and solid-liquid separation, the transformation agent B is obtained;

[0044] 3) When the bromide ion extraction device is saturated with adsorption, the regenerant A is added to the bromide ion extraction device to desorb the bromide ions, forming a desorption solution containing the regenerant A and hydrobromic acid. The desorption solution is separated into the regenerant A and hydrobromic acid by a bromine separation device, and the separated hydrobromic acid enters a purification device for purification; the regenerant A is recycled;

[0045] Or, the desorption solution containing the regenerant A and bromide ions described in step S3 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 reduction agent absorption;

[0046] 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 to convert the exchange group of the anion exchange resin into an anion exchange group that competes with bromide ions in the waste liquid to be treated, for recycling the treatment of bromine-containing wastewater.

[0047] Furthermore, the transformation agent B is preferably a salt with a large content in water and having a competitive relationship with bromide ions. When the wastewater is the gaseous bromine-containing wastewater (oxidation tail gas caustic absorption wastewater) generated in the PTA production process and the alkalinity in the water mainly exists in the form of sodium bicarbonate, the transformation agent B is sodium bicarbonate at this time. The transformation agent B includes sodium carbonate, sodium bicarbonate, sodium hydroxide, sodium chloride, or sodium sulfate.

[0048] Furthermore, the regenerant A includes compounds such as sulfuric acid, hydrochloric acid, nitric acid, sodium benzoate, sodium phenolate, or sodium citrate that can desorb bromide ions from the resin and can be separated from bromide ions (such as organic substances, inorganic substances, acids, bases).

[0049] Furthermore, the regenerant A is preferably sulfuric acid or hydrochloric acid.

[0050] Furthermore, when sulfuric acid is selected as the regenerant A, the desorption solution mainly coexists in the form of sulfuric acid and hydrobromic acid.

[0051] Furthermore, the desorption solution A enters the bromine separation device to separate sulfuric acid and hydrobromic acid, and the obtained hydrobromic acid solution enters a distillation device to obtain a hydrobromic acid solution through distillation.

[0052] Furthermore, when the anion exchange resin is regenerated, regeneration agent A is first used to desorb bromide ions, and then conversion agent B is used to convert it into a working state. When the resin is saturated with bromide ions, regeneration agent A is first used to replace the bromide ions on the resin. The resulting desorption liquid A enters the hydrobromic acid extraction system, and then conversion agent B is used to convert the resin exchange groups into competitive anion groups in the waste liquid to be treated, ensuring that the resin mainly adsorbs bromide ions during operation and increasing the working exchange capacity. Regeneration agent A is preferably sulfuric acid, or hydrochloric acid, nitric acid, sodium benzoate, sodium citrate, etc., which can replace bromide ions on the resin and can subsequently be separated. Organic matter, inorganic matter, acid, or base as regeneration agent A. Conversion agent B is preferably a salt with a large content in water and competitive with bromide ions. When the water is mainly sodium bicarbonate, conversion agent B is sodium bicarbonate.

[0053] Furthermore, when the anion exchange resin is regenerated, a regeneration agent A and a conversion agent B are selected. When the resin is saturated with bromide ions, the regeneration agent A is first used to desorb the bromide ions on the resin. The resulting desorption liquid A enters the hydrobromic acid extraction system, and then the conversion agent B is used to convert the resin exchange groups into competitive anion groups in the waste liquid to be treated, thereby ensuring that the resin mainly adsorbs bromide ions during operation and improving the working exchange capacity.

[0054] Beneficial Effects: The system described in the invention can separate bromine from water and produce usable hydrobromic acid, bromine, and sodium bromide. The bromide ion extraction rate exceeds 80%. The conversion agent B used in the system is naturally present in the wastewater, reducing operating costs and the amount of other ions introduced.

[0055] This system is also applicable to the separation of two or more other like ions, such as a mixed solution of sodium sulfate and sodium bromide, a mixed solution of sodium carbonate and sodium bromide, a mixed solution of sodium nitrate and sodium bromide, etc. The operating principle is the same, and those skilled in the art can deduce the usage method based on this patent. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 This is a system diagram for extracting hydrobromic acid from bromine-containing wastewater as described in Example 1 of the present invention;

[0057] Figure 2 This is a system diagram for extracting hydrobromic acid from bromine-containing wastewater as described in Example 2 of the present invention;

[0058] Figure 3 This is a system diagram for extracting hydrobromic acid from bromine-containing wastewater as described in Example 3 of the present invention;

[0059] Figure 4 This is a system diagram for extracting hydrobromic acid from bromine-containing wastewater as described in Example 4 of the present invention.

[0060] In the figure, 1 is the water inlet, 2 is the pretreatment system, 3 is the bromide ion extraction device, 4 is the regenerant extraction system, 5 is the hydrobromic acid extraction system, 6 is the filter, 7 is the nanofiltration device I, 8 is the electrodialysis device I, 9 is the crystallization device, 10 is the centrifuge, 11 is the membrane distillation device, 12 is the distillation device, 13 is the purification device, 14 is the neutralization device, 15 is the nanofiltration device II, 16 is the electrodialysis device II, 17 is the acidification device, 18 is the regenerant A, 19 is the transformation agent B, 20 is the hydrobromic acid, 21 is the distilled water, 22 is the drainage, 23 is the oxidation device, 24 is the absorption device. Detailed implementation mode

[0061] The following non-limiting examples can enable those of ordinary skill in the art to more comprehensively understand the present invention, but do not limit the present invention in any way.

[0062] Example 1

[0063] Figure 1 It is a system flowchart of the present invention. A system for extracting hydrobromic acid from bromine-containing wastewater includes a water inlet 1, a pretreatment system 2, a bromide ion extraction device 3, a regenerant extraction system 4, and a hydrobromic acid extraction system 5.

[0064] The water inlet 1 is connected to the water inlet of the pretreatment system 2. The water outlet of the pretreatment system 2 is connected to the water inlet of the bromide ion extraction device 3. The de-brominated water outlet of the bromide ion extraction device 3 is connected to the water inlet of the regenerant extraction system 4. The water outlet of the regenerant extraction system 4 discharges the water, and at the same time, the transformation agent B is extracted from the regenerant extraction system. The desorption liquid outlet of the bromide ion extraction device 3 is connected to the water inlet of the hydrobromic acid extraction system 5. There are three outlets for the water outlet of the hydrobromic acid extraction device 5, which are distilled water, hydrobromic acid, and regenerant A or the anion salt of regenerant A respectively.

[0065] The specific implementation method is as follows: The influent 1 first enters the pretreatment system 2 to remove suspended solids in the water or substances that affect the subsequent treatment system (including anions whose selection order is before bromide ions, or when the content of metal ions such as copper, iron, and chromium in the water is relatively high, and the metal ions will cause resin poisoning and lead to a decrease in activity), ensuring the stable operation of the subsequent system. The effluent of the pretreatment system 2 enters the bromide ion extraction device 3. When the bromide ion extraction device 3 uses macroporous strongly basic anion exchange resin. The bromide ion extraction device 3 adsorbs bromide ions in the water onto the bromide ion extraction device 3. After the bromide ion extraction device 3 is saturated with adsorption, a regenerant A is used for desorption to desorb the bromide ions adsorbed on the bromide ion extraction device 3. When the regenerant A is sulfuric acid, the desorbed liquid A obtained by desorption consists of sulfuric acid and hydrobromic acid. The desorbed liquid A passes through the hydrobromic acid extraction system to separate sulfuric acid and hydrobromic acid, and finally the product hydrobromic acid can be recycled in production, and sulfuric acid is recycled as the regenerant A. The effluent of the bromide ion extraction device 3 enters the regenerant extraction system 4 to extract the transformation agent B from the water for resin transformation. The produced water of the regenerant extraction system 4 is discharged into the sewage treatment plant. When the wastewater is mainly sodium bicarbonate, the transformation agent B extracted by the regenerant extraction system is sodium bicarbonate.

[0066] After the bromide ion extraction device 3 desorbs the bromide ions adsorbed on the device with the regenerant A, the device is in the sulfuric acid type, and then it is converted to the bicarbonate type with the transformation agent B sodium bicarbonate extracted from the wastewater. In this way, when the bromide ion extraction device 3 enters the working state, it will selectively adsorb bromide ions and no longer adsorb bicarbonate ions in the water.

[0067] Example 2

[0068] According to Figure 2 , one of the implementation methods of the present invention will be described in detail. In this example, the gaseous bromine-containing wastewater generated in the PTA production process is taken as an example for description, and the treatment principles of other types of bromine-containing wastewater are the same. Those skilled in the same profession and the same field can, according to the principles described herein, only need to consider the selection of the regenerant A and the transformation agent B and perform relevant pretreatment on the wastewater to achieve the extraction of bromide ions and the preparation of hydrobromic acid, bromine, and sodium bromide.

[0069] Taking the gaseous bromine-containing wastewater (PTA oxidation tail gas caustic absorption wastewater) generated in PTA production as the influent, the main components of its influent 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%, so the bromide ion extraction device 3 uses bicarbonate-type macroporous strongly basic anion exchange resin. The transformation agent B is sodium bicarbonate, and the regenerant A is sulfuric acid.

[0070] The pretreatment system 2 selects a filter 6;

[0071] The bromide ion extraction device 3 uses a macroporous strongly basic anion exchange resin of the bicarbonate type (such as D201);

[0072] The regenerant extraction system 4 includes a nanofiltration device I 7, an electrodialysis device I 8, a crystallization device 9, and a centrifuge 10;

[0073] The hydrobromic acid extraction system 5 includes a membrane distillation device 11, a distillation device 12, and a purification device 13.

[0074] The specific implementation method is as follows: The influent water 1 is connected to the water inlet of the filter 6. The suspended solids in the water are removed through the filter 6. The water outlet of the filter 6 is connected to the water inlet of the bromide ion extraction device 3. The bromide ions in the water are selectively adsorbed onto the resin by the macroporous strongly basic anion exchange resin of the bicarbonate type. The de-brominated water outlet of the bromide ion extraction device 3 is connected to the water inlet of the nanofiltration device I 7. The organic substances such as formic acid and acetic acid and divalent and above ions such as calcium, magnesium, copper, and iron in the water are removed through the nanofiltration device I. The water outlet of the nanofiltration device I 7 is connected to the water inlet of the electrodialysis device I 8. The water is concentrated through the electrodialysis device I 8, and the electrodialysis-produced water is discharged into the sewage treatment plant. The concentrated water outlet of the electrodialysis device I 8 is connected to the crystallization device 9. Solid sodium bicarbonate is extracted through low-temperature (60 °C) crystallization. The extracted solid sodium bicarbonate enters the centrifuge 10 to discharge the excess water. The obtained solid sodium bicarbonate is used as the transformation agent B.

[0075] When the bromide ion extraction device 3 is saturated with adsorption, first use the regenerant A sulfuric acid to desorb the bromide ion extraction device 3. The desorption liquid A is a mixture of sulfuric acid and hydrobromic acid. The desorption liquid A enters the membrane distillation device 11 for concentration. The concentrated liquid produced by the membrane distillation device 11 enters the distillation device 12 for rectification to obtain hydrobromic acid, distilled water, and concentrated sulfuric acid. The distilled water produced during the concentration process of the membrane distillation device 11 and the distillation of the distillation device 12 is used for the influent water 1 or for preparing the regenerant or directly discharged. The concentrated sulfuric acid obtained by distillation in the distillation device 12 is used for preparing the regenerant A. The obtained hydrobromic acid enters the purification device 13 to adsorb the small amount of bromine produced by distillation and can be used as a product or recycled in production. The purification device 13 selects a bromide-type strongly basic anion exchange resin (such as D201).

[0076] When the bromide ion extraction device 3 is regenerated with the regenerant A and then uses the transformation agent B to transform the resin into the bicarbonate type, the desorption liquid B produced at the same time contains sulfate but no organic substances and can be directly discharged or discharged after being treated in the aerobic section of the sewage treatment plant.

[0077] Example 3

[0078] According to Figure 3, a further embodiment of the present invention will be described in detail. Taking the gaseous bromine-containing wastewater generated in PTA production as the influent water, the main components of the influent water 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 strongly basic anion exchange resin. The transformation agent B is sodium bicarbonate, and the regenerant A is sulfuric acid.

[0079] The pretreatment system 2 selects a filter 6;

[0080] The bromide ion extraction device 3 uses a bicarbonate-type macroporous strongly basic anion exchange resin;

[0081] The regenerant extraction system 4 includes a nanofiltration device I 7, an electrodialysis device I 8, a crystallization device 9, and a centrifuge 10;

[0082] 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;

[0083] The acidification device uses a strongly acidic cation exchange resin (such as 001×7).

[0084] The specific implementation method is as follows: The influent water 1 is connected to the water inlet of the filter 6. The filter 6 removes suspended solids in the water. The water outlet of the filter 6 is connected to the water inlet of the bromide ion extraction device 3. The bicarbonate-type macroporous strongly basic anion exchange resin selectively adsorbs bromide ions in the water onto the resin. The de-brominated water outlet of the bromide ion extraction device 3 is connected to the water inlet of the nanofiltration device I 7. The nanofiltration device I removes organic substances such as formic acid and acetic acid in the water, as well as divalent and higher-valent ions such as calcium, magnesium, copper, and iron. The water outlet of the nanofiltration device I 7 is connected to the water inlet of the electrodialysis device I 8. The electrodialysis device I 8 concentrates the water, and the electrodialysis-produced water is discharged into the sewage treatment plant. The concentrated water outlet of the electrodialysis device I 8 is connected to the crystallization device 9. Solid sodium bicarbonate is extracted by low-temperature (60°C) crystallization. The extracted solid sodium bicarbonate enters the centrifuge 10 to discharge the excess water. The obtained solid sodium bicarbonate is used as the transformation agent B.

[0085] When the bromide ion extraction device 3 is saturated with adsorption, first use the regenerant A sulfuric acid to desorb the bromide ion extraction device 3. The desorption liquid A is a mixture of sulfuric acid and hydrobromic acid. The desorption liquid A enters the neutralization device 14 and is neutralized by adding sodium bicarbonate extracted by the regenerant recovery system 4. After neutralization, it is a mixed solution of sodium sulfate and sodium bromide. The produced water after neutralization enters the nanofiltration device II 15. The nanofiltration device II 15 separates sodium sulfate and bromide in the water. The separated sodium bromide solution enters the electrodialysis device II 16 for concentration to obtain a sodium bromide solution with a higher concentration. The sodium sulfate solution separated by the nanofiltration device II 15 can be directly discharged or enter the aerobic section of the sewage treatment plant for treatment. The produced water of the electrodialysis device II 16 is used for reuse in the system. When the sulfate ion concentration is relatively high (greater than 80 g / L) and reaches the upper limit of nanofiltration operation, it is used to dilute the nanofiltration influent. The excess produced water of the electrodialysis device II 16 is discharged into the sewage treatment plant. The concentrated water of the electrodialysis device II 16 enters the acidification device 17 to convert the sodium ions in the water into hydrogen ions. The hydrobromic acid solution produced by the acidification device 17 enters the distillation device 12 for distillation. According to the boiling point of hydrobromic acid, the hydrobromic acid solution meeting the production requirements is distilled out (the effluent above 128 °C is 48% hydrobromic acid). The obtained hydrobromic acid enters the purification device 13 to adsorb a small amount of bromine produced by distillation and can be used as a product or reused in production. The purification device 13 selects bromine-type strongly basic anion exchange resin. The remaining small amount of bottom liquid after distillation is returned to the front end of the system (inlet water 1) or returned to the desorption liquid A for cyclic treatment.

[0086] Example 4

[0087] According to Figure 4 , one implementation mode of the present invention will be described in detail. This example is described by taking the gaseous bromine-containing wastewater generated in the PTA production process as an example, and the treatment principles of other types of bromine-containing wastewater are the same. Those skilled in the same profession and the same field can, according to the principles described herein, only need to consider the selection of the regenerant A and the transformation agent B and perform relevant pretreatment on the wastewater to achieve the extraction of bromide ions and the preparation of hydrobromic acid, bromine, and sodium bromide.

[0088] Taking the gaseous bromine-containing wastewater (PTA oxidation tail gas caustic absorption wastewater) generated in PTA production as the influent water, the main components of the influent water 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. The proportion of sodium bicarbonate in the raw water is the highest, reaching 71.8%. Therefore, the bromide ion extraction device 3 uses a bicarbonate-type macroporous strongly basic anion exchange resin. The transformation agent B is sodium bicarbonate, the regenerant A is hydrochloric acid, the oxidant is sodium hypochlorite, and the reducing agent is formic acid.

[0089] The pretreatment system 2 selects the filter 6;

[0090] The bromide ion extraction device 3 uses a bicarbonate-type macroporous strongly basic anion exchange resin (such as D201);

[0091] The regenerant extraction system 4 includes a nanofiltration device I 7 and an electrodialysis device I 8;

[0092] The hydrobromic acid extraction system 5 includes an oxidation device 23, an absorption device 24, a distillation device 12, and a purification device 13.

[0093] The specific implementation method is as follows: The influent water 1 is connected to the water inlet of the filter 6. The filter 6 removes the suspended solids in the water. The water outlet of the filter 6 is connected to the water inlet of the bromide ion extraction device 3. The bromide ions in the water are selectively adsorbed onto the resin by the bicarbonate-type macroporous strongly basic anion exchange resin. The water outlet of the bromide ion extraction device 3 is connected to the water inlet of the nanofiltration device I 7. The nanofiltration device I removes organic substances such as formic acid and acetic acid and divalent and higher-valent ions such as calcium, magnesium, copper, and iron in the water. The effluent of the nanofiltration device I 7 is connected to the water inlet of the electrodialysis device I 8. The water is concentrated by the electrodialysis device I 8, and the electrodialysis-produced water is discharged into the sewage treatment plant. The sodium bicarbonate solution obtained from the water outlet of the electrodialysis device I 8 is used as the transformation agent B.

[0094] When the bromide ion extraction device 3 is saturated by adsorption, the regenerant A hydrochloric acid is first used to desorb the bromide ion extraction device 3, and the desorption liquid A is a mixture of hydrochloric acid and hydrobromic acid. The desorption liquid A enters the oxidation device 23, and sodium hypochlorite as an oxidant is added to oxidize the bromide ions in the water to bromine. Then, the bromine is blown out by air and enters the reduction device, that is, the absorption device 24. After the bromine is blown out in the oxidation device 23, the blowout residue liquid can be directly recycled as the regenerant A. If there is oxidant residue in the blowout residue liquid, it can be reduced by adding a reducing agent and then used as the regenerant A. Formic acid is added to the reduction device as a reducing agent to absorb bromine, generating hydrobromic acid and carbon dioxide, and the carbon dioxide is discharged from the absorption device 24. The obtained hydrobromic acid solution enters the distillation device 12 for rectification to obtain hydrobromic acid, distilled water, and formic acid. The generated distilled water is used for the influent water 1 or for preparing the regenerant or directly discharged. The formic acid obtained by distillation in the distillation device 12 is returned to the absorption device 24 as a reducing agent. The obtained hydrobromic acid enters the purification device 13 to adsorb the small amount of bromine generated by distillation and can be used as a product or recycled in production. The purification device 13 selects a bromide-type macroporous strongly basic anion exchange resin (such as D201). Among them, the blowout residue liquid refers to the liquid remaining after the bromine is blown out in the oxidation device.

[0095] After the bromide ion extraction device 3 is regenerated by the regenerant A, the transformation agent B is used to transform the resin into the bicarbonate type. The generated desorption liquid B enters the aerobic section of the sewage treatment plant for treatment and then is discharged.

[0096] For any person skilled in the art, without departing from the scope of the technical solution of the present invention, many possible changes and modifications can be made to the technical solution of the present invention by using the technical content disclosed above, or it can be modified into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A system for extracting hydrobromic acid from bromine-containing wastewater, characterized in that, The bromine-containing wastewater is successively connected to a pretreatment system (2), a bromide ion extraction device (3), and a hydrobromic acid extraction system (5); The pretreatment system (2) includes a filter; The bromide ion extraction device (3) includes an anion exchange resin; the exchange group of the anion exchange resin is an anion with a large content in the treated wastewater and competitive with bromide ions, and is used for selectively adsorbing bromide ions in water; The hydrobromic acid extraction system includes a bromine separation device and a purification device.

2. The system for extracting hydrobromic acid from bromine-containing wastewater according to claim 1, wherein The bromide ion extraction device (3) is also connected to a regenerant extraction system (4); the regenerant extraction system (4) includes an organic matter removal device, a divalent cation removal device, and a concentration device.

3. The system for extracting hydrobromic acid from bromine-containing wastewater according to claim 1, wherein The filter includes sand filtration, precision filtration, bag filtration, ultrafiltration, or microfiltration; the anion exchange resin includes strong-base type, weak-base type, macroporous type, or gel type resin.

4. The system for extracting hydrobromic acid from bromine-containing wastewater according to claim 2, wherein The organic matter removal device includes a nanofiltration device, a microfiltration device, an electro-oxidation device, a biochemical device, or an activated carbon device; the divalent cation removal device includes a nanofiltration device or an ion exchange resin; the concentration device includes an electrodialysis device, a reverse osmosis device, or an evaporation device.

5. The system for extracting hydrobromic acid from bromine-containing wastewater according to claim 2, characterized in that, A crystallization device and a solid-liquid separation device are successively connected after the concentration device; the crystallization device includes a freeze crystallization device or an evaporation crystallization device; the solid-liquid separation device includes a centrifuge or a filter press.

6. The system for extracting hydrobromic acid from bromine-containing wastewater according to claim 1, wherein The bromine separation device includes a combination of a concentration device and a distillation device, a membrane separation device, or a combination of a neutralization device and a separation device; the separation device includes a nanofiltration device or an ion exchange resin; the purification device includes a distillation device or a combination of a distillation device and a purification device or a combination of an evaporation device and a purification device.

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

8. The system for extracting hydrobromic acid from bromine-containing wastewater according to claim 1, wherein, The bromine separation device includes an oxidation device, an absorption device, and a distillation device connected in sequence. The oxidation device oxidizes bromide ions into bromine by adding an oxidant, and then separates them by stripping or distillation; the absorption device absorbs bromine by adding a reducing agent, and after purification by the purification device, bromine or hydrobromic acid is obtained, and then the acid solution obtained after separating bromide ions is used as regenerant A; the oxidant includes chlorine, hydrogen peroxide, hypochlorous acid, sodium hypochlorite, concentrated sulfuric acid; the reducing agent includes sulfur dioxide, formic acid, sodium formate, sodium thiosulfate, sulfurous acid.

9. A treatment method for extracting hydrobromic acid from bromine-containing wastewater, characterized in that, It includes the following steps: 1) The bromine-containing wastewater is passed through the pretreatment system (2) to remove suspended solids in the water; 2) Enter the bromide ion extraction device (3). Under the action of the anion exchange resin, selectively adsorb the bromide ions in the water onto the resin. The bromide-free effluent of the bromide ion extraction device (3) enters the regenerant extraction system (4). In the regenerant extraction system (4), after organic matter removal, divalent cation removal, and concentration, or after organic matter removal, divalent cation removal, concentration, crystallization, and solid-liquid separation, the transformation agent B is obtained; 3) When the bromide ion extraction device (3) is saturated with adsorption, add the regenerant A to the bromide ion extraction device (3) to desorb the bromide ions, forming a desorption solution containing the regenerant A and bromide ions. The desorption solution is separated from the regenerant A and bromide ions through the bromine separation device, and the separated bromide ions enter the purification device for purification; the regenerant A is recycled; 4) After the desorption in step 3) is completed, add the transformation agent B obtained in step 2) to the bromide ion extraction device (3) to convert the exchange group of the anion exchange resin into an anion exchange group that competes with the bromide ions in the wastewater to be treated, for recycling the treatment of bromine-containing wastewater.

10. A treatment method for extracting hydrobromic acid from bromine-containing wastewater according to claim 9, characterized in that, The transformation agent B is an anion salt with a large content in water and having a competitive relationship with bromide ions, including sodium carbonate, sodium bicarbonate, sodium hydroxide, sodium chloride, or sodium sulfate; the regenerant A is a compound that can desorb bromide ions from the resin and can be separated from bromide ions, including sulfuric acid, hydrochloric acid, nitric acid, sodium benzoate, sodium phenolate, or sodium citrate; the desorption solution containing the regenerant A and bromide ions in step S3 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 reduction absorption.

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