A method for desalting a 1,3-propanediol fermentation broth

Abstract

The application discloses a desalination method for 1,3-propanediol fermentation liquor, and comprises the following steps: sequentially performing bacteria removal and concentration on the 1,3-propanediol fermentation liquor to obtain a primary concentrated solution; and performing specific chromatographic separation and desalination on the primary concentrated solution by using a chromatographic separation system to obtain a desalination solution; by the specific chromatographic separation and desalination process, the PDO fermentation liquor can be directly subjected to chromatographic separation and desalination after being filtered by ultrafiltration, the nanofiltration membrane filtration process is reduced, and the PDO extraction process is simplified; in addition, the product yield of PDO in the desalination process of the PDO fermentation liquor can reach more than 98%, the chromatographic separation and desalination rate is increased to more than 90%, the residual amount of the distillation kettle is significantly reduced, the product yield of PDO in the distillation process is increased, and the product quality is significantly improved.

Description

[0001] This invention is a divisional application of Chinese invention patent application filed on December 17, 2021, with application number 2021115501775 and title "A method for desalting and purifying 1,3-propanediol fermentation broth". Technical Field

[0002] This invention relates to the field of bio-based new material preparation technology, specifically to a method for desalting 1,3-propanediol fermentation broth. Background Technology

[0003] 1,3-Propanediol (1,3-PDO) is a colorless, odorless, salty, hygroscopic viscous liquid. It is a raw material for the production of unsaturated polyesters, plasticizers, surfactants, emulsifiers, and demulsifiers. In the polyurethane industry, it is commonly used as a raw material for polyester polyols, an initiator for polyether polyols, and a chain extender for polyurethanes. In the organic chemical industry, it is also an important monomer and intermediate, mainly used as a polymer monomer, such as in the synthesis of polypropylene terephthalate (PTT).

[0004] In the process of producing PDO by microbial fermentation, while the microbial cells produce PDO, they also generate byproducts such as 2,3-butanediol (BDO) and organic acids such as succinic acid, acetic acid, and lactic acid. In addition, after the ammonium ions in the ammonium sulfate used as the nitrogen source for fermentation are consumed, the pH value of the fermentation broth also decreases. In order to maintain the pH value of the fermentation broth at neutral, an alkaline solution, such as a 30% sodium hydroxide solution, needs to be added to the fermentation broth. Therefore, after fermentation, the fermentation broth will contain a large amount of salt, with a salt content of about 3%. If these salts are not removed, subsequent processes such as distillation will be difficult to carry out, thus hindering the extraction of 1,3-propanediol.

[0005] Currently, there are various methods for desalting PDO fermentation broth, such as ion exchange, nanofiltration, electrodialysis, and alcohol precipitation. However, these methods still suffer from problems such as low separation efficiency, unsuitability for industrial application, significant environmental pollution, and high cost. With improvements in the performance of heterogeneous membranes, they are gradually replacing expensive homogeneous membranes, significantly reducing investment in electrodialysis equipment and promoting the industrial application of electrodialysis in the desalination of 1,3-propanediol fermentation broth. However, on the one hand, PDO fermentation broth produced by fermentation typically undergoes ultrafiltration for sterilization and nanofiltration for protein removal before being subjected to further treatment. Electrodialysis is used for desalination. Electrodialysis utilizes the migration of anions and cations in the PDO fermentation broth under the influence of an electric field, allowing them to pass through anion exchange membranes and cation exchange membranes, respectively. This process removes the anions and cations from the PDO fermentation broth. The salts in the PDO fermentation broth are mainly organic acid salts sodium succinate and sodium acetate. These two salts cannot completely dissociate in aqueous solution, especially in the later stages of electrodialysis desalination when the organic salt concentration is extremely low. This severe dissociation leads to a decrease in the current efficiency of the fermentation broth and a drop in its pH value. Furthermore, during electrodialysis desalination... During the process, residual proteins in the fermentation broth can contaminate the ion exchange membrane, leading to a decrease in electrodialysis desalination efficiency. Furthermore, during electrodialysis desalination of PDO fermentation broth, not only do anions and cations permeate through the ion exchange membrane, but PDO and BDO products also diffuse from the dilute chamber into the concentrate chamber due to concentration gradient, resulting in product loss. According to the company's current production data, the loss rate of PDO and BDO products during PDO fermentation broth desalination is approximately 5%. This means that for a PDO plant with an annual production capacity of 20,000 tons, the annual loss of PDO during electrodialysis desalination reaches 1,000 tons. Based on the current price of 30,000 yuan / ton, this portion of PDO is worth as much as 30 million yuan. Furthermore, the desalination rate of electrodialysis is not ideal. After subsequent concentration of the desalinated liquid, the salt concentration is increased. During the subsequent purification process, the residual salt in the material will also affect the product yield of the distillation process, resulting in a large amount of distillation kettle residue. The residual PDO product in the distillation kettle residue needs to be further recovered using a scraped evaporation process, making the process quite complex. Although electrodialysis desalination can be repeated multiple times to improve the desalination rate without considering energy consumption, it is obviously not conducive to industrial application. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide an improved desalting method for 1,3-propanediol fermentation broth, which can achieve a high desalting rate, a high PDO product yield, a low residue, and fewer process steps.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a method for desalting 1,3-propanediol fermentation broth, the desalting method comprising:

[0008] The 1,3-propanediol fermentation broth was sequentially filtered to remove bacteria and concentrated to obtain a primary concentrate.

[0009] The obtained primary concentrate is subjected to chromatographic separation and desalting using a chromatographic separation system. The chromatographic separation system includes n sequentially circulated chromatographic separation columns, where n is an integer greater than or equal to 3. The resin used in the chromatographic separation columns is sodium-type uniform granular gel cation exchange chromatographic resin.

[0010] The chromatographic separation and desalting includes m consecutive repeating cycles, where m and n are the same; wherein, in each repeating cycle, the following steps are performed sequentially:

[0011] Feed circulation: A portion of the primary concentrate is circulated into the chromatographic separation system until one chromatographic column is enriched for component A and another chromatographic column is enriched for component B. Component A contains 1,3-propanediol and component B contains salts.

[0012] First discharge: Eluent is introduced into the inlet of the chromatographic separation column for enriched component A to push component A out of the chromatographic separation column for enriched component A and collect it;

[0013] A portion of the concentrate is introduced into the inlet of the chromatographic column preceding the column for enriching component B, thereby expelling component B from the column for enriching component B and collecting it; the preceding column is the one preceding the column for enriching component B in the opposite direction of the circulation flow.

[0014] Second discharge: Eluent is introduced again through the inlet of the first discharge to push out the remaining component B in the chromatographic separation column enriched in the first discharge, and collected;

[0015] In two adjacent repetition cycles, the latter repetition cycle has the following changes relative to the former repetition cycle:

[0016] During the first discharge, the chromatographic separation columns collecting components A and B both switched to the next column along the direction of circulation.

[0017] During the second discharge, the chromatographic separation columns collecting the remaining component B were switched to the next one along the direction of circulation;

[0018] After completing m repetition cycles, the collected components A are mixed to obtain the desalination solution.

[0019] In some embodiments, the 1,3-propanediol fermentation broth is produced from renewable biomass by fermentation of bacteria such as Klebsiella pneumoniae, Clostridium, Lemonobacterium, Lactobacillus, Corynebacterium glutamicum, or Escherichia coli, or by fermentation of genetically engineered bacteria of these genera.

[0020] The filtration and sterilization process employs ultrafiltration, which uses a ceramic membrane for sterilization and protein removal. The filtration pore size of the ceramic membrane is 5nm-50nm.

[0021] The water content of the concentrate is controlled between 50wt% and 70wt%.

[0022] In some embodiments, the chromatographic separation and desalting operation pressure is 0.1-1.0 MPa and the operating temperature is 20-60°C; further, the chromatographic separation and desalting operation pressure is 0.2-0.5 MPa and the operating temperature is 25-55°C; even further, the chromatographic separation and desalting operation pressure is 0.2-0.4 MPa and the operating temperature is 30-50°C.

[0023] In some implementations, n is an integer greater than or equal to 6.

[0024] In some embodiments, when n is 6, the chromatographic separation system includes a first chromatographic separation column, a second chromatographic separation column, a third chromatographic separation column, a fourth chromatographic separation column, a fifth chromatographic separation column, and a sixth chromatographic separation column that are connected in sequence to form a loop. At least one valve for communication is provided between adjacent chromatographic separation columns. The valve is used to control the feed or the eluent and to discharge specific components.

[0025] The feed cycle time is 6-20 min, and the chromatographic separation column for enriched component A is separated from the chromatographic separation column for enriched component B by 3 chromatographic separation columns.

[0026] In some embodiments, the circulation rate in the feed circulation process is 1-6 BV / h, and the feed volume of the primary concentrate is 0.05-0.3 BV; further, the circulation rate in the feed circulation process is 2-4 BV / h, and the feed volume of the primary concentrate is 0.08-0.22 BV.

[0027] In some embodiments, during the first discharge step, the feed volume of the eluent used to discharge component A is 0.1-0.42 BV, and the feed volume of the primary concentrate used to discharge component B is 0.05-0.3 BV. The discharge of components A and B is performed simultaneously. Furthermore, during the discharge of component A, the outlet of the next chromatographic column in the circulation direction of the column enriching component A is closed; during the discharge of component B, the outlet of the next chromatographic column in the circulation direction of the column enriching component B is closed. Further, during the first discharge step, the feed volume of the eluent used to discharge component A is 0.08-0.24 BV, and the feed volume of the primary concentrate used to discharge component B is 0.08-0.22 BV.

[0028] In some embodiments, during the second discharge step, the feed volume of the eluent used to eject the remaining component B is 0.06-0.3 BV. During the ejection of the remaining component B, the outlet of the next chromatographic column in the circulation flow direction of the chromatographic column enriched with component B in the first discharge is closed. Further, during the second discharge step, the feed volume of the eluent used to eject the remaining component B is 0.08-0.22 BV.

[0029] In some embodiments, the eluent is water.

[0030] In some embodiments, the desalination method further includes the steps of concentrating the desalted solution to obtain a secondary concentrate and purifying the secondary concentrate. The concentration is carried out by multi-effect evaporation, MVR evaporation, or multi-effect distillation, and the water content of the secondary concentrate is 5wt%-45wt%. The purification is carried out by distillation, and the process parameters for distillation are: operating pressure of 5-30 mmHg and distillation column bottom temperature of 80-160℃.

[0031] Another technical solution provided by the present invention: a method for desalting and purifying 1,3-propanediol fermentation broth, comprising the following steps: 1,3-propanediol is produced by microbial fermentation to obtain 1,3-propanediol fermentation broth.

[0032] (1) The 1,3-propanediol fermentation broth was filtered and sterilized and concentrated in sequence to obtain a primary concentrate.

[0033] (2) The concentrated solution obtained in step (1) is subjected to chromatographic separation and desalting using a chromatographic separation system, wherein the chromatographic separation system comprises n chromatographic separation columns that are connected in a sequential cycle, where n is an integer greater than or equal to 3;

[0034] The chromatographic separation and desalting includes m consecutive repeating cycles, where m and n are the same; wherein, in each repeating cycle, the following steps are performed sequentially:

[0035] Feed circulation: A portion of the primary concentrate is circulated into the chromatographic separation system until one chromatographic column is enriched for component A and another chromatographic column is enriched for component B. Component A contains 1,3-propanediol and component B contains salts.

[0036] First discharge: Eluent is introduced into the inlet of the chromatographic separation column for enriched component A to push component A out of the chromatographic separation column for enriched component A and collect it;

[0037] A portion of the concentrate is introduced into the inlet of the chromatographic column preceding the column for enriching component B, thereby expelling component B from the column for enriching component B and collecting it; the preceding column is the one preceding the column for enriching component B in the opposite direction of the circulation flow.

[0038] Second discharge: Eluent is introduced again through the inlet of the first discharge to push out the remaining component B in the chromatographic separation column enriched in the first discharge, and collected;

[0039] In two adjacent repetition cycles, the latter repetition cycle has the following changes relative to the former repetition cycle:

[0040] During the first discharge, the chromatographic separation columns collecting components A and B both switched to the next column along the direction of circulation.

[0041] During the second discharge, the chromatographic separation columns collecting the remaining component B were switched to the next one along the direction of circulation;

[0042] After completing m repetition cycles, the collected components A from multiple cycles are mixed to obtain a desalination solution;

[0043] (3) The desalted solution obtained in step (2) is concentrated to obtain a secondary concentrate, and then the secondary concentrate is purified to obtain 1,3-propanediol.

[0044] In this invention, the resin in the chromatographic separation column remains in the chromatographic separation column, and the primary concentrate and eluent introduced move relative to the resin.

[0045] According to some preferred aspects of the invention, in step (2), n is an integer greater than or equal to 6.

[0046] According to some preferred aspects of the present invention, in step (2), the resin used in the chromatographic separation column is a sodium-type uniform granular gel cation exchange resin, which can more easily separate component A and component B in the chromatographic column compared to other resins.

[0047] According to some preferred aspects of the invention, in step (2), the circulation rate during the feed circulation process is 1-6 BV / h. More preferably, it is 2-4 BV / h.

[0048] In this invention, "BV" refers to the volume of a separation column.

[0049] According to some preferred aspects of the present invention, in step (2), the feed volume of the primary concentrate introduced in the feed circulation process is 0.05-0.3 BV, more preferably 0.08-0.22 BV;

[0050] In the first discharge process, the feed volume of the eluent used to discharge component A is 0.1-0.42 BV, more preferably 0.08-0.24 BV; the feed volume of the primary concentrate used to discharge component B is 0.05-0.3 BV, more preferably 0.08-0.22 BV.

[0051] In the second discharge process, the feed volume of the eluent used to push out the remaining component B is 0.06-0.3 BV, more preferably 0.08-0.22 BV.

[0052] According to some preferred aspects of the present invention, in step (2), during the first discharge process, the operation of discharging component A and component B is performed simultaneously; and during the discharging of component A, the outlet of the next chromatographic column of the enriched component A along the circulation flow direction is closed; during the discharging of component B, the outlet of the next chromatographic column of the enriched component B along the circulation flow direction is closed.

[0053] In the second discharge process, during the discharge of the remaining component B, the outlet of the next chromatographic column along the circulation flow direction of the chromatographic column where component B was enriched in the first discharge is closed.

[0054] According to some preferred aspects of the present invention, in step (2), when n is 6, the cycle time of the feed cycle is 6-20 min, and the chromatographic separation column for enriching component A is spaced 3 chromatographic separation columns apart from the chromatographic separation column for enriching component B.

[0055] According to some preferred aspects of the present invention, in step (2), the operating pressure of the chromatographic separation and desalting is 0.1-1.0 MPa, and the operating temperature is 20-60°C. Further, in step (2), the operating pressure of the chromatographic separation and desalting is 0.2-0.5 MPa, and the operating temperature is 25-55°C. Even further, in step (2), the operating pressure of the chromatographic separation and desalting is 0.2-0.4 MPa, and the operating temperature is 30-50°C.

[0056] According to some preferred aspects of the present invention, in step (2), the eluent is water.

[0057] According to some specific aspects of the present invention, component A also includes byproducts such as 2,3-butanediol (BDO) and glycerol, and the three substances migrate at approximately the same rate in the chromatographic column.

[0058] According to some specific aspects of the present invention, the salts of component B include acetate, succinate, and also contain proteins and pigments. The three substances migrate at approximately the same speed in the chromatographic column, and at different speeds than component A.

[0059] According to some preferred aspects of the present invention, in step (1), the filtration and sterilization are performed using ultrafiltration. According to one specific aspect of the present invention, the ultrafiltration is performed using a ceramic membrane for sterilization and protein removal, the ceramic membrane having a pore size of 5 nm-50 nm.

[0060] According to some preferred aspects of the present invention, in step (1), the concentration is carried out using multi-effect evaporation concentration, MVR evaporation concentration, or multi-effect distillation, and the water content of the primary concentrate is 50-70 wt%. Controlling the water content of the primary concentrate within this range can significantly reduce the amount of eluent added, reduce the cost of subsequent evaporation and dehydration, and improve the economy of the entire process. According to a specific aspect of the present invention, in step (1), the concentration is carried out using multi-effect evaporation concentration, where multi-effect evaporation concentration refers to using the steam of the previous effect as the heat source of the subsequent effect, including triple-effect evaporation, quadruple-effect evaporation, quintuple-effect evaporation, and six-effect evaporation, etc.

[0061] In some embodiments of the present invention, the 1,3-propanediol fermentation broth is produced by fermentation of bacteria of the genera *Klebsiella*, *Clostridium*, *Citrobacter*, *Lactobacillus*, *Corynebacterium glutamicum*, or *Escherichia coli*, or by fermentation of genetically engineered bacteria of these genera.

[0062] According to one specific aspect of the present invention, the renewable biomass is a conventional renewable biological raw material in the art, specifically glycerol, etc.; the method of producing 1,3-propanediol by fermentation with Klebsiella pneumoniae using renewable biomass as raw material is a conventional method in the art. Preferably, the specific implementation of the present invention is as follows: after inoculation of the fermenter, the fermentation broth temperature is controlled at 30-40℃, the pH value at 6-7, the aeration rate at 0.01-0.5 vvm, and the stirring rate at 20-100 rpm. During fermentation, the concentration of the substrate glycerol in the fermentation broth is measured, and glycerol is added according to the glycerol consumption rate to ensure that the glycerol concentration in the fermentation broth is 0.5-30 g / L. After fermentation for 30-60 hours, the product is removed from the fermentation tank.

[0063] According to some preferred aspects of the present invention, in step (3), the concentration is carried out by multi-effect evaporation concentration, MVR evaporation concentration or multi-effect distillation, and the water content of the secondary concentrate is 5-45 wt%.

[0064] According to some preferred aspects of the present invention, in step (3), the purification is carried out by distillation purification, and the process parameters of the distillation purification are: operating pressure of 5-30 mmHg and distillation column temperature of 80-160℃.

[0065] In some embodiments of the present invention, the distillation and purification process is as follows: Initially, light components such as water and a small amount of BDO are distilled under relatively low reboiler temperature (approximately 80°C) and relatively high operating pressure (approximately 30 mmHg). Once the water distillation is largely complete, the reboiler temperature gradually rises, and continuous feeding begins, maintaining the reboiler temperature at 110-120°C and the operating pressure at 10-20 mmHg. After the material feeding is complete, the operating pressure is further reduced, and the reboiler temperature continues to rise until the viscosity of the material in the reboiler reaches the required value of 140-160 cp (100°C), at which point the distillation ends. The minimum operating pressure is approximately 5 mmHg, and the maximum temperature can reach 160°C.

[0066] Furthermore, when higher purity PDO and BDO products are required, separation operations, including rectification, can be performed on the 1,3-propanediol product after distillation and purification.

[0067] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0068] This invention addresses the problems existing in the preparation of 1,3-propanediol and innovatively proposes an improved method for preparing 1,3-propanediol. This method employs a specific chromatographic separation and desalting process, which not only allows for direct chromatographic separation and desalting of PDO fermentation broth after ultrafiltration in the early stage, reducing the nanofiltration membrane filtration step and simplifying the PDO extraction process, but also achieves a PDO product yield of over 98% during the desalting process, increases the chromatographic separation and desalting rate to over 90%, significantly reduces distillation residue, improves the PDO product yield in the distillation process, and significantly enhances product quality. Attached Figure Description

[0069] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0070] Figure 1 This is a flowchart of the desalting and purification method for 1,3-propanediol fermentation broth used in the embodiments of the present invention;

[0071] Figure 2 This is a schematic diagram of the chromatographic separation system used in an embodiment of the present invention;

[0072] Figure 3 This is a schematic diagram of the feed circulation process for one repeating cycle in the chromatographic separation and desalting process of this invention embodiment;

[0073] Figure 4This is a schematic diagram of the component concentration distribution in each chromatographic column when the feed cycle reaches the point where the next process can proceed, i.e., the first discharge, in an embodiment of the present invention.

[0074] Figure 5 for Figure 3 A schematic diagram of the next process after the one shown, namely the first discharge process;

[0075] Figure 6 This is a schematic diagram of the component concentration distribution in each chromatographic separation column at the end of the first discharge in an embodiment of the present invention;

[0076] Figure 7 for Figure 5 A schematic diagram of the next process after the one shown, namely the second discharge process;

[0077] Figure 8 This is a schematic diagram of the component concentration distribution in each chromatographic separation column at the end of the second discharge in an embodiment of the present invention;

[0078] The components include: 1. Fermentation tank; 2. 1,3-propanediol fermentation broth; 3. Ultrafiltration device; 4. Ultrafiltration filtrate; 5. Primary evaporation and dehydration device; 6. Primary steam condensate; 7. Primary concentrate; 8. Chromatographic separation system; 9. Eluent; 10. Residual liquid phase; 11. Desalting solution; 12. Secondary evaporation and dehydration device; 13. Secondary steam condensate; 14. Secondary concentrate; 15. Distillation device; 16. Distillate; 17. Distillation kettle residue.

[0079] 18. Valve; 191. First chromatographic column; 192. Second chromatographic column; 193. Third chromatographic column; 194. Fourth chromatographic column; 195. Fifth chromatographic column; 196. Sixth chromatographic column; In the schematic diagram of the valve, a circle indicates that the valve is in the open state, and a circle with a diagonal line above it indicates that the valve is in the closed state. Detailed Implementation

[0080] Currently, in the process of preparing 1,3-propanediol using microbial fermentation, electrodialysis is commonly used for desalination. With the improvement of heterogeneous membrane performance, the cost of this technology has been greatly reduced, and it has been well applied in the desalination process of 1,3-propanediol preparation. However, in practice, this electrodialysis desalination process still has problems such as membrane fouling leading to a decrease in equipment processing capacity, large loss of PDO products, and less than ideal desalination rate. Although the desalination rate can be improved by repeated electrodialysis desalination, the cost is too high, which is not conducive to industrial application.

[0081] Based on the above problems, the inventors of this invention innovatively proposed using chromatographic separation for the desalting of PDO fermentation broth. Separation can be achieved based on the differences in the migration speed of different substances in the chromatographic resin column. However, conventional chromatographic separation methods cannot maximize the removal of salts from the PDO fermentation broth, and also suffer from significant PDO product loss. Through long-term practical research, the inventors proposed a chromatographic separation system comprising n sequentially interconnected chromatographic separation columns. Furthermore, they proposed setting multiple consecutive repetition cycles for the chromatographic separation desalting process according to the number of chromatographic separation columns. For each repetition cycle, the following steps were designed sequentially: feed circulation, first discharge, and second discharge. In the feed circulation, a portion of the primary concentrate is circulated into the chromatographic separation system until one chromatographic separation column is enriched for component A, and another column is enriched for component B. Component A contains 1,3-propanediol, and component B contains salts. In the first discharge, eluent is introduced through the inlet of the column containing enriched component A, pushing component A out of the column and collecting it. A portion of the first concentrate is introduced through the inlet of the column preceding the column containing enriched component B, pushing component B out of the column containing enriched component B and collecting it. This preceding column is the one preceding the column containing enriched component B in the opposite direction of the circulation flow. In the second discharge, eluent is introduced again through the inlet of the column containing the first discharge, pushing out the remaining component B from the column containing enriched component B in the first discharge and collecting it.

[0082] Simultaneously, in two adjacent repeat cycles, the latter repeat cycle has the following changes relative to the former repeat cycle: In the first discharge, the chromatographic separation columns for collecting components A and B are switched to the next one along the circulation flow direction; In the second discharge, the chromatographic separation columns for collecting the remaining component B are switched to the next one along the circulation flow direction; After completing m repeat cycles, the components A collected multiple times are mixed to obtain a desalting solution.

[0083] The desalination rate of the desalting solution obtained by the above chromatographic separation process can reach over 93%, and the yield of PDO in the chromatographic separation and desalting process can reach 99%.

[0084] Furthermore, by employing the chromatographic separation and desalting method described above in this invention, the PDO fermentation broth can also be directly separated and desalted by chromatography after ultrafiltration, reducing the nanofiltration membrane filtration step, simplifying the PDO extraction process, and achieving the desired ideal results.

[0085] Furthermore, by employing the chromatographic separation and desalting method described above in this invention, compared to conventional chromatographic separation methods, the method yields a higher concentration of desalted solution and requires less eluent.

[0086] Furthermore, such as Figure 1 As shown, the process flow diagram of the 1,3-propanediol fermentation broth desalting and purification method in the embodiment of the present invention is given. In the fermenter 1, renewable biomass is used as raw material and Klebsiella pneumoniae is used to ferment and produce 1,3-propanediol to obtain 1,3-propanediol fermentation broth 2. Then, ultrafiltration is performed by ultrafiltration device 3 to obtain ultrafiltration filtrate 4. Then, it is dehydrated and concentrated by primary evaporation and dehydration device 5 to obtain primary concentrate 7. Other components such as primary steam condensate 6 are discharged. Then, chromatographic separation system 8 is used for chromatographic separation and desalting. Eluent 9 is used to elute component B. After chromatographic separation and desalting, residual liquid phase 10 and desalted liquid 11 are obtained. Then, secondary evaporation and dehydration device 12 is used to evaporate, concentrate and dehydrate desalted liquid 11 to obtain secondary concentrate 14 and secondary steam condensate 13. Secondary steam condensate 13 is discharged. Then, secondary concentrate 14 is purified by distillation device 15 to obtain distillate 16 and distillation kettle residue 17. Distillate 16 can be further purified in other downstream processes (e.g., rectification process).

[0087] Furthermore, such as Figure 2 As shown, a schematic diagram of the chromatographic separation system used in the embodiment of the present invention is provided, including a first chromatographic separation column 191, a second chromatographic separation column 192, a third chromatographic separation column 193, a fourth chromatographic separation column 194, a fifth chromatographic separation column 195, and a sixth chromatographic separation column 196 connected in sequence to form a circulation loop. At least one valve 18 is provided between adjacent chromatographic separation columns for communication. The valve 18 can be used to control the feed or the eluent, and can also discharge specific components.

[0088] Furthermore, such as Figure 3-8 As shown, it provides a schematic diagram of one repeating cycle in the chromatographic separation and desalting process in an embodiment of the present invention;

[0089] Specifically: such as Figure 3 As shown, during chromatographic separation and desalting, feed is introduced through any of the valves. For example, the valve between the third and fourth chromatographic columns can be selected to feed the fourth column. After a period of circulation, when one column is enriched for component A and another column is enriched for component B, the circulation is stopped, and the first discharge step can proceed. At this point, the concentrations of components A and B in each column are shown in the diagram below. Figure 4As shown, it can be seen that at this time, the first chromatographic separation column enriching component A has a high concentration and high purity of component A, and almost no component B. Similarly, the fifth chromatographic separation column enriching component B has a high concentration and high purity of component B, and almost no component A. This state can be obtained by multiple sampling analyses, preferably by online detection by liquid chromatography, and the time point of this state can be used as a standard in the subsequent repeated production process (e.g., by programming, directly controlled by the program).

[0090] When performing the first unloading process, such as Figure 5 As shown, by introducing eluent through the valve at the inlet of the first chromatographic column and closing the valve between the second and third chromatographic columns, component A enriched in the first chromatographic column is expelled, and high-purity component A is collected. Simultaneously, by directly feeding a portion of the concentrated solution (as a replenishment of the chromatographic separation system) through the inlet of the fourth chromatographic column and closing the valve at the outlet of the sixth chromatographic column, component B enriched in the fifth chromatographic column is expelled, and high-purity component B is collected. After this process is completed, the concentration distribution of components in each chromatographic column is shown in the diagram below. Figure 6 As shown, at this point, component A in the first chromatographic separation column has been basically discharged, with only a small amount remaining, while there is still a large amount of component B in the fifth chromatographic separation column. Therefore, the next step of the process, the second discharge, is required.

[0091] When performing the second unloading process, such as Figure 7 As shown, by introducing eluent into the inlet of the first chromatographic column and closing the valve at the outlet of the sixth chromatographic column, the first, second, third, fourth, and fifth chromatographic columns are sequentially connected. This pushes out most of the remaining component B in the fifth chromatographic column, continuing to obtain high-purity component B. After this process is completed, the component concentration distribution in each chromatographic column is shown in the diagram below. Figure 8 As shown, at this point, component A in the first chromatographic column is present in very small amounts and component B is almost non-existent; component B in the fifth chromatographic column is present in very small amounts and component A is almost non-existent; while the second chromatographic column is relatively rich in component A and contains very small amounts of component B compared to the other chromatographic columns; the contents of component A and component B in the third chromatographic column are basically equal; the fourth chromatographic column is relatively rich in component B and contains a small amount of component A compared to the other chromatographic columns; and the sixth chromatographic column contains very small amounts of both component A and component B.

[0092] After the above steps, the first repeat cycle ends. Based on the component concentration distribution in each chromatographic column after the above steps, this invention further proposes that in the second repeat cycle, the feed position of the feed circulation process remains unchanged, but with the following changes: In the first discharge of the second repeat cycle, the chromatographic columns collecting components A and B switch to the next column along the circulation flow direction; in the second discharge of the second repeat cycle, the chromatographic columns collecting the remaining component B switch to the next column along the circulation flow direction; with this setting, the chromatographic column enriching component A can switch to the next column along the circulation flow direction (which is the second chromatographic column in the second repeat cycle), and the chromatographic column enriching component B can switch to the next column along the circulation flow direction (which is the sixth chromatographic column in the second repeat cycle).

[0093] When performing a number of repetition cycles corresponding to the number of chromatographic separation columns, each chromatographic separation column undergoes a discharge process, and each discharge occurs on a chromatographic separation column enriched for component A or component B. This maximizes the separation and collection of components A and B in the system. After completing m repetition cycles, the components A collected multiple times are mixed to obtain a desalting solution. Practice has shown that the desalting rate in this desalting solution can reach over 93%, and the yield of PDO in the chromatographic separation and desalting process can reach over 99%.

[0094] The above-described solutions are further illustrated below with reference to specific embodiments. It should be understood that these embodiments are intended to illustrate the basic principles, main features, and advantages of the present invention, and the present invention is not limited to the scope of these embodiments. The implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are generally those used in conventional experiments. Unless otherwise stated, all raw materials are commercially available or prepared according to conventional methods in the art. In the above embodiments and comparative examples, the experimental data in the tables were obtained by liquid chromatography or gas chromatography, respectively.

[0095] Example 1

[0096] This example provides a method for desalting and purifying 1,3-propanediol fermentation broth, the method comprising the following steps:

[0097] (i) Using renewable biomass (specifically glycerol) as raw material, 1,3-propanediol is produced by fermentation with Klebsiella pneumoniae to obtain 1,3-propanediol fermentation broth; the specific implementation method is as follows:

[0098] After inoculation in the fermenter, the fermentation broth temperature was controlled at 37℃, pH value at 6.5, aeration rate at 0.06 vvm, and stirring rate at 45 rpm. During fermentation, the concentration of substrate glycerol in the fermentation broth was measured, and glycerol was added according to the glycerol consumption rate to ensure that the glycerol concentration in the fermentation broth was 0.3-25 g / L. The fermentation was completed after 44 hours.

[0099] (ii) The 1,3-propanediol fermentation broth obtained in step (i) is filtered and sterilized and concentrated in sequence to obtain a primary concentrate;

[0100] Ultrafiltration is used for filtration and sterilization, and ultrafiltration is carried out using a ceramic membrane (the filtration pore size of the ceramic membrane is 5nm).

[0101] Concentration is carried out using a multi-effect evaporator. The process parameters of the multi-effect evaporator are as follows: the vacuum gauge pressures of the first / second / third / fourth effect evaporators are -0.065 MPa / -0.07 MPa / -0.085 MPa / -0.095 MPa, respectively.

[0102] (iii) The concentrate obtained in step (ii) is processed using... Figure 2 The chromatographic separation system shown performs chromatographic separation and desalting. The system comprises six sequentially connected chromatographic columns, and the chromatographic separation and desalting consists of six consecutive repeat cycles. The specific operation procedure for the first repeat cycle is as follows: Figure 3-8 The process is as shown, and subsequent repeat cycles are performed as follows: In two adjacent repeat cycles, the latter repeat cycle is controlled to have the following changes relative to the former repeat cycle: In the first discharge, the chromatographic separation columns for collecting components A and B are switched to the next one along the circulation flow direction; In the second discharge, the chromatographic separation columns for collecting the remaining component B are switched to the next one along the circulation flow direction; After completing 6 repeat cycles, the components A collected multiple times are mixed to obtain the desalting solution;

[0103] The chromatographic separation column uses sodium-type uniform-particle gel cation chromatography resin (LX-1850 uniform-particle gel cation chromatography resin (280-320μm), Xi'an Lanxiao Technology New Material Co., Ltd.);

[0104] In the feeding circulation process, the circulation flow rate is 2.2 BV / h, and the circulation time is 8 min;

[0105] In the feed circulation process, the feed volume of the primary concentrate is 0.1 BV;

[0106] In the first discharge process, the feed volume of the eluent used to discharge component A is 0.16 BV, and the feed volume of the primary concentrate used to discharge component B is 0.1 BV.

[0107] In the second discharge process, the feed volume of the eluent used to push out the remaining component B is 0.08 BV;

[0108] The eluent is water;

[0109] The chromatographic separation operation pressure is 0.35 MPa, and the operating temperature is 30℃.

[0110] (iv) The desalination solution obtained in step (iii) is concentrated to obtain a secondary concentrate, and then the secondary concentrate is purified to obtain 1,3-propanediol. The concentration is carried out using a multi-effect evaporator, and the process parameters of the multi-effect evaporator are: the vacuum gauge pressure of the first / second / third / fourth effect evaporators are -0.065 MPa / -0.07 MPa / -0.085 MPa / -0.095 MPa, respectively.

[0111] The purification process employs distillation. The distillation process involves: initially distilling light components such as water and a small amount of BDO under relatively low reboiler temperature (approximately 80°C) and relatively high operating pressure (approximately 30 mmHg). Once the water distillation is largely complete, the reboiler temperature gradually rises, and continuous feeding begins, maintaining the reboiler temperature at 115±5°C and the operating pressure at 15±5 mmHg. After the material feeding is complete, the operating pressure is further reduced, and the reboiler temperature continues to rise until the viscosity of the material in the reboiler reaches the process requirement of 150±5 cp (100°C), at which point distillation ends. The minimum operating pressure is approximately 5 mmHg, and the maximum temperature can reach 160°C.

[0112] The experimental data are shown in Table 1.

[0113] Table 1. Statistical analysis of chromatographic separation and desalting data of fermentation broth.

[0114]

[0115] Table 1 shows that the ratio of eluent to primary concentrate in the chromatographic separation and desalting process is 2.4:1, and the PDO yield reaches 97.5% (yield = (mass of desalting solution × PDO content in desalting solution) / (mass of primary concentrate × PDO content in primary concentrate) × 100%). The total salt removal rate, i.e., the desalting rate, reaches 91.47% (desalting rate = (1 - mass of desalting solution × salt content in desalting solution) / (mass of primary concentrate × salt content in primary concentrate) × 100%). Both the product yield and salt removal rate are significantly higher than those of the electrodialysis desalting process. After secondary concentration of the desalting solution, distillation is performed. The residue in the distillation vessel accounts for 13.69% of the PDO yield (mass of distillate × PDO content in distillate), which is significantly reduced compared to the electrodialysis desalting process. The PDO yield during distillation increases to 98%.

[0116] Example 2

[0117] This example provides a method for desalting and purifying 1,3-propanediol fermentation broth, the method comprising the following steps:

[0118] (i) Using renewable biomass (specifically glycerol) as raw material, 1,3-propanediol is produced by fermentation with Klebsiella pneumoniae to obtain 1,3-propanediol fermentation broth; the specific implementation method is as follows:

[0119] After inoculation in the fermenter, the fermentation broth temperature was controlled at 37℃, pH value at 6.5, aeration rate at 0.06 vvm, and stirring rate at 45 rpm. During fermentation, the concentration of substrate glycerol in the fermentation broth was measured, and glycerol was added according to the glycerol consumption rate to ensure that the glycerol concentration in the fermentation broth was 0.3-25 g / L. The fermentation was completed after 44 hours.

[0120] (ii) The 1,3-propanediol fermentation broth obtained in step (i) is filtered and sterilized and concentrated in sequence to obtain a primary concentrate;

[0121] Ultrafiltration is used for filtration and sterilization, and ultrafiltration is carried out using a ceramic membrane (the filtration pore size of the ceramic membrane is 5nm).

[0122] Concentration is carried out using a multi-effect evaporator. The process parameters of the multi-effect evaporator are as follows: the vacuum gauge pressures of the first / second / third / fourth effect evaporators are -0.068 MPa / -0.072 MPa / -0.086 MPa / -0.096 MPa, respectively.

[0123] (iii) The concentrate obtained in step (ii) is processed using... Figure 2 The chromatographic separation system shown performs chromatographic separation and desalting. The system comprises six sequentially connected chromatographic columns, and the chromatographic separation and desalting consists of six consecutive repeat cycles. The specific operation procedure for the first repeat cycle is as follows: Figure 3-8 The process is as shown, and subsequent repeat cycles are performed as follows: In two adjacent repeat cycles, the latter repeat cycle is controlled to have the following changes relative to the former repeat cycle: In the first discharge, the chromatographic separation columns for collecting components A and B are switched to the next one along the circulation flow direction; In the second discharge, the chromatographic separation columns for collecting the remaining component B are switched to the next one along the circulation flow direction; After completing 6 repeat cycles, the components A collected multiple times are mixed to obtain the desalting solution;

[0124] The chromatographic separation column uses sodium-type uniform granular gel cation exchange resin.

[0125] In the feeding circulation process, the circulation flow rate is 2.2 BV / h, and the circulation time is 8 min;

[0126] In the feed circulation process, the feed volume of the primary concentrate is 0.1 BV;

[0127] In the first discharge process, the feed volume of the eluent used to discharge component A is 0.16 BV, and the feed volume of the primary concentrate used to discharge component B is 0.1 BV.

[0128] In the second discharge process, the feed volume of the eluent used to push out the remaining component B is 0.14 BV;

[0129] The eluent is water;

[0130] The chromatographic separation operation pressure is 0.25 MPa, and the operating temperature is 50℃.

[0131] (iv) The desalination solution obtained in step (iii) is concentrated to obtain a secondary concentrate, and then the secondary concentrate is purified to obtain 1,3-propanediol. The concentration is carried out using a multi-effect evaporator, and the process parameters of the multi-effect evaporator are: the vacuum gauge pressure of the first / second / third / fourth effect evaporators are -0.065 MPa / -0.07 MPa / -0.085 MPa / -0.095 MPa, respectively.

[0132] The purification process employs distillation. The distillation process involves: initially distilling light components such as water and a small amount of BDO under relatively low reboiler temperature (approximately 80°C) and relatively high operating pressure (approximately 30 mmHg). Once the water distillation is largely complete, the reboiler temperature gradually rises, and continuous feeding begins, maintaining the reboiler temperature at 115±5°C and the operating pressure at 15±5 mmHg. After the material feeding is complete, the operating pressure is further reduced, and the reboiler temperature continues to rise until the viscosity of the material in the reboiler reaches the process requirement of 150±5 cp (100°C), at which point distillation ends. The minimum operating pressure is approximately 5 mmHg, and the maximum temperature can reach 160°C.

[0133] The experimental data are shown in Table 2.

[0134] Table 2. Statistical analysis of chromatographic separation and desalting data of fermentation broth.

[0135]

[0136]

[0137] Table 2 shows that in the chromatographic separation and desalting process, the ratio of eluent to primary concentrate was 3:1, achieving a PDO yield of 98.8% and a total salt removal rate of 92.34%. Both the product yield and salt removal rate were significantly higher than those of the electrodialysis desalting process. After secondary concentration of the desalting solution, distillation was performed. The residue in the distillation vessel accounted for only 12.62% of the PDO yield, a significant reduction compared to the electrodialysis desalting process. The PDO yield during distillation increased to 98%.

[0138] Example 3

[0139] This example provides a method for desalting and purifying 1,3-propanediol fermentation broth, the method comprising the following steps:

[0140] (i) Using renewable biomass (specifically glycerol) as raw material, 1,3-propanediol is produced by fermentation with Klebsiella pneumoniae to obtain 1,3-propanediol fermentation broth; the specific implementation method is as follows:

[0141] After inoculation in the fermenter, the fermentation broth temperature was controlled at 37℃, pH value at 6.5, aeration rate at 0.06 vvm, and stirring rate at 45 rpm. During fermentation, the concentration of substrate glycerol in the fermentation broth was measured, and glycerol was added according to the glycerol consumption rate to ensure that the glycerol concentration in the fermentation broth was 0.3-25 g / L. The fermentation was completed after 44 hours.

[0142] (ii) The 1,3-propanediol fermentation broth obtained in step (i) is filtered and sterilized and concentrated in sequence to obtain a primary concentrate;

[0143] Ultrafiltration is used for filtration and sterilization, and ultrafiltration is carried out using a ceramic membrane (the filtration pore size of the ceramic membrane is 5nm).

[0144] Concentration is carried out using a multi-effect evaporator, and the process parameters of the multi-effect evaporator are as follows: the vacuum gauge pressures of the first / second / third / fourth effect evaporators are -0.068 MPa / -0.072 MPa / -0.086 MPa / -0.096 MPa, respectively.

[0145] (iii) The concentrate obtained in step (ii) is processed using... Figure 2 The chromatographic separation system shown performs chromatographic separation and desalting. The system comprises six sequentially connected chromatographic columns, and the chromatographic separation and desalting consists of six consecutive repeat cycles. The specific operation procedure for the first repeat cycle is as follows: Figure 3-8 The process is as shown, and subsequent repeat cycles are performed as follows: In two adjacent repeat cycles, the latter repeat cycle is controlled to have the following changes relative to the former repeat cycle: In the first discharge, the chromatographic separation columns for collecting components A and B are switched to the next one along the circulation flow direction; In the second discharge, the chromatographic separation columns for collecting the remaining component B are switched to the next one along the circulation flow direction; After completing 6 repeat cycles, the components A collected multiple times are mixed to obtain the desalting solution;

[0146] The chromatographic separation column uses sodium-type uniform granular gel cation exchange resin.

[0147] In the feeding circulation process, the circulation flow rate is 2.2 BV / h, and the circulation time is 8 min;

[0148] In the feed circulation process, the feed volume of the primary concentrate is 0.1 BV.

[0149] In the first discharge process, the feed volume of the eluent used to discharge component A is 0.16 BV, and the feed volume of the primary concentrate used to discharge component B is 0.1 BV.

[0150] In the second discharge process, the feed volume of the eluent used to push out the remaining component B is 0.15 BV;

[0151] The eluent is water;

[0152] The chromatographic separation operation pressure is 0.25 MPa, and the operating temperature is 50℃.

[0153] (iv) The desalination solution obtained in step (iii) is concentrated to obtain a secondary concentrate, and then the secondary concentrate is purified to obtain 1,3-propanediol; the concentration is carried out using a multi-effect evaporator, and the process parameters of the multi-effect evaporator are: the vacuum gauge pressure of the first / second / third / fourth effect evaporators are -0.065 MPa / -0.07 MPa / -0.085 MPa / -0.095 MPa, respectively;

[0154] The purification process employs distillation, which involves the following steps: Initially, light components such as water and a small amount of BDO are distilled under relatively low reboiler temperature (approximately 80°C) and relatively high operating pressure (approximately 30 mmHg). Once the water distillation is largely complete, the reboiler temperature gradually rises, and continuous feeding begins. The reboiler temperature is maintained at 115±5°C, and the operating pressure at 15±5 mmHg. After the material feeding is complete, the operating pressure is further reduced, and the reboiler temperature continues to rise until the viscosity of the material in the reboiler reaches the required value of 150±5 cp (100°C), at which point distillation is complete. The minimum operating pressure is approximately 5 mmHg, and the maximum temperature can reach 160°C.

[0155] The experimental data are shown in Table 3.

[0156] Table 3. Statistical analysis of chromatographic separation and desalting data of fermentation broth.

[0157]

[0158] Table 3 shows that the ratio of eluent to primary concentrate in the chromatographic separation and desalting process was 3.1:1, achieving a PDO yield of 99% and a total salt removal rate of 93.33%. These product yields and salt removal rates are significantly higher than those of the electrodialysis desalting process. After secondary concentration of the desalting solution, distillation was performed. The residue in the distillation vessel accounted for only 8.98% of the PDO yield, indicating a significant reduction in the residue and an increase in the PDO yield to 99% during the distillation process.

[0159] Comparative Example 1

[0160] The procedure is basically the same as in Example 1, except that: 1. A nanofiltration step is included after ultrafiltration. The nanofiltration membrane used is MWCO500-1000; 2. Chromatographic separation desalination is replaced by electrodialysis desalination. The ion exchange membrane used in electrodialysis is an alloy membrane. The operating temperature of electrodialysis desalination is 35°C. After electrodialysis desalination, the conductivity of the desalination solution is reduced to 2500 μS / cm.

[0161] The experimental data are shown in Table 4.

[0162] Table 4. Statistics on electrodialysis desalination data of fermentation broth

[0163]

[0164] As shown above, this process not only requires an additional nanofiltration step, but also, during electrodialysis desalination, the PDO yield is 95.2%, and the total salt removal rate is 88.5%. After the desalted solution is concentrated, it is distilled. The residue in the distillation vessel accounts for 23.5% of the PDO yield, and the PDO yield during the distillation process is 96%. The residue in the distillation vessel has a high salt content and high viscosity, requiring scraper evaporation to recover the PDO and some glycerol.

[0165] Comparative Example 2

[0166] The process is basically the same as in Example 1, except that the only difference is the use of calcium-type uniform particle gel cation exchange chromatography resin (LX-1850 calcium-type uniform particle gel cation exchange chromatography resin (280-300μm), Xi'an Lanxiao Technology New Material Co., Ltd.).

[0167] The experimental data are shown in Table 5.

[0168] Table 5. Statistics on electrodialysis desalination data of fermentation broth

[0169]

[0170]

[0171] As shown in Table 5, under the condition that the ratio of eluent to primary concentrate in the chromatographic separation and desalting process is 2.4:1, when the resin type is uniform particle gel cation exchange chromatography resin (calcium type), the yield of PDO in the chromatographic separation and desalting process is only 93%, and the total salt removal rate, i.e., the desalting rate, is 91.72%. After the desalting solution is concentrated a second time and then distilled, the residue in the distillation vessel accounts for 14.38% of the PDO yield.

[0172] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for desalting 1,3-propanediol fermentation broth, characterized in that, The desalination method includes: The 1,3-propanediol fermentation broth was sequentially filtered to remove bacteria and concentrated to obtain a primary concentrate. The obtained primary concentrate was subjected to chromatographic separation and desalting using a chromatographic separation system. The chromatographic separation system included n sequentially circulated chromatographic separation columns, where n was an integer greater than or equal to 6. The resin used in the chromatographic separation columns was sodium-type uniform granular gel cation exchange chromatographic resin. The chromatographic separation and desalting includes m consecutive repeating cycles, where m and n are the same; wherein, in each repeating cycle, the following steps are performed sequentially: Feed circulation: A portion of the primary concentrate is circulated into the chromatographic separation system until one chromatographic column is enriched for component A and another chromatographic column is enriched for component B. Component A contains 1,3-propanediol and component B contains salts. First discharge: Eluent is introduced into the inlet of the chromatographic separation column for enriched component A to push component A out of the chromatographic separation column for enriched component A and collect it; A portion of the concentrate is introduced into the inlet of the chromatographic column preceding the column for enriching component B, thereby expelling component B from the column for enriching component B and collecting it; the preceding column is the one preceding the column for enriching component B in the opposite direction of the circulation flow. Second discharge: Eluent is introduced again through the inlet of the first discharge to push out the remaining component B in the chromatographic separation column enriched in the first discharge, and collected; In two adjacent repetition cycles, the latter repetition cycle has the following changes relative to the former repetition cycle: During the first discharge, the chromatographic separation columns collecting components A and B both switched to the next column along the direction of circulation. During the second discharge, the chromatographic separation columns collecting the remaining component B were switched to the next one along the direction of circulation; After completing m repetition cycles, the collected components A from multiple cycles are mixed to obtain a desalination solution; The eluent is water; The chromatographic separation and desalting operation pressure is 0.1-1.0 MPa, and the operating temperature is 20-60℃; In the feed circulation process, the circulation flow rate is 1-6 BV / h, and the feed volume of the primary concentrate is 0.05-0.3 BV. In the first discharge process, the feed volume of the eluent used to discharge component A is 0.1-0.42 BV, and the feed volume of the primary concentrate used to discharge component B is 0.05-0.3 BV. In the second discharge process, the feed volume of the eluent used to push out the remaining component B is 0.06-0.3 BV.

2. The method for desalting 1,3-propanediol fermentation broth according to claim 1, characterized in that, 1,3-Propanediol fermentation broth is produced from renewable biomass by fermentation of bacteria such as Klebsiella pneumoniae, Clostridium, Lemonobacterium, Lactobacillus, Corynebacterium glutamicum, or Escherichia coli, or by fermentation of genetically engineered bacteria of these genera.

3. The method for desalting 1,3-propanediol fermentation broth according to claim 1, characterized in that, The filtration and sterilization process employs ultrafiltration, which uses a ceramic membrane for sterilization and protein removal. The filtration pore size of the ceramic membrane is 5nm-50nm.

4. The method for desalting 1,3-propanediol fermentation broth according to claim 1, characterized in that, The water content of the primary concentrate is controlled between 50wt% and 70wt%.

5. The method for desalting 1,3-propanediol fermentation broth according to claim 1, characterized in that, The chromatographic separation and desalting operation pressure is 0.2-0.5 MPa, and the operating temperature is 25-55℃.

6. The method for desalting 1,3-propanediol fermentation broth according to claim 5, characterized in that, The chromatographic separation and desalting operation pressure is 0.2-0.4 MPa, and the operating temperature is 30-50℃.

7. The method for desalting 1,3-propanediol fermentation broth according to claim 1, characterized in that, When n is 6, the chromatographic separation system includes a first chromatographic separation column, a second chromatographic separation column, a third chromatographic separation column, a fourth chromatographic separation column, a fifth chromatographic separation column, and a sixth chromatographic separation column that are connected in sequence to form a loop. At least one valve is provided between adjacent chromatographic separation columns for communication. The valve is used to control the feed or the eluent and to discharge specific components. The feed cycle time is 6-20 min, and the chromatographic separation column for enriched component A is separated from the chromatographic separation column for enriched component B by 3 chromatographic separation columns.

8. The method for desalting 1,3-propanediol fermentation broth according to claim 1, characterized in that, In the feed circulation process, the circulation flow rate is 2-4 BV / h, and the feed volume of the primary concentrate is 0.08-0.22 BV.

9. The method for desalting 1,3-propanediol fermentation broth according to claim 1, characterized in that, In the first discharge process, the operation of ejecting component A and component B is carried out simultaneously; and during the ejection of component A, the outlet of the next chromatographic column of the enriched component A along the circulation flow direction is closed. During the ejection of component B, the outlet of the chromatographic column enriched for component B is closed in the direction of circulation to the next chromatographic column.

10. The method for desalting 1,3-propanediol fermentation broth according to claim 9, characterized in that, In the first discharge process, the feed volume of the eluent used to discharge component A is 0.08-0.24 BV; the feed volume of the primary concentrate used to discharge component B is 0.08-0.22 BV.

11. The method for desalting 1,3-propanediol fermentation broth according to claim 1, characterized in that, In the second discharge process, during the discharge of the remaining component B, the outlet of the next chromatographic column along the circulation flow direction of the chromatographic column where component B was enriched in the first discharge is closed.

12. The method for desalting 1,3-propanediol fermentation broth according to claim 11, characterized in that, In the second discharge process, the feed volume of the eluent used to push out the remaining component B is 0.08-0.22 BV.

13. The method for desalting 1,3-propanediol fermentation broth according to claim 1, characterized in that, The desalination method also includes the steps of concentrating the desalted liquid to obtain a secondary concentrate and purifying the secondary concentrate. The concentration is carried out by multi-effect evaporation, MVR evaporation or multi-effect distillation, and the water content of the secondary concentrate is 5wt%-45wt%. The purification is carried out by distillation, and the process parameters for distillation are: operating pressure of 5-30 mmHg and distillation column bottom temperature of 80-160℃.

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