Electrodeionization separation and purification method applied to desalination process of bio-based product

Abstract

The invention discloses an electrodeionization separation and purification method applied to a bio-based product desalination process, and belongs to the technical field of biochemical engineering separation. According to the electrodeionization separation and purification method applied to the desalination process of the bio-based product, the advantages of electrodialysis and resin desalination are fused, the resistance between the electrode plates is effectively reduced through the built-in medium containing the ionic groups, then the desalination efficiency driven by current is enhanced, and the production cost is reduced. According to the method, an electrodeionization device is utilized, efficient desalination treatment is carried out on various bio-based products such as saccharides and derivatives thereof, organic acid and organic alcohol, the desalination efficiency generally exceeds 98%, and the unit yield is kept to be 95% or above. In addition, under the configuration of a product flow conveyed across the membrane and a specific membrane group, the technology also shows excellent decolorization performance. The method disclosed by the invention shows wide applicability in desalting treatment of bio-based products, which indicates that the method has a wide development prospect in industrial application.

Description

Technical Field

[0001] The present invention relates to the field of biochemical separation technology, and more particularly to an electrodeionization separation and purification method applied to the desalination process of bio-based products. Background Art

[0002] In the industrial production process of bio-based products, the effective design and optimization of the separation process has become a crucial link, and its efficiency is directly related to the production cost and the feasibility of product commercialization. Compared with traditional chemical separation technology, the biochemical separation process faces more severe systemic challenges due to the complexity of material composition and the uncertainty of the biomanufacturing process. In particular, the desalination of fermentation broth is a common and urgent problem to be solved. In recent decades, scientists have continuously explored and introduced a variety of desalination technologies to meet this challenge. Among them, extraction technology, chromatography technology, membrane treatment technology and electric desalination technology are the most commonly used and effective methods.

[0003] The core of extraction desalination is to utilize the distribution difference between the target organic matter and salt in two immiscible phases. This method has shown great potential for industrial application in the separation and purification of bio-based chemicals such as alcohols and organic acids. Among many technologies, chromatography has become a widely used and mature method due to its low energy consumption, low cost and ability to achieve efficient and fine desalination. However, chromatography also faces some challenges, such as limited saturated adsorption capacity, competitive adsorption between impurities and target purified products, and the need for acid-base regeneration. Membrane separation technology has extremely high value in industrial applications because of its energy saving and low pollution, but separation efficiency and long-term stability are still urgent issues to be solved. Electric-driven desalination technology covers a variety of electrochemical conversion processes, such as electro-oxidation, electro-reduction, electro-flocculation, electro-flotation, electro-deposition, electrodialysis, electrodeionization (EDI), shock electrodialysis (Shock ED), capacitive deionization (CDI) and Faraday electrosorption. In terms of desalination of bio-based fermentation broth using electromotive force, electrodialysis (ED), electrodeionization (EDI) and capacitive deionization (CDI) are the most reported technologies with great development potential.

[0004] EDI technology essentially combines the advantages of electrodialysis technology and resin desalination technology. By filling the gaps between the ion exchange membranes of the electrodialysis system with charged resin particles, a more efficient transmission path is constructed for salt components. This design reduces the resistance between the electrodes, thereby improving production efficiency and product purity. In addition, the water electrolysis reaction accompanying the EDI process generates hydrogen ions and hydroxide ions, which can effectively regenerate the filled resin. Therefore, EDI technology not only overcomes the limitations of electrodialysis in deep desalination, but also greatly reduces the generation of regenerated wastewater during resin desalination. Although a large number of studies have focused on the application of EDI in wastewater treatment and pure water purification, and there are some commercial case reports, patent reports on EDI technology in the field of separation and purification of bio-based chemicals are relatively scarce.

[0005] Therefore, providing an electrodeionization separation and purification method for application in the desalination process of bio-based products is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0006] In view of this, the present invention provides an electrodeionization separation and purification method applied to the desalination process of bio-based products. In view of the lack of versatility and continuity in the desalination process of existing bio-based fermentation products, it is planned to develop electrodeionization technology and apply it to the desalination process of bio-based fermentation products, so as to efficiently and greenly remove the salt components of the fermentation liquid and reduce the process operating costs.

[0007] In order to achieve the above object, the present invention adopts the following technical solution: An electrodeionization separation and purification method applied to the desalination process of a bio-based product, comprising pre-treating a fermentation liquid to obtain a pre-treated fermentation liquid; separating and purifying the pre-treated fermentation liquid using an electrodeionization device; and post-treating the electrodeionization device; The electrodeionization device comprises a membrane stack assembly, a liquid storage tank, a pipeline, a circulating water pump 14, a flow meter 15, a temperature sensor 16, and a pressure meter 17; The liquid storage tanks are respectively a material liquid storage tank 11, a salt concentration liquid storage tank 12, and an electrode liquid storage tank 13; The three circulating water pumps are respectively connected to the material storage tank 11, the salt concentration storage tank 12, and the electrode liquid storage tank 13, and a circulating flow is formed through the pipeline. The fluid flows in the same direction and the fluid flow rate is consistent to maintain no pressure difference in the membrane stack. The flow meter 15 is a rotor flow meter, and the monitoring position is located in the pipeline between the outlet of the material storage tank 11 and the inlet of the membrane stack assembly; The temperature sensor 16 is a built-in sensor, and the monitoring position is located in the pipeline between the outlet of the membrane stack assembly and the inlet of the material storage tank 11 to control the ion exchange membrane to be at a safe operating temperature; the safe operating temperature should be between 10 and 40°C.

[0008] The monitoring position of the pressure meter 17 is located in the pipeline between the temperature sensor 16 and the material storage tank 11; The membrane stack assembly consists of an ion exchange membrane group, a filling medium 6, a positive electrode plate 7, a negative electrode plate 8, a supporting spacer 9, and a silicone seal 10; the ion exchange membrane group is composed of a plurality of pairs of "cation exchange membranes 4-anion exchange membranes or bipolar membranes 5" alternately, the membranes are sealed by silicone seals 10 and filled with filling medium 6 to form a material chamber 1 and a salt concentration chamber 2; cation exchange membranes 4 are loaded near the positive electrode plate 7 and the negative electrode plate 8, and a supporting spacer is loaded between the positive electrode plate 7 and the negative electrode plate 8 and the cation exchange membrane to form an electrode liquid chamber 3; the material storage tank 11 and the material chamber 1 are circulated by the pipeline "branching first and then merging"; the salt concentration storage tank 12 and the salt concentration chamber 2 are circulated by the pipeline "branching first and then merging"; the electrode liquid in the electrode liquid storage tank 13 circulates through the electrode liquid chambers 3 at both ends; the anode surface of the bipolar membrane faces the negative electrode plate 8, and the cathode surface faces the positive electrode plate 7.

[0009] Further, the filling medium is an ion exchange resin; The filling form of the filling medium is "cis" layered, "trans" layered, disordered mixed or "sandwich"; the "cis" layered filling form is that the cation exchange resin faces the positive electrode plate, and the anion exchange resin faces the negative electrode plate; the "trans" layered filling form is that the anion exchange resin faces the positive electrode plate, and the cation exchange resin faces the negative electrode plate; the disordered mixed filling form is that the anion exchange resin and the cation exchange resin are randomly filled; the "sandwich" filling form is that the anion exchange resin and the cation exchange resin are both filled in a right-angled triangular prism form. The filling medium is in the shape of spheres (macroporous or gel-type ion exchange resin beads), fibers, round crystal flakes (resin flakes obtained by crosslinking resin beads with a crosslinking agent), or hollow sheets (resin flakes with a hollow structure synthesized by a template sacrificial method or the like).

[0010] Furthermore, the materials of the positive electrode plate and the negative electrode plate are graphite electrodes, lead electrodes or stainless steel electrodes; the voltage range of the electrode plate is 5~100V; the electrode plate has a voltage output mode and a current output mode; the voltage or current output mode is gradient, pulse or stable; the electrode plate has a positive and negative electrode reversal function.

[0011] Furthermore, the pretreated fermentation broth is a fermentation broth of sugars and their derivatives, organic acids or organic alcohols.

[0012] Further, the fermentation broth is pre-treated, including flocculation, microfiltration, centrifugation, ultrafiltration, pH adjustment, decolorization, and evaporation concentration.

[0013] The salt concentration storage tank and the electrode liquid storage tank are filled with electrolyte liquid. The electrolyte liquid includes but is not limited to: sodium chloride solution, potassium chloride solution, sodium sulfate solution, potassium sulfate solution, sodium hydroxide solution, potassium hydroxide solution. The concentration of the electrolyte liquid is 0.1-0.25 mol / L.

[0014] Each circulating water pump is connected to the material storage tank, salt concentration storage tank, and electrode liquid storage tank respectively, and a circulating flow is formed through the pipeline. The fluid flows in the same direction, and the fluid flow rate is 1~10L / h. Each circulating flow requires a consistent flow rate to maintain no pressure difference in the membrane stack.

[0015] The filling amount of the filling medium is 100-1000 grams of resin per square meter of ion exchange membrane.

[0016] The post-treatment technology comprises the following steps: rinsing with deionized water of 3 to 5 times the volume of the fermentation liquid; adding 0.1 to 1 mol / L sodium chloride aqueous solution to the material chamber, salt concentration chamber, and electrode chamber, respectively, and running in the electric field of the reverse electrode for 0.5 to 1 hour; and rinsing again with deionized water of 1 to 5 times the volume of the sodium chloride aqueous solution.

[0017] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses an electrodeionization separation and purification method applied to the desalination process of bio-based products, creating a new electrodeionization technology that integrates resin chromatography and electrodialysis principles, which is specially designed for the desalination needs of bio-based fermentation products. Specifically, the present invention innovatively embeds the resin carrying ionic charge groups into the electrodialysis membrane stack assembly in a certain form, and the stacking configuration of the membrane stack is flexibly adjusted according to the characteristics of the actual bio-fermentation product. An appropriate electric field is applied to the assembled electrodeionization membrane stack assembly to accelerate the migration rate of ions. In this process, the charge groups of the resin act as a "fast channel" for the migration of salt in the fermentation broth, greatly reducing the resistance between the electrode plates. In addition, in different membrane stack assembly designs, different bio-based products have different migration properties, so the electrodeionization technology also has a certain decolorization ability.

[0018] In practical applications, this technology has shown two significant advantages: on the one hand, in the process of continuous desalination of fermentation broth, it effectively improves the current utilization efficiency and significantly reduces the purification cost of the product; on the other hand, in the process of batch production of fermentation broth desalination, even if the current decreases as the concentration of salt components decreases, this technology can still maintain a high current level to achieve fine desalination, making up for the shortcomings of traditional electrodialysis technology in treating low-concentration salts. In addition, by introducing electrode reversal technology, the present invention successfully solves the problem of pollutant accumulation in the desalination process, thereby significantly extending the service life of the ion exchange membrane and further reducing material costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0020] Figure 1 The accompanying drawing shows the stacking form of the membrane group used in the bio-based fermentation liquid electrodeionization process of the present invention; Among them, 1: material chamber; 2: salt concentration chamber; 3: electrode liquid chamber; 4: cation exchange membrane; 5: anion exchange membrane or bipolar membrane; 6: filling medium; 7: positive electrode plate; 8: negative electrode plate; 9: support screen; 10: silicone sealing ring; 11: material storage tank; 12: salt concentration storage tank; 13: electrode liquid storage tank; 14: circulating water pump; 15: flow meter; 16: temperature sensor; 17: pressure gauge.

[0021] Figure 2 The accompanying drawing shows the filling form of the medium in the electrodeionization device of the present invention; Among them, A: "cis" layered; B: "trans" layered; C: disordered mixture; D: "sandwich" shape; 4: cation exchange membrane; 5: anion exchange membrane or bipolar membrane; 18: cation exchange resin; 19: anion exchange resin. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Example 1 The recombinant Corynebacterium glutamicum ΔnagA / BΔ1dhΔcg12642Δzwf-pec-BsS-B-CeA strain provided by the patent CN114250188A was used for fermentation in a 5L fermenter to obtain an N-acetylglucosamine fermentation liquid with a concentration of 120 g / L. The fermentation liquid was pre-treated, specifically including: firstly, flocculation and microfiltration were performed to obtain a clarified N-acetylglucosamine sterilized liquid; then, concentration and decolorization were performed to finally obtain a clarified 3.2L N-acetylglucosamine decolorized liquid (with a concentration of 150 g / L) with a conductivity of 30 mS / cm, which was used as the raw liquid 1 for electrodeionization treatment. The raw material solution 1 was then treated with 5% hydrochloric acid at 80°C and 200 rpm for 7 hours to remove the N-acetyl group, and after cooling to room temperature, it was neutralized to pH 6 with 1 mol / L sodium hydroxide to obtain 3.4 L of glucosamine hydrochloride solution (concentration of 130 g / L) with a conductivity of 40 mS / cm, which was used as the raw material solution 2 for electrodeionization treatment.

[0024] The pre-treated fermentation liquid is separated and purified by an electrodeionization device, specifically including: in the electrodeionization membrane stack component, such as Figure 1 As shown in the figure, 5 pairs of "yin-yang" alternately stacked ion exchange membranes are loaded, and each pair of ion exchange membranes forms a chamber through Figure 2 The disordered mixed form shown in C, the filling medium is spherical ion exchange resin, and the filling amount of the resin is 500 grams per square meter of ion exchange membrane. After the filling medium is added between each pair of ion exchange membranes and sealed by a silicone sealing ring, a material chamber and a salt concentration chamber are formed; cation exchange membranes are loaded near the positive electrode plate and the negative electrode plate, and a support screen is loaded between the positive electrode plate and the negative electrode plate and the cation exchange membrane to form an electrode liquid chamber; the material storage tank and the material chamber are circulated through the pipeline "branching first and then merging" for material circulation; the salt concentration storage tank and the salt concentration chamber are circulated through the pipeline "branching first and then merging" for material circulation; the electrode liquid in the electrode liquid storage tank is circulated through the electrode liquid chambers at both ends. The material of the positive electrode plate and the negative electrode plate is graphite electrode.

[0025] The material storage tank is filled with raw liquid 1 or raw liquid 2, the salt concentration storage tank is filled with 0.1mol / L sodium chloride solution, and the extreme liquid storage tank is filled with 0.25mol / L sodium sulfate solution. During operation, the circulating water pumps of the three storage tanks are turned on at the same time, and circulated at a flow rate of 1L / h until all bubbles in the discharge pipeline are exhausted and the flow rate is stable and there is no pressure difference in the chamber; the electrode plate increases the voltage to 10V, and the stable voltage output mode runs for 8h (that is, when the conductivity of the circulating raw material liquid is 0.2mS / cm) and then stops. Finally, 2.76L of N-acetylglucosamine solution (concentration of 172.5g / L) and 2.91L of glucosamine hydrochloride solution (concentration of 149.5g / L) can be obtained.

[0026] Formula 1 can be used to calculate the desalination rate of raw material solution 1 or raw material solution 2 by electrodeionization, and formula 2 can be used to calculate the process yield of raw material solution 1 or raw material solution 2 by electrodeionization. Finally, the desalination rate of raw material solution 1 in the electrodeionization process is 99.3%, and the yield is 99.2%; the desalination rate of raw material solution 2 in the electrodeionization process is 99.5%, and the yield is 98.4%.

[0027] Formula 1: (Conductivity of the solution in the material storage tank that has not been desalinated by electrodeionization - conductivity of the solution in the material storage tank that has been desalinated by electrodeionization) / conductivity of the solution in the material storage tank that has not been desalinated by electrodeionization × 100%.

[0028] Formula 2: (N-acetylglucosamine concentration or glucosamine hydrochloride concentration in the material storage tank after electrodeionization desalination × the volume of the material storage tank after electrodeionization desalination) / (N-acetylglucosamine concentration or glucosamine hydrochloride concentration in the material storage tank without electrodeionization desalination × the volume of the material storage tank without electrodeionization desalination) × 100%.

[0029] The electrodeionization device is post-processed, specifically including: draining the residual liquid from each storage tank and pipeline, rinsing with 3 times of clean water, and running for 1 hour in a reversed electric field with the same voltage value with 0.1 mol / L sodium chloride solution. After the operation, rinse with 1 times of clean water, and fill the membrane stack assembly with clean water for storage.

[0030] Example 2 The recombinant E. coli VT03 strain (E. coli U5 carrying pCDF-tbytp and pACYC-fnp plasmids) provided by the patent CN115873881A was used for fermentation in a 5L fermenter to obtain a 1,3-butanediol fermentation broth with a concentration of 30 g / L. The fermentation broth was pre-treated, specifically including: firstly, flocculation and microfiltration were performed to obtain a clarified 1,3-butanediol sterilization solution; then, concentration and decolorization were performed to finally obtain a clarified 1.58L 1,3-butanediol decolorization solution (concentration of 80 g / L) with a conductivity of 16.5 mS / cm, which was used as the raw material solution for electrodeionization treatment.

[0031] The pre-treated fermentation liquid is separated and purified by an electrodeionization device, specifically including: in the electrodeionization membrane stack component, such as Figure 1 As shown in the figure, 5 pairs of "yin-yang" alternately stacked ion exchange membranes are loaded, and each pair of ion exchange membranes forms a chamber through Figure 2The "sandwich-shaped" mixed form shown in D has a filling medium in the shape of a fiber-type ion exchange resin, and the filling amount of the resin is 400 grams per square meter of ion exchange membrane. After adding the filling medium between each pair of ion exchange membranes and sealing them with a silicone seal ring, a material chamber and a salt concentration chamber are formed; cation exchange membranes are loaded near the positive electrode plate and the negative electrode plate, and a support screen is loaded between the positive electrode plate and the negative electrode plate and the cation exchange membrane to form an electrode liquid chamber; the material storage tank and the material chamber are circulated through the pipeline "branching first and then merging" for material circulation; the salt concentration storage tank and the salt concentration chamber are circulated through the pipeline "branching first and then merging" for material circulation; the electrode liquid in the electrode liquid storage tank is circulated through the electrode liquid chambers at both ends. The material of the positive electrode plate and the negative electrode plate is lead electrode.

[0032] The material storage tank is filled with raw liquid, the salt concentration storage tank is filled with 0.15mol / L potassium chloride solution, and the extreme liquid storage tank is filled with 0.25mol / L potassium sulfate solution. During operation, the circulating water pumps of the three storage tanks are turned on at the same time, and circulated at a flow rate of 5L / h until all bubbles in the discharge pipeline are exhausted and the flow rate is stable and there is no pressure difference in the chamber; the electrode plate increases the voltage to 12V, and the pulse voltage output mode runs for 6h (when the conductivity of the circulating raw material liquid is 0.1mS / cm) and then stops. Finally, 1.39L of 1,3-butanediol solution (concentration is 90g / L) can be obtained.

[0033] Formula 1 can be used to calculate the desalination rate of the raw material liquid treated by the electrodeionization method, and Formula 2 can be used to calculate the process yield of the raw material liquid treated by the electrodeionization method. The final desalination rate of the raw material liquid electrodeionization process is 99.4%, and the yield is 99.0%.

[0034] Formula 1: (Conductivity of the solution in the material storage tank that has not been desalinated by electrodeionization - conductivity of the solution in the material storage tank that has been desalinated by electrodeionization) / conductivity of the solution in the material storage tank that has not been desalinated by electrodeionization × 100%.

[0035] Formula 2: (1,3-butanediol concentration in the material storage tank that has undergone electrodeionization desalination × the volume in the material storage tank that has undergone electrodeionization desalination) / (1,3-butanediol concentration in the material storage tank that has not undergone electrodeionization desalination × the volume in the material storage tank that has not undergone electrodeionization desalination) × 100%.

[0036] The electrodeionization device is post-processed, specifically including: draining the residual liquid from each storage tank and pipeline, rinsing with 4 times of clean water, and running for 0.5 hours in a reversed electric field with the same voltage value with 0.5 mol / L sodium chloride solution. After the operation, rinse with 3 times of clean water, and fill the membrane stack assembly with clean water for storage.

[0037] Example 3 The recombinant Escherichia coli BW-PA-pby-PR-pyM strain provided by the patent CN114276970A was used for fermentation in a 5L fermenter to obtain a 1,3-propylene glycol fermentation broth with a concentration of 20g / L. The fermentation broth was pre-treated, specifically including: firstly, flocculation and microfiltration were performed to obtain a clarified 1,3-propylene glycol sterilization solution; then, concentration and decolorization were performed to finally obtain a clarified 2.5L 1,3-propylene glycol decolorization solution (with a concentration of 33.8g / L) with a conductivity of 11mS / cm, which was used as the raw material solution for electrodeionization treatment.

[0038] The pre-treated fermentation liquid is separated and purified by an electrodeionization device, specifically including: in the electrodeionization membrane stack component, such as Figure 1 As shown in the figure, 5 pairs of "yin-yang" alternately stacked ion exchange membranes are loaded, and each pair of ion exchange membranes forms a chamber through Figure 2 The "cis" layered mixed form shown in A has a filling medium in the shape of a round crystal thin sheet type ion exchange resin, and the filling amount of the resin is 300 grams per square meter of ion exchange membrane. After adding the filling medium between each pair of ion exchange membranes and sealing them with a silicone seal ring, a material chamber and a salt concentration chamber are formed; cation exchange membranes are loaded near the positive electrode plate and the negative electrode plate, and a support screen is loaded between the positive electrode plate and the negative electrode plate and the cation exchange membrane to form an electrode liquid chamber; the material storage tank and the material chamber are circulated through the pipeline "branching first and then merging" for material circulation; the salt concentration storage tank and the salt concentration chamber are circulated through the pipeline "branching first and then merging" for material circulation; the electrode liquid in the electrode liquid storage tank is circulated through the electrode liquid chambers at both ends. The material of the positive electrode plate and the negative electrode plate is stainless steel electrode.

[0039] The material storage tank is filled with raw liquid, the salt concentration storage tank is filled with 0.1mol / L sodium chloride solution, and the extreme liquid storage tank is filled with 0.2mol / L sodium sulfate solution. During operation, the circulating water pumps of the three storage tanks are turned on at the same time, and circulated at a flow rate of 10L / h until all bubbles in the discharge pipeline are exhausted and the flow rate is stable and there is no pressure difference in the chamber; the electrode plate increases the voltage to 10V, and the gradient voltage output mode runs for 4.5h (when the conductivity of the circulating raw material liquid is 0.2mS / cm) and then stops. Finally, 2.15L of 1,3-propylene glycol solution (concentration of 38.5g / L) can be obtained.

[0040] Formula 1 can be used to calculate the desalination rate of the raw material liquid treated by the electrodeionization method, and Formula 2 can be used to calculate the process yield of the raw material liquid treated by the electrodeionization method. The final desalination rate of the raw material liquid electrodeionization process is 98.2%, and the yield is 98.0%.

[0041] Formula 1: (Conductivity of the solution in the material storage tank that has not been desalinated by electrodeionization - conductivity of the solution in the material storage tank that has been desalinated by electrodeionization) / conductivity of the solution in the material storage tank that has not been desalinated by electrodeionization × 100%.

[0042] Formula 2: (1,3-propylene glycol concentration in the material storage tank that has undergone electrodeionization desalination × the volume in the material storage tank that has undergone electrodeionization desalination) / (1,3-propylene glycol concentration in the material storage tank that has not undergone electrodeionization desalination × the volume in the material storage tank that has not undergone electrodeionization desalination) × 100%.

[0043] The electrodeionization device is post-processed, specifically including: draining the residual liquid from each storage tank and pipeline, rinsing with 5 times of clean water, and running for 1 hour in a reversed electric field with the same voltage value with 1 mol / L sodium chloride solution. After the operation, rinse with 5 times of clean water and fill the membrane stack assembly with clean water for storage.

[0044] Example 4 Using ethylene provided by the patent CN114394882A as raw material, under acidic conditions, it is subjected to oxidation and hydration reaction with hydrogen peroxide and titanium silicon molecular sieve to obtain 3L of ethylene glycol solution (concentration of 40g / L). The conductivity of the ethylene glycol solution is 24.5mS / cm, which is used as the raw material solution for electrodeionization treatment.

[0045] The pre-treated fermentation liquid is separated and purified by an electrodeionization device, specifically including: in the electrodeionization membrane stack component, such as Figure 1 As shown in the figure, 5 pairs of "yin-yang" alternately stacked ion exchange membranes are loaded, and each pair of ion exchange membranes forms a chamber through Figure 2 The "trans" layered mixed form shown in B has a filling medium in the shape of a hollow sheet-type ion exchange resin, and the filling amount of the resin is 300 grams per square meter of ion exchange membrane. After adding the filling medium between each pair of ion exchange membranes and sealing them with a silicone seal ring, a material chamber and a salt concentration chamber are formed; cation exchange membranes are loaded near the positive electrode plate and the negative electrode plate, and a support screen is loaded between the positive electrode plate and the negative electrode plate and the cation exchange membrane to form an electrode liquid chamber; the material storage tank and the material chamber are circulated through the pipeline "branching first and then merging" for material circulation; the salt concentration storage tank and the salt concentration chamber are circulated through the pipeline "branching first and then merging" for material circulation; the electrode liquid in the electrode liquid storage tank is circulated through the electrode liquid chambers at both ends. The material of the positive electrode plate and the negative electrode plate is graphite electrode.

[0046] The material storage tank is filled with raw liquid, the salt concentration storage tank is filled with 0.15mol / L sodium chloride solution, and the extreme liquid storage tank is filled with 0.25mol / L sodium sulfate solution. During operation, the circulating water pumps of the three storage tanks are turned on at the same time, and circulated at a flow rate of 5L / h until all bubbles in the discharge pipeline are exhausted and the flow rate is stable and there is no pressure difference in the chamber; the electrode plate increases the voltage to 10V, and the stable voltage output mode runs for 8h (when the conductivity of the circulating raw material liquid is 0.2mS / cm) and then stops. Finally, 2.5L of ethylene glycol solution (concentration of 46g / L) can be obtained.

[0047] Formula 1 can be used to calculate the desalination rate of the raw material liquid treated by the electrodeionization method, and Formula 2 can be used to calculate the process yield of the raw material liquid treated by the electrodeionization method. The final desalination rate of the raw material liquid electrodeionization process is 99.2%, and the yield is 95.8%.

[0048] Formula 1: (Conductivity of the solution in the material storage tank that has not been desalinated by electrodeionization ─ Conductivity of the solution in the material storage tank that has been desalinated by electrodeionization) / Conductivity of the solution in the material storage tank that has not been desalinated by electrodeionization × 100%.

[0049] Formula 2: (ethylene glycol concentration in the material storage tank that has undergone electrodeionization desalination × the volume in the material storage tank that has undergone electrodeionization desalination) / (ethylene glycol concentration in the material storage tank that has not undergone electrodeionization desalination × the volume in the material storage tank that has not undergone electrodeionization desalination) × 100%.

[0050] The electrodeionization device is post-processed, specifically including: draining the residual liquid from each storage tank and pipeline, rinsing with 3 times of clean water, and running for 1 hour in a reversed electric field with the same voltage value with 0.1 mol / L sodium chloride solution. After the operation, rinse with 1 times of clean water, and fill the membrane stack assembly with clean water for storage.

[0051] Example 5 Bacillus coagulans CICIMB1821 was used for fermentation in a 5L fermenter to obtain a sodium L-lactate fermentation liquid with a concentration of 80 g / L. The specific fermentation process was as follows: the straw was subjected to hydrochloric acid-assisted gas explosion for 1 h, and cellulase was added to the substrate straw at 30 FPU / g to obtain a fermentation substrate with a sugar concentration higher than 150 g / L; the seed liquid inoculation amount was 10% of the total fermentation volume, and synchronous saccharification and fermentation were carried out at 50°C after inoculation; sodium carbonate was used as a neutralizer during the fermentation process to control the fermentation pH at 5.6; after 96 h of fermentation, the corresponding sodium L-lactate fermentation liquid was finally obtained.

[0052] The fermentation broth was pretreated, specifically including: firstly, obtaining a clarified L-lactate sterilized solution by microfiltration; then, concentrating and decolorizing, finally obtaining 3.23 L of clarified L-lactate decolorized solution (concentration of 100 g / L) with a conductivity of 100 mS / cm and an absorbance of 5 Abs at 261 nm, which was used as the raw material solution for electrodeionization treatment.

[0053] The pre-treated fermentation liquid is separated and purified by an electrodeionization device, specifically including: in the electrodeionization membrane stack component, such as Figure 1 As shown in the figure, 5 pairs of "yin-yang" alternately stacked ion exchange membranes are loaded, and each pair of ion exchange membranes forms a chamber through Figure 2The disordered mixed form shown in C, the filling medium is spherical ion exchange resin, and the filling amount of the resin is 600 grams per square meter of ion exchange membrane. After the filling medium is added between each pair of ion exchange membranes and sealed by a silicone seal ring, a material chamber and a salt concentration chamber are formed; cation exchange membranes are loaded near the positive electrode plate and the negative electrode plate, and a support screen is loaded between the positive electrode plate and the negative electrode plate and the cation exchange membrane to form an electrode liquid chamber; the material storage tank and the material chamber are circulated through the pipeline "branching first and then merging" for material circulation; the salt concentration storage tank and the salt concentration chamber are circulated through the pipeline "branching first and then merging" for material circulation; the electrode liquid in the electrode liquid storage tank is circulated through the electrode liquid chambers at both ends. The material of the positive electrode plate and the negative electrode plate is lead electrode.

[0054] The material storage tank is filled with raw liquid, the salt concentration storage tank is filled with 0.01mol / L sodium hydroxide solution, and the extreme liquid storage tank is filled with 0.25mol / L sodium sulfate solution. During operation, the circulating water pumps of the three storage tanks are turned on at the same time, and circulated at a flow rate of 1L / h until all bubbles in the discharge pipeline are exhausted and the flow rate is stable and there is no pressure difference in the chamber; the electrode plate increases the voltage to 6V, and the pulse voltage output mode stops after running for 12h (when the conductivity of the circulating raw liquid is 1mS / cm). At this time, sodium lactate and other salt components of the fermentation broth transfer across the membrane and are enriched in the salt concentration chamber, and finally 2.85L of L-sodium lactate solution (concentration of 112g / L) is obtained in the salt concentration storage tank, and its absorbance is 0.085Abs.

[0055] Formula 1 can be used to calculate the process yield of the raw material liquid treated by electrodeionization, and Formula 2 can be used to calculate the decolorization rate of the raw material liquid treated by electrodeionization. The final yield of the process is 98.8%, and the decolorization rate is 98.3%.

[0056] Formula 1: (Concentration of sodium L-lactate desalted by electrodeionization in the salt concentration tank × volume of solution desalted by electrodeionization in the salt concentration tank) / (Concentration of sodium L-lactate not desalted by electrodeionization in the material tank × volume of solution not desalted by electrodeionization in the material tank) × 100%.

[0057] Formula 2: Difference in absorbance at 261 nm between the initial raw material solution and the solution in the salt concentration storage tank after electrodeionization treatment / absorbance at 261 nm of the initial raw material solution × 100%.

[0058] The electrodeionization device is post-processed, specifically including: draining the residual liquid from each storage tank and pipeline, rinsing with 4 times of clean water, and running for 0.5 hours in a reversed electric field with the same voltage value with 0.5 mol / L sodium chloride solution. After the operation, rinse with 3 times of clean water, and fill the membrane stack assembly with clean water for storage.

[0059] Example 6 2.85 L of L-sodium lactate solution (concentration of 112 g / L) enriched in the salt concentration chamber of Example 5 was used as the raw solution for electrodeionization treatment, and its conductivity was 84.5 mS / cm and its sodium ion concentration was 112 g / L.

[0060] The pre-treated fermentation liquid is separated and purified by an electrodeionization device, specifically including: in the electrodeionization membrane stack component, such as Figure 1 As shown in FIG. 1 , five pairs of "bipolar membrane-cation exchange membrane" alternately stacked ion exchange membranes are loaded, and each pair of ion exchange membranes forms a chamber through Figure 2 In the disordered mixed form shown in C, the filling medium is spherical ion exchange resin, and the filling amount of the resin is 600 grams per square meter of ion exchange membrane. After the filling medium is added between each pair of ion exchange membranes and sealed by a silicone sealing ring, a material chamber and a salt concentration chamber are formed; cation exchange membranes are loaded near the positive electrode plate and the negative electrode plate, and a support screen is loaded between the positive electrode plate and the negative electrode plate and the cation exchange membrane, and an electrode liquid chamber is formed, and the anode surface of the bipolar membrane faces the negative electrode plate, and the cathode surface faces the anode positive electrode plate; the material storage tank and the material chamber are circulated through the pipeline "branching first and then merging" for material circulation; the salt concentration storage tank and the salt concentration chamber are circulated through the pipeline "branching first and then merging" for material circulation; the electrode liquid in the electrode liquid storage tank circulates through the electrode liquid chambers at both ends. The material of the positive electrode plate and the negative electrode plate is stainless steel electrode.

[0061] The material storage tank is filled with raw liquid, the salt concentration storage tank is filled with 0.1mol / L sodium chloride aqueous solution, and the extreme liquid storage tank is filled with 0.25mol / L sodium sulfate aqueous solution. During operation, the circulating water pumps of the three storage tanks are turned on at the same time, and circulated at a flow rate of 5L / h until all bubbles in the discharge pipeline are discharged and the flow rate is stable and there is no pressure difference in the critical chamber; the electrode plate increases the voltage to 6V, and the stable voltage output mode runs for 16h (when the conductivity of the circulating fermentation liquid no longer changes) and then stops. At this time, the sodium ions and other salt components of L-sodium lactate have completely migrated across the membrane to the salt concentration chamber, and the hydrogen ions generated by the bipolar membrane ionizing water molecules convert L-sodium lactate into L-lactic acid, thereby realizing the separation and purification of L-lactic acid, and finally obtaining 2.84L of L-lactic acid solution (concentration of 112g / L) in the material storage tank, and its sodium ion concentration is 0.6g / L.

[0062] Formula 1 can be used to calculate the process yield of the raw material liquid treated by electrodeionization, and Formula 2 can be used to calculate the sodium ion removal rate of the raw material liquid treated by electrodeionization. The final yield of the process is 99.6%, and the sodium ion removal rate is 99.5%.

[0063] Formula 1: (Concentration of L-lactic acid in the material storage tank after electrodeionization desalination × volume of solution in the material storage tank after electrodeionization desalination) / (Concentration of L-lactic acid in the material storage tank without electrodeionization desalination × volume of solution in the material storage tank without electrodeionization desalination).

[0064] Formula 2: 100% - (the sodium ion concentration in the material storage tank that has been desalted by electrodeionization × the volume of the solution in the material storage tank that has been desalted by electrodeionization) / (the sodium ion concentration in the material storage tank that has not been desalted by electrodeionization × the volume of the solution in the material storage tank that has not been desalted by electrodeionization) × 100%.

[0065] The electrodeionization device is post-processed, specifically including: draining the residual liquid from each storage tank and pipeline, rinsing with 5 times of clean water, and running for 0.5 hours in a reversed electric field with the same voltage value with 1 mol / L sodium chloride solution. After the operation, rinse with 5 times of clean water, and fill the membrane stack assembly with clean water for storage.

[0066] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electrodeionization separation and purification method for bio-based product desalination process, characterized in that: The method comprises pre-treating the fermentation liquid to obtain the pre-treated fermentation liquid; Separating and purifying the pre-treated fermentation liquid using an electrodeionization device; post-treating the electrodeionization device; The electrodeionization device comprises a membrane stack assembly, a liquid storage tank, a pipeline, a circulating water pump (14), a flow meter (15), a temperature sensor (16), and a pressure meter (17); The liquid storage tanks are respectively a material liquid storage tank (11), a salt concentration liquid storage tank (12), and an electrode liquid storage tank (13); The three circulating water pumps are respectively connected to the material storage tank (11), the salt concentration storage tank (12), and the electrode liquid storage tank (13), and a circulating flow is formed through the pipeline, and the fluid flows in the same direction and the fluid flow rate is consistent; The flow meter (15) is a rotor flow meter, and the monitoring position is located in the pipeline between the outlet of the material storage tank (11) and the inlet of the membrane stack assembly; The temperature sensor (16) is a built-in sensor, and the monitoring position is located in the pipeline between the outlet of the membrane stack assembly and the inlet of the material storage tank (11); The monitoring position of the pressure meter (17) is located in the pipeline between the temperature sensor (16) and the material storage tank (11); The membrane stack assembly is composed of an ion exchange membrane group, a filling medium (6), a positive electrode plate (7), a negative electrode plate (8), a supporting screen (9), and a silicone seal ring (10); the ion exchange membrane group is composed of a plurality of pairs of "cation exchange membranes (4)-anion exchange membranes or bipolar membranes (5)" alternately, the membranes are sealed by silicone seal rings (10) and the filling medium (6) is added to form a material chamber (1) and a salt concentration chamber (2); the cation exchange membranes (4) are loaded near the positive electrode plate (7) and the negative electrode plate (8), A supporting screen is loaded between the positive electrode plate (7) and the negative electrode plate (8) and the cation exchange membrane to form an electrode liquid chamber (3); the material storage tank (11) and the material chamber (1) are subjected to material circulation by "branching first and then merging" through a pipeline; the salt concentration storage tank (12) and the salt concentration chamber (2) are subjected to material circulation by "branching first and then merging" through a pipeline; the electrode liquid in the electrode liquid storage tank (13) is circulated through the electrode liquid chambers (3) at both ends; and the bipolar membrane is loaded with the anode surface facing the negative electrode plate (8) and the cathode surface facing the positive electrode plate (7).

2. The method for electro-deionization separation and purification applied to the desalination process of bio-based products according to claim 1, characterized in that: The filling medium is an ion exchange resin; The filling form of the filling medium is "cis" layered, "trans" layered, disordered mixed or "sandwich"; the "cis" layered filling form is that the cation exchange resin faces the positive electrode plate, and the anion exchange resin faces the negative electrode plate; the "trans" layered filling form is that the anion exchange resin faces the positive electrode plate, and the cation exchange resin faces the negative electrode plate; the disordered mixed filling form is that the anion exchange resin and the cation exchange resin are randomly filled; the "sandwich" filling form is that the anion exchange resin and the cation exchange resin are both filled in a right-angled triangular prism form. The filling medium is in the shape of a sphere, a fiber, a round crystal sheet or a hollow sheet.

3. The method for electro-deionization separation and purification applied to the desalination process of bio-based products according to claim 1, characterized in that: The materials of the positive electrode plate and the negative electrode plate are graphite electrodes, lead electrodes or stainless steel electrodes; the voltage range of the electrode plate is 5~100V; the electrode plate has a voltage output mode and a current output mode; the voltage or current output mode is gradient, pulse or stable; the electrode plate has a positive and negative electrode reversal function.

4. The method for electro-deionization separation and purification applied to the desalination process of bio-based products according to claim 1, characterized in that: The pretreated fermentation broth is a fermentation broth of sugars and their derivatives, organic acids or organic alcohols.

5. The method for electro-deionization separation and purification applied to the desalination process of bio-based products according to claim 1, characterized in that: The fermentation broth is pre-treated, including flocculation, microfiltration, centrifugation, ultrafiltration, pH adjustment, decolorization, and evaporation concentration.

6. The method for electro-deionization separation and purification applied to the desalination process of bio-based products according to claim 1, characterized in that: The salt concentration storage tank and the electrode liquid storage tank are filled with electrolyte liquid; the electrolyte liquid is sodium chloride solution, potassium chloride solution, sodium sulfate solution, potassium sulfate solution, sodium hydroxide solution or potassium hydroxide solution; the concentration of the electrolyte liquid is 0.1-0.25 mol / L.

7. The method for electro-deionization separation and purification applied to the desalination process of bio-based products according to claim 1, characterized in that: The fluid flow rate is 1-10 L / h.

8. The method for electro-deionization separation and purification applied to the desalination process of bio-based products according to claim 1, characterized in that: Post-process the electrodeionization device: rinse with deionized water 3 to 5 times the volume of the fermentation liquid; add 0.1 to 1 mol / L sodium chloride aqueous solution to the material chamber, salt concentration chamber, and electrode chamber, respectively, and run in the electric field of the reverse electrode for 0.5 to 1 h; rinse again with deionized water 1 to 5 times the volume of the sodium chloride aqueous solution.

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