Reutilization method of erythritol nanofiltration membrane concentrated phase

Abstract

The invention discloses a recycling method of an erythritol nanofiltration membrane concentrated phase, and belongs to the technical field of erythritol nanofiltration membrane concentrated phase treatment. The invention discloses a recycling method of an erythritol nanofiltration membrane concentrated phase. The recycling method comprises the following steps: decolorizing the erythritol nanofiltration membrane concentrated phase by using a plate frame, performing ion exchange desalination, adjusting the pH value, adding saccharifying enzyme for reaction, detecting indexes and recycling. According to the method disclosed by the invention, the light transmittance of the erythritol nanofiltration membrane concentrated phase is improved to be more than 50% by means of decoloration, ion exchange desalination, saccharifying enzyme saccharification and the like, more than 95% of inorganic salt is removed, and more than 90% of erythritol is retained; more than 95% of reducing sugar is converted into glucose, the yield of erythritol is increased by more than 80g / L, and secondary utilization of wastes and cost saving are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of the concentrated phase treatment of erythritol nanofiltration membranes, and more specifically, to a method for reusing the concentrated phase of erythritol nanofiltration membranes. Background Art

[0002] During the production of erythritol by the fermentation method, nanofiltration membrane filtration is an important separation and purification step. The nanofiltration membrane has a specific cut-off molecular weight, generally 200 - 1000 daltons. When the erythritol fermentation broth is eluted and filtered through the nanofiltration membrane, the part of the liquid that is retained by the nanofiltration membrane and cannot pass through the membrane forms the concentrated phase of the nanofiltration membrane; it contains macromolecular impurities that are not completely retained by the ceramic membrane in the fermentation broth, such as proteins, reducing sugars, etc., and also includes some pigments and organic impurities with relatively large molecular weights. Among them, the reducing sugars include maltose, maltotriose, etc. that are not saccharified into glucose during the starch sugar production process. The presence of these impurities will affect the purity and quality of erythritol. If not effectively treated, it may have an adverse impact on subsequent processes such as crystallization, such as causing difficult crystallization and poor crystal quality. Some inorganic salts in the fermentation broth will also be enriched in the concentrated phase of the nanofiltration membrane. If these salts enter the subsequent erythritol products, they will affect the purity and taste of the products, and may also cause harm such as corrosion to the production equipment.

[0003] The concentrated phase of erythritol nanofiltration membranes is generally treated as waste sewage. Due to its high COD and conductivity, it often impacts the sewage treatment system and also causes waste of reducing sugars and erythritol.

[0004] Therefore, providing a method for reusing the concentrated phase of erythritol nanofiltration membranes is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a method for reusing the concentrated phase of erythritol nanofiltration membranes.

[0006] The content of soluble solids in the concentrated phase of erythritol nanofiltration membranes is 20.0% - 25.0%, the pH is 3.90 - 4.10, the light transmittance is basically zero, and the conductivity is 3.0 - 5.0 ms / cm; the reducing sugars account for 60.0% - 70.0% of the soluble solids, and erythritol accounts for 15.0% - 25.0% of the soluble solids. By adding activated carbon for filtration and decolorization, and using an ion exchange system for desalting, effective removal of other impurities except reducing sugars and erythritol in the concentrated phase of erythritol nanofiltration membranes can be achieved; adding a certain proportion of glucoamylase can convert the reducing sugars into glucose; adding the obtained glucose and erythritol mixture back into the erythritol fermentation medium can achieve the reuse of substances and is beneficial to cost savings.

[0007] To achieve the above object, the present invention adopts the following technical solutions: A method for recycling the concentrated phase of an erythritol nanofiltration membrane, comprising the following steps: (1) Plate-frame decolorization of the concentrated phase of the erythritol nanofiltration membrane: Detect the content of soluble solids in the concentrated phase of the erythritol nanofiltration membrane, add activated carbon in a certain proportion, and after heating, perform decolorization through a decolorization plate-frame; the addition ratio of the activated carbon is 1.5-2.0‰ of the content of soluble solids in the concentrated phase of the erythritol nanofiltration membrane; the heating temperature is 70-75°C, the plate-frame pressure is 0.3-0.4 Mpa, and the pore size of the filter cloth is 300-400 meshes.

[0008] (2) Ion exchange desalination: Pass the decolorized solution through an ion exchange system for desalination, detect and record the conductivity to determine the desalination effect; control the outlet conductivity ≤ 200 us / cm; the temperature of the decolorized solution passing through the ion exchange system is 50-55°C, the flow rate is 6.0-8.0 m 3 / h, and the resin types used are macroporous strong acid cation resin and macroporous strong base anion resin.

[0009] (3) Adjust the pH and add glucoamylase for reaction: Add the desalted solution to a saccharification tank, adjust the pH to 4.2-4.4, detect the content of reducing sugar, add glucoamylase in proportion, and perform a saccharification reaction; the addition amount of the glucoamylase is 0.30-0.35 kg / ton of reducing sugar; the enzyme activity of the glucoamylase is 150000 u / ml - 180000 u / ml; the saccharification conditions are a temperature of 59.0-62.0°C, a stirring rate of 25-30 rpm, and a saccharification time = 6-8 h.

[0010] (4) Detect the indexes and recycle for use: Detect the glucose content and erythritol content in the solution after the saccharification is completed, and recycle it to the erythritol fermentation broth for use according to the volume ratio of 1:2 of the erythritol fermentation broth to the treated concentrated phase of the nanofiltration membrane.

[0011] Further, the instrument for detecting the content of soluble solids in the concentrated phase of the erythritol nanofiltration membrane in step (1) is an Abbe refractometer.

[0012] Further, the content of soluble solids in the concentrated phase of the erythritol nanofiltration membrane in step (1) is 20.0%-25.0%, the pH is 3.90-4.10, the light transmittance is 0-5%, and the conductivity is 3.0-5.0 ms / cm; the content of reducing sugar in the soluble solids is 60.0%-70.0%, and the content of erythritol in the soluble solids is 15.0%-25.0%.

[0013] Further, the instrument for detecting the glucose content and erythritol content in the solution after the saccharification is completed in step (4) is a high performance liquid chromatograph, and the chromatographic column used is a hydrogen column.

[0014] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a method for reusing the concentrated phase of erythritol nanofiltration membrane, which has the following beneficial effects: (1) Currently, there are no relevant literatures and patents on the secondary utilization of the concentrated phase of erythritol nanofiltration membrane. The present invention has strong creativity and practicability in this field.

[0015] (2) The present invention improves the light transmittance of the concentrated phase of erythritol nanofiltration membrane to more than 50% by means of decolorization, ion exchange desalting, saccharifying enzyme saccharification, etc., removes more than 95% of inorganic salts, and retains more than 90% of erythritol; converts more than 95% of reducing sugars into glucose, increases the yield of erythritol by more than 80 g / L, and realizes the secondary utilization of waste and cost savings. Specific embodiments

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0017] Source of the concentrated phase of erythritol nanofiltration membrane: Refer to Patent 201710820906.1, a method for continuously extracting erythritol. Step (2) Nanofiltration: Filter the ultrafiltration permeate through a continuous nanofiltration membrane to obtain a nanofiltration concentrate (concentrated phase of erythritol nanofiltration membrane) and a nanofiltration permeate.

[0018] Example 1 A method for reusing the concentrated phase of erythritol nanofiltration membrane, comprising the following steps: (1) Plate-frame decolorization of the concentrated phase of erythritol nanofiltration membrane: Use an Abbe refractometer to detect that the content of soluble solids in the concentrated phase of erythritol nanofiltration membrane is 20.0%, the pH is 3.90, the light transmittance is 5%, and the conductivity is 3.0 ms / cm; detect that the content of reducing sugar is 60.0% of the content of soluble solids, and the content of erythritol is 15.0% of the content of soluble solids. Add activated carbon to the concentrated phase of erythritol nanofiltration membrane at a ratio of 1.5‰, heat up to 70 °C, and perform decolorization through a plate-frame with a filter cloth pore size of 300 meshes and a pressure of 0.3 Mpa. After decolorization, the detected light transmittance is 54.0%.

[0019] (2) Ion exchange desalting: Control the temperature of the decolorized solution to 50 °C and the flow rate to 6.0 m 3 / h, desalt through an ion exchange system, and detect that the conductivity of the discharged material is 122 μs / cm; the resin types used in the ion exchange system are macroporous strong acid cation resin and macroporous strong base anion resin.

[0020] (3) Adjust the pH and add glucoamylase for reaction: After desalination, the solution is added to the saccharification tank, the pH is adjusted to 4.2, the reducing sugar content is detected to be 12%, and glucoamylase is added for saccharification reaction according to the ratio of 0.30 kg glucoamylase per ton of reducing sugar; the enzyme activity of glucoamylase is 150,000 u / ml; the saccharification conditions are a temperature of 59.0 °C, a stirring rate of 25 rpm, and a saccharification time of 8 h.

[0021] (4) Detect the indicators and recycle: Use high-performance liquid chromatography to detect that the glucose content in the solution after saccharification is 11.6% (g / 100 g) and the erythritol content is 2.8%; recycle it to the erythritol fermentation broth for utilization (after erythritol fermentation using glucose as the substrate, add it to the fermentation broth according to the ratio of fermentation broth volume: volume of the concentrated phase of the treated nanofiltration membrane after concentration of 1:2, and continue fermentation until the erythritol content no longer increases). Compared with the control group (using glucose as the substrate for erythritol fermentation without recycling the concentrated phase of the nanofiltration membrane), the erythritol yield increases by 85 g / L.

[0022] The removal rate of inorganic salts = (3000 us / cm - 122 us / cm) / 3000 us / cm * 100% = 95.93%.

[0023] The retention rate of erythritol = 2.8% / (20% * 15%) * 100% = 93.33%.

[0024] The yield of converting reducing sugar to glucose = 11.6% / (20% * 60%) * 100% = 96.67%.

[0025] Example 2 A method for recycling the concentrated phase of erythritol nanofiltration membrane, comprising the following steps: (1) Plate-frame decolorization of the concentrated phase of erythritol nanofiltration membrane: Use an Abbe refractometer to detect that the soluble solid content in the concentrated phase of erythritol nanofiltration membrane is 23.0%, the pH is 4.00, the light transmittance is 3%, and the conductivity is 4.0 ms / cm; detect that the reducing sugar content is 65.0% of the soluble solid content and the erythritol content is 20.0% of the soluble solid content. Add activated carbon to the concentrated phase of erythritol nanofiltration membrane at a ratio of 1.8‰, heat up to 73 °C, and perform decolorization through a plate-frame with a filter cloth pore size of 350 mesh and a pressure of 0.35 Mpa. After decolorization, the light transmittance is detected to be 52.0%.

[0026] (2) Ion exchange for desalination: Control the temperature of the decolorized solution to 53 °C and the flow rate to 7.0 m 3 / h, desalt through the ion exchange system, and detect the conductivity of the discharged material to be 156 us / cm; the resin types used in the ion exchange system are macroporous strong acid cation resin and macroporous strong base anion resin.

[0027] (3) Adjust the pH and add glucoamylase for reaction: The solution after desalination is added to the saccharification tank, adjust the pH to 4.3, and the detected reducing sugar content is 14.9%. Add glucoamylase for saccharification reaction according to the ratio of 0.33 kg of glucoamylase per ton of reducing sugar; the enzyme activity of glucoamylase is 165000 u / ml; the saccharification conditions are: the temperature is 60.5 °C, the stirring rate is 28 rpm, and the saccharification time is 7 h.

[0028] (4) Detect the indicators and recycle: Use high-performance liquid chromatography to detect that the glucose content in the solution after saccharification is 14.3% and the erythritol content is 4.2%; recycle it to the erythritol fermentation broth for utilization (after erythritol fermentation with glucose as the substrate, add it to the fermentation broth according to the ratio of fermentation broth volume: volume of the concentrated phase of the treated nanofiltration membrane after concentration is 1:2, and continue to ferment until the erythritol content no longer increases). Compared with the control group (using glucose as the substrate for erythritol fermentation without recycling the concentrated phase of the nanofiltration membrane), the erythritol yield increases by 90 g / L.

[0029] The removal rate of inorganic salts = (4000 us / cm - 156 us / cm) / 4000 us / cm * 100% = 96.1%.

[0030] The retention rate of erythritol = 4.2% / (23% * 20%) * 100% = 91.3%.

[0031] The yield of converting reducing sugar to glucose = 14.3% / (23% * 65%) * 100% = 95.65%.

[0032] Example 3 A method for recycling the concentrated phase of an erythritol nanofiltration membrane, comprising the following steps: (1) Decolorize the concentrated phase of the erythritol nanofiltration membrane by plate and frame: Use an Abbe refractometer to detect that the soluble solid content in the concentrated phase of the erythritol nanofiltration membrane is 25.0%, the pH is 4.10, the light transmittance is 0%, and the conductivity is 5.0 ms / cm; detect that the reducing sugar content is 70.0% of the soluble solid content, and the erythritol content is 25.0% of the soluble solid content. Add activated carbon to the concentrated phase of the erythritol nanofiltration membrane at a ratio of 2.0‰, heat up to 75 °C, and perform decolorization through a plate and frame with a filter cloth aperture of 400 mesh and a pressure of 0.4 Mpa. After decolorization, the detected light transmittance is 51.5%.

[0033] (2) Desalt by ion exchange: Control the temperature of the decolorized solution at 55 °C and the flow rate at 8.0 m 3 / h, desalt through the ion exchange system, and detect that the conductivity of the discharged material is 212 us / cm; the resin types used in the ion exchange system are macroporous strong acid cation resin and macroporous strong base anion resin.

[0034] (3)Adjust the pH and add glucoamylase for reaction: After desalination, the solution is added to the saccharification tank, the pH is adjusted to 4.4, the reducing sugar content is detected to be 17.5%, and glucoamylase is added for saccharification reaction at a ratio of 0.35 kg of glucoamylase per ton of reducing sugar; the enzyme activity of the glucoamylase is 180,000 u / ml; the saccharification conditions are a temperature of 62.0 °C, a stirring rate of 30 rpm, and a saccharification time of 6 h.

[0035] (4)Detect the indicators and recycle for use: Use high performance liquid chromatography to detect that the glucose content in the solution after saccharification is 16.8% and the erythritol content is 5.8%; recycle it to the erythritol fermentation broth for use (after erythritol fermentation using glucose as the substrate, add it to the fermentation broth at a ratio of fermentation broth volume: volume of the concentrated phase after treatment by nanofiltration membrane of 1:2, and continue fermentation until the erythritol content no longer increases). Compared with the control group (using glucose as the substrate for erythritol fermentation without recycling the concentrated phase of the nanofiltration membrane), the erythritol production increases by 96 g / L.

[0036] The removal rate of inorganic salts = (5000 us / cm - 212 us / cm) / 5000 us / cm * 100% = 95.76%.

[0037] The retention rate of erythritol = 5.8% / (25% * 25%) * 100% = 92.8%.

[0038] The yield of reducing sugar converted to glucose = 16.8% / (25% * 70%) * 100% = 96.0%.

[0039] Control Example 1 (Directly recycle the concentrated phase to the fermentation broth for use) A method for recycling the concentrated phase of an erythritol nanofiltration membrane, comprising the following steps: (1)Detect the indicators of the concentrated phase of the erythritol nanofiltration membrane: Use an Abbe refractometer to detect that the soluble solid content in the concentrated phase of the erythritol nanofiltration membrane is 23.0%, the pH is 4.00, the light transmittance is 3%, and the conductivity is 4.0 ms / cm; detect that the reducing sugar content is 65.0% of the soluble solid content, and the erythritol content is 20.0% of the soluble solid content.

[0040] (2)Directly recycle the concentrated phase of the erythritol nanofiltration membrane to the erythritol fermentation broth (after erythritol fermentation using glucose as the substrate, add it to the fermentation broth at a ratio of fermentation broth volume: volume of the concentrated phase of the nanofiltration membrane of 1:2, and continue fermentation until the erythritol content no longer increases). Compared with the control group (using glucose as the substrate for erythritol fermentation without recycling the concentrated phase of the nanofiltration membrane), the erythritol production increases by 5 g / L.

[0041] The removal rate of inorganic salts is 0; the retention rate of erythritol is 100%; the yield of reducing sugar converted to glucose is 0.

[0042] Comparative Example 2 (without glucoamylase treatment) A method for reusing the concentrated phase of an erythritol nanofiltration membrane, comprising the following steps: (1) Plate-frame decolorization of the concentrated phase of the erythritol nanofiltration membrane: Using an Abbe refractometer, it was detected that the content of soluble solids in the concentrated phase of the erythritol nanofiltration membrane was 23.0%, the pH was 4.00, the light transmittance was 3%, and the conductivity was 4.0 ms / cm; the content of reducing sugar was 65.0% of the soluble solid content, and the content of erythritol was 20.0% of the soluble solid content. Activated carbon was added to the concentrated phase of the erythritol nanofiltration membrane at a ratio of 1.8‰, the temperature was raised to 73°C, and decolorization was carried out through a plate-frame with a filter cloth pore size of 350 meshes and a pressure of 0.35 Mpa. After decolorization, the light transmittance was detected to be 52.0%.

[0043] (2) Ion exchange for desalting: The temperature of the decolorized solution was controlled at 53°C, and the flow rate was 7.0 m 3 / h, and desalting was carried out through an ion exchange system. The conductivity of the discharged material was detected to be 156 μs / cm; the resin types used in the ion exchange system were macroporous strong acid cation resin and macroporous strong base anion resin.

[0044] (3) Detection of indicators and recycling for use: Using high-performance liquid chromatography, it was detected that the glucose content in the solution after the end of saccharification was 2.82% and the erythritol content was 4.2%; it was recycled into the erythritol fermentation broth for use (after fermentation with glucose as the substrate to produce erythritol, according to the ratio of the volume of the fermentation broth: the volume of the treated concentrated phase of the nanofiltration membrane was 1:2, and it was added to the fermentation broth and continued to ferment until the erythritol content no longer increased). Compared with the control group (using glucose as the substrate for erythritol fermentation without recycling the concentrated phase of the nanofiltration membrane), the erythritol yield increased by 15 g / L.

[0045] Inorganic salt removal rate = (4000 μs / cm - 156 μs / cm) / 4000 μs / cm * 100% = 96.1%.

[0046] Erythritol retention rate = 4.2% / (23% * 20%) * 100% = 91.3%.

[0047] Yield of reducing sugar converted to glucose = 2.82% / (23% * 65%) * 100% = 18.86%.

[0048] Comparative Example 3 (adjusting control indicators) A method for reusing the concentrated phase of an erythritol nanofiltration membrane, comprising the following steps: (1)Decolorization of the concentrated phase of erythritol nanofiltration membrane by plate and frame: Using an Abbe refractometer to detect that the content of soluble solids in the concentrated phase of erythritol nanofiltration membrane is 20.0%, pH is 3.90, light transmittance is 5%, and conductivity is 3.0 ms / cm; detecting that the content of reducing sugar is 60.0% of the soluble solids content, and the content of erythritol is 15.0% of the soluble solids content. Add activated carbon to the concentrated phase of erythritol nanofiltration membrane at a ratio of 1.4‰, heat up to 68 °C, and perform decolorization through a plate and frame with a filter cloth pore size of 250 mesh and a pressure of 0.25 Mpa. After decolorization, the detected light transmittance is 15.0%.

[0049] (2)Ion exchange desalination: Control the temperature of the decolorized solution at 48 °C and the flow rate at 5.0 m 3 / h, desalt through the ion exchange system, and detect that the conductivity of the discharged material is 556 μs / cm; the resin types used in the ion exchange system are macroporous strong acid cation resin and macroporous strong base anion resin.

[0050] (3)Adjust pH and add glucoamylase for reaction: Add the desalted solution to the saccharification tank, adjust the pH to 4.0, detect that the content of reducing sugar is 12%, and add glucoamylase for saccharification reaction at a ratio of 0.28 kg of glucoamylase per ton of reducing sugar; the enzyme activity of glucoamylase is 140,000 u / ml; the saccharification conditions are a temperature of 58.0 °C, a stirring rate of 20 rpm, and a saccharification time of 5 h.

[0051] (4)Detect indexes and recycle: Use high performance liquid chromatography to detect that the glucose content in the solution after saccharification is 6.8% (g / 100g) and the erythritol content is 2.1%; recycle it to the erythritol fermentation broth for utilization (after erythritol fermentation with glucose as the substrate, add it to the fermentation broth at a ratio of fermentation broth volume: volume of the treated concentrated phase of nanofiltration membrane of 1:2, and continue to ferment until the erythritol content no longer increases). Compared with the control group (using glucose as the substrate for erythritol fermentation without recycling the concentrated phase of nanofiltration membrane), the erythritol yield increases by 55 g / L.

[0052] Inorganic salt removal rate = (3000 μs / cm - 556 μs / cm) / 3000 μs / cm * 100% = 81.47%.

[0053] Erythritol retention rate = 2.1% / (20% * 15%) * 100% = 70.0%.

[0054] Yield of reducing sugar converted to glucose = 6.8% / (20% * 60%) * 100% = 56.67%.

[0055] Comparative Example 4 (Adjust control indexes) A method for recycling the concentrated phase of erythritol nanofiltration membrane, comprising the following steps: (1)Decolorization of the concentrated phase of erythritol nanofiltration membrane by plate and frame: Using an Abbe refractometer, it was detected that the content of soluble solids in the concentrated phase of erythritol nanofiltration membrane was 25.0%, the pH was 4.10, the light transmittance was 0%, and the conductivity was 5.0 ms / cm; the content of reducing sugar was detected to be 70.0% of the soluble solids content, and the erythritol content was 25.0% of the soluble solids content. Activated carbon was added to the concentrated phase of erythritol nanofiltration membrane at a ratio of 2.5‰, the temperature was raised to 78 °C, and decolorization was carried out through a plate and frame with a filter cloth aperture of 450 mesh and a pressure of 0.45 Mpa. After decolorization, the light transmittance was detected to be 56.5%.

[0056] (2)Ion exchange for desalting: The temperature of the decolorized solution was controlled at 57 °C, and the flow rate was 9.0 m 3 / h. Desalting was carried out through an ion exchange system, and the conductivity of the discharged material was detected to be 306 μs / cm; the resin types used in the ion exchange system were macroporous strong acid cation resin and macroporous strong base anion resin.

[0057] (3)Adjust the pH and add glucoamylase for reaction: The desalted solution was added to a saccharification tank, the pH was adjusted to 4.5, the content of reducing sugar was detected to be 17.5%, and glucoamylase was added at a ratio of 0.37 kg glucoamylase per ton of reducing sugar for saccharification reaction; the enzyme activity of glucoamylase was 190000 u / ml; the saccharification conditions were a temperature of 63.0 °C, a stirring rate of 35 rpm, and a saccharification time of 9 h.

[0058] (4)Detect the indicators and recycle for reuse: Using high-performance liquid chromatography, it was detected that the glucose content in the solution after saccharification was 12.3% and the erythritol content was 5.7%; it was recycled into the erythritol fermentation broth for reuse (after fermentation with glucose as the substrate, the fermentation broth was added to the treated concentrated phase of the nanofiltration membrane at a ratio of 1:2 of the fermentation broth volume to the volume of the concentrated phase of the treated nanofiltration membrane, and fermentation continued until the erythritol content no longer increased). Compared with the control group (fermenting erythritol with glucose as the substrate without recycling the concentrated phase of the nanofiltration membrane), the erythritol yield increased by 86 g / L.

[0059] Inorganic salt removal rate = (5000 μs / cm - 306 μs / cm) / 5000 μs / cm * 100% = 93.88%.

[0060] Erythritol retention rate = 5.7% / (25% * 25%) * 100% = 91.2%.

[0061] Yield of reducing sugar converted to glucose = 12.3% / (25% * 70%) * 100% = 70.29%.

[0062] It can be seen from Examples 1-3 and Comparative Examples 1-4 that: a method for reusing the concentrated phase of an erythritol nanofiltration membrane in Examples 1-3 can remove more than 95% of inorganic salts in the concentrated phase of the erythritol nanofiltration membrane and retain more than 90% of erythritol; more than 95% of reducing sugars are converted into glucose. Examples 1-3 increase the erythritol production by more than 80 g / L; although Comparative Example 4 also increases the erythritol production by more than 80 g / L, it takes a long time and has high costs, and is not suitable for actual production applications.

[0063] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can 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 these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for reusing the concentrated phase of an erythritol nanofiltration membrane, characterized in that, It includes the following steps: (1) Decolorization of the concentrated phase of erythritol nanofiltration membrane by plate and frame: Detect the content of soluble solids in the concentrated phase of erythritol nanofiltration membrane, add activated carbon in a certain proportion, and decolorize through a decolorizing plate and frame after heating; the addition ratio of the activated carbon is 1.5 - 2.0‰ of the content of soluble solids in the concentrated phase of erythritol nanofiltration membrane; the heating temperature is 70 - 75°C, the plate and frame pressure is 0.3 - 0.4 Mpa, and the pore size of the filter cloth is 300 - 400 meshes; (2) Ion exchange desalination: The decolorized solution is desalted through an ion exchange system, and the conductivity of the discharged material is controlled to be ≤200 μS / cm; the temperature of the decolorized solution passing through the ion exchange system is 50 - 55°C, and the flow rate is 6.0 - 8.0 m 3 / h, and the resin types used are macroporous strong acid cation resin and macroporous strong base anion resin; (3) Adjust pH and add glucoamylase for reaction: The desalted solution is added into a saccharification tank, adjust the pH to 4.2 - 4.4, detect the content of reducing sugar, add glucoamylase in proportion, and carry out saccharification reaction; the addition amount of the glucoamylase is 0.30 - 0.35 kg / ton of reducing sugar; the enzyme activity of the glucoamylase is 150000 u / ml - 180000 u / ml; the saccharification conditions are temperature 59.0 - 62.0°C, stirring rate 25 - 30 rpm, and saccharification time = 6 - 8 h; (4) Detect indexes and recycle for use: Detect the content of glucose and erythritol in the solution after saccharification is completed, and recycle it to the erythritol fermentation broth for use.

2. The reuse method of the erythritol nanofiltration membrane concentrated phase according to claim 1, characterized in that, The instrument for detecting the content of soluble solids in the concentrated phase of erythritol nanofiltration membrane in step (1) is an Abbe refractometer.

3. A method for reusing the concentrated phase of erythritol nanofiltration membrane according to claim 1, characterized in that, The content of soluble solids in the concentrated phase of erythritol nanofiltration membrane in step (1) is 20.0% - 25.0%, pH is 3.90 - 4.10, light transmittance is 0 - 5%, and conductivity is 3.0 - 5.0 ms / cm; the content of reducing sugar in soluble solids is 60.0% - 70.0%, and the content of erythritol in soluble solids is 15.0% - 25.0%.

4. A method for reusing the concentrated phase of an erythritol nanofiltration membrane according to claim 1, wherein, The instrument for detecting the content of glucose and erythritol in the solution after saccharification is completed in step (4) is a high performance liquid chromatography, and the chromatographic column used is a hydrogen column.